Low-cost delafossite-perovskite nanocomposite for improved energy storage applications
Sivaguru G., Ghorui U.K., Sangaraju S., Chakrabortty S.
Article, Materials Chemistry and Physics, 2026, DOI Link
View abstract ⏷
Designing of efficient electrode material for the enhancement of energy density with extended cycle life for supercapacitors is a crucial factor. Transition metal oxides (TMOs) and Mixed TMOs are such nanomaterials which has been explored extensively due to its cost-effective and earthly abundance. But the low specific capacitance with electrochemical and structural instabilities obstructs TMOs from its practical application. To address this challenge, a low-cost nanocomposite with a delafossite-type (CuCrO2(CCO)) and perovskite-type (CuZrO3(CZO)) crystal structure has been developed which displayed an enhanced electrochemical activity and prolonged cycle life for charge storage applications. This nanocomposite demonstrated remarkable charge storage capability, delivering maximum capacity value of 179.5 C/g (373.12 F/g) in 2 M potassium hydroxide (KOH) at 0.5 A/g, and sustaining cycle life of 5000 GCD runs at 5 A/g. Furthermore, we constructed a hybrid supercapacitor (HSC) device that revealed high power and energy density of 600 W/kg and 24 Wh/kg at 1 A/g, and preserved 80 % of its capacitance with a minimal loss in coulombic efficiency. Additionally, to ascertaining the potential sustainability in energy storage applications, we have integrated them with a commercially available photovoltaic (PV) module and demonstrated the device's capability to power a standard light emitting diode (LED).
Investigation on plastic-aggregates in coastal and marine pollution: Distribution, possible formation process, and disintegration prospects
Review, Physics and Chemistry of the Earth, 2025, DOI Link
View abstract ⏷
Plastic-aggregates are made up from unused or waste plastic and natural aggregates which have recently been emerged as a significant addition to the existing emerging contaminants list mainly in the coastal environment. The transformation from plastics/microplastics to Plastic-aggregates signifies a crucial shift in our understanding and use of plastics and prompting us to reconsider their fundamental characteristics along with possible environmental threats. When plastic waste is incinerated for the purpose of disposal, it combines with organic and inorganic substances present in the surrounding environment, leading to a new type of material. Besides, some natural factors (physical, chemical, biological or in combination) also act upon discarded plastics to combine with rocks and other earthen materials to form plastic-aggregates. Our research aims to build fundamental knowledge and critically review the possible formation process, classification, and possible degradation of all such polymer-rock compounds along with their impact on the ecosystem. The knowledge gap related to the degradation and release of secondary pollutants from these agglomerates is to be addressed urgently in future research. Development and standardization of proper sampling and reporting procedures for plastic-aggregates can enhance our understanding related to their impacts on human health as well as to the entire environment as these aggregates contain different toxic chemicals.
Defect-Engineered N-Doped Graphene Oxide-ZnWO4 Nanocuboids: Advancing Oxygen Reduction and Photo-Assisted Methanol Oxidation Reactions
Ghorui U.K., Sivaguru G., Sk M., Thapa R., Sampath M.V.R.A., Chakrabortty S.
Article, Small, 2025, DOI Link
View abstract ⏷
The development of direct methanol fuel cells (DMFCs) relies on designing replacements for benchmark platinum (Pt)-based electrocatalysts toward methanol oxidation reaction (MOR) that exhibit high resistance to CO poisoning, improve kinetic sluggishness, devoid of unwanted intermediates, low catalyst cost, and wide operating conditions. This study presents the development of defect engineering N-doped graphene oxide (NG) supported ZnWO4 nanocuboids as an efficient catalyst for photoelectrochemical MOR and electrochemical ORR. Under visible light (420 nm), the NG/ZnWO4 nanohybrid exhibits exceptional photoelectrochemical MOR with low potential of 0.5V with a high oxidation peak current density of ≈10 mA cm−2 is recorded while comparing with benchmark catalyst Pt/C. In two electrode systems for DMFC, the catalyst reaches an impressive maximum power production of 111 mW cm−2 with very stable charge-discharge cycles of 0.33 mV cycle−1, which is far superior to ZnWO4’s alone. Simultaneously, the nanocomposite exhibits excellent ORR activity in alkaline medium with improved onset half-wave potential of 0.85V, high current density of 5.8 mA cm−2 at 1600 rpm, and robust stability, attributed to the synergistic effect between NG and ZnWO4. This work has reinforced these findings with theoretical insights using the Vienna Ab initio Simulation Package (VASP) to assess both PMOR and ORR performance and reaction intermediates.
Hybrid Inorganic-Biomolecular Materials for Bioelectronics Applications
Article, Journal of Electronic Materials, 2025, DOI Link
View abstract ⏷
The hybridization of biomolecules with gold nanoclusters (AuNCs) has emerged as a promising research direction in bioelectronics, extending multidimensional prospects for diverse applications, from wearable health monitoring to advanced medical devices and tissue engineering. Here, we report a hybrid of bovine serum albumin (BSA) protein and gold nanoclusters of various concentrations to harness the distinctive properties of gold nanoclusters and enhance the electronic functionalities of biomolecules. Self-assembled monolayers (SAMs) of hybrid materials demonstrate enhanced electrical conduction with a film thickness of 10–15 nm as obtained from atomic force microscopy topographical images, revealing minimal aggregation. Current–voltage (I–V) characteristics at ±0.5 V showed significantly higher current densities for optimized hybrid material (BSA-Au6) SAMs, reaching 150 A/cm2. Compared to prior studies on BSA and metal hybrid thin films, the observed 100-fold enhancement in electrical conductivity for AuNC-doped SAMs highlights the novelty of this work. Moreover, our study with different AuNC concentrations demonstrated that six equivalents of AuNCs significantly boosted conductivity due to efficient electron transport mechanisms, which was further investigated with electrical impedance measurements. Our findings provide valuable insights into the underlying electronic transport mechanisms across hybrid materials for applications in bioelectronics and molecular electronics, marking a breakthrough compared to conventional protein films.
Impact of Organic Precursors on the Optoelectronic Properties of As-Synthesized Carbon Dots
Article, ChemNanoMat, 2025, DOI Link
View abstract ⏷
Carbon dots (CDs), versatile carbon-based luminescent nanomaterials, offer environmental friendliness, cost-effectiveness, and tunable optical properties for diverse optoelectronic applications, including light-emitting diodes, photodetectors, and flexible electronics. These nanoscale materials exhibit unique optical behaviors like highly tunable photoluminescence and efficient multiphoton up-conversion. Herein, it explores how precursor selection influences CDs’ sp2/sp3 hybridization ratios and their optoelectronic properties. CDs are synthesized from four distinct sources: polymeric polyvinylpyrrolidone, protein, biomass, and citric acid. Biomass- and protein-derived CDs display remarkable photocurrent enhancements under blue light, attributed to balanced sp2/sp3 ratios, while polymer-derived CDs show limited optoelectronic response. These findings reveal the critical role of precursor composition in tailoring the structural and electronic properties of CDs, offering sustainable pathways for their application in advanced optoelectronic devices.
Facile Fabrication of Multifunctional Superhydrophobic Surfaces Synthesized by the Additive Manufacturing Technique Modified with ZnO Nanoparticles
Article, Langmuir, 2025, DOI Link
View abstract ⏷
This article reports facile fabrication of a multifunctional smart surface having superhydrophobic self-cleaning property, superoleophilicity, and antimicrobial property. These smart surfaces have been synthesized using the stereolithography (SLA) method of the additive manufacturing technique. SLA is a fast additive manufacturing technique used to create complex parts with intricate geometries. A wide variety of materials and high-resolution techniques can be utilized to create functional parts such as superhydrophobic surfaces. Various materials have been studied to improve the functionality of 3D printing. However, the fabrication of such materials is not easy, as it is quite expensive. In this work, we used a commercially available SLA printer and its photopolymer resin to create various micropatterned surfaces. Additionally, we applied a low surface energy coating with ZnO nanoparticles and tetraethyl orthosilicate to create hierarchical roughness. The wettability studies of created superhydrophobic surfaces were evaluated by means of static contact angle using the sessile drop method and rolling angle measurements. The effects of various factors, including different concentrations of coating mixture, drying temperatures, patterns (pyramids, pillars, and eggbeater structures), and pillar spacing, were studied in relation to contact angles. Subsequently, all the functional properties (i.e., self-cleaning, oleophilicity, and antibacterial properties) of the as-obtained surfaces were demonstrated using data, images, and supporting videos. This inexpensive and scalable process can be easily replicated with an SLA 3D printer and photopolymer resin for many applications such as self-cleaning, oil-water separation, channel-less microfluidics, antibacterial coating, etc.
A comprehensive review on realization of self-cleaning surfaces by additive manufacturing
Review, Progress in Additive Manufacturing, 2025, DOI Link
View abstract ⏷
Self-cleaning surfaces revolutionizing the technology world due to their novel property of cleaning themselves, and its multi-functional self-cleaning surfaces exhibit at least one or more functional properties (transparent, conducting, anti-bacterial, anti-corrosion, etc.) This review article focuses on the fundamentals of wettability, material parameters controlling surface wettability and three different paths to realization of self-cleaning surfaces, i.e., (i) super-hydrophobic, (ii) super-hydrophilic and (iii) photocatalytic. The subsequent part of the article mostly focuses on the super-hydrophobic path towards realizing self-cleaning surfaces. In the super-hydrophobic path, the objective is to make the surface extremely repellent to water so that water droplets slide and ‘roll off’ from the surface. The next section of the review article focuses on the role of additive manufacturing in the fabrication of super-hydrophobic micro-structures. Amidst the different fabrication processes of self-cleaning surfaces, additive manufacturing stays ahead as it has the manufacturing capacity to create complex micro-structures in a scalable and cost-effective manner. A few prominent types of additive manufacturing processes were strategically chosen which are based on powder bed fusion, vat photopolymerization, material extrusion and material jetting techniques. All these additive manufacturing techniques have been extensively reviewed, and the relative advantages and challenges faced by each during the scalable and affordable fabrication of super-hydrophobic self-cleaning surfaces have been discussed. The article concludes with the latest developments in this field of research and future potential. These surfaces are key to answer sustainable development goals in manufacturing industries.
Effect of surface ligands on the photocatalytic hydrogen production of Cu nanoclusters
Article, International Journal of Hydrogen Energy, 2025, DOI Link
View abstract ⏷
In this study, tiny sized (∼2 nm) copper nanoclusters (Cu NCs) were synthesized with strong optical response, where red/green emitting features were observed using protein/amino acid as surfactant molecules. The photocatalytic water splitting reactions for both ligand-mediated Cu NCs were carried out in a photochemical reactor under solar simulator for 12 h. Interestingly, protein mediated red colour emitting Cu NCs produced stable H2 ∼ 256 mmol g−1 and the solar to hydrogen efficiency (STH) is approximately ∼ 0.5% while comparing with green emitting Cu NCs with 86 mmol g−1 and STH of 0.08%. These interesting results were achieved due to their longer lifetime, strong colloidal stability, high quantum yield and rich surface functionalization features. These were further confirmed through absorption spectroscopy, fluorescence spectroscopy, time-resolved photoluminescence, zeta potential, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy analytical techniques. Thus, these inexpensive Cu NCs could be used as alternate photocatalysts for H2 production than obviating the usage of precious noble metal platinum-based ones.
A comprehensive biocompatibility evaluation of fluorescent gold nanoclusters using Caenorhabditis elegans as a model organism
Article, Materials Today Chemistry, 2025, DOI Link
View abstract ⏷
Gold nanoclusters (Au NCs) have found wide range of applications in environmental, chemical and health sectors as sensors, catalytic agents and theranostic molecules, respectively, due to their ultrasmall size and excellent optical properties. However, a comprehensive battery of bioassays of Au NCs were lacking on a well-established biological model system, which would enhance its potential to be used as an optical probe with application in theranostics. The current investigation aims to address the in vivo compatibility of Au NCs to improve their design, evaluate their biological impact, and validate their potential for bioimaging applications. We have used the Caenorhabditis elegans as a model organism in our present study due to their short life cycle facilitating evaluation of drug effects in reasonable time frame and transparent body framework suitable for in vivo imaging. These features facilitate accurate information regarding the uptake and biodistribution of Au NCs inside the tissues and body parts. Additionally, different nanotoxicological studies such as biodistribution of NCs and its subsequent impact on the health span, brood size, pharyngeal pumping and tail thrashing of C. elegans were observed as a measure of the Au NCs biocompatibility. Our results strongly demonstrate that the human serum albumin (HSA)-bound Au NCs are non-toxic, biocompatible and do not exhibit any adverse effect on the physiology and survival of the C. elegans. This study, employing a comprehensive battery of bioassays, is the first to systematically evaluate the long-term biocompatibility and non-toxicity of Au NCs across the entire lifespan of an organism, measured through multiple physiological parameters. These findings underscore the potential of Au NCs as safe and effective diagnostic and therapeutic agents for medical and clinical applications.
Tuning the Hydrophobicity of Laser-Annealed rGO Thin Films Synthesized by Pulsed Laser Deposition
Sherin P A T., Raman T. S A., Juvaid M.M., Rana A., Sangaraju S., Chakrabortty S., Rana A., Raju K.C.J., Ghosh S.
Article, Langmuir, 2025, DOI Link
View abstract ⏷
Reduced graphene oxide (rGO) has captivated the scientific community due to its exceptional electrical conductivity, high specific surface area, and excellent mechanical strength. The physical properties of reduced graphene oxide (rGO) are strongly dependent on the presence of different functional groups in its structural framework, along with surface roughness. In this study, laser annealing was employed by a nanosecond Nd:YAG laser to investigate the impact of varying laser energies on the wettability and conductivity of reduced graphene oxide (rGO) samples grown by the pulsed laser deposition (PLD) technique. The rGO films were annealed with different laser fluences, such as 10, 20, 30, 38, 48, 55, and 250 mJ/cm2. Our results reveal a notable transition in wettability, transforming the initially hydrophobic rGO samples into a hydrophilic state. Hydrophilic graphene oxide (GO) or reduced graphene oxide (rGO) surfaces have significant potential for use in biomedical applications due to their unique combination of properties, including biocompatibility, high surface area, and abundant oxygen-containing functional groups. Along with wettability properties, conductivity changes were also observed. The presented findings not only contribute to the understanding of laser-induced modifications in rGO but also highlight the potential applications of controlled laser annealing in tailoring the surface properties of graphene-based materials for diverse technological advancements.
α-Fe2O3 Nanostructures: Bridging Morphology with Magnetic and Antimicrobial Properties
Krishna A.M.S., George N., Lavanya V., Kumar D., Chaurasiya A., Rahaman H., Piramanayagam S.N., Rawat R.S., Dalapati G.K., Ball W.B., Ghosh S., Chakrabortty S.
Article, ChemNanoMat, 2025, DOI Link
View abstract ⏷
Highly crystalline hematite (α-Fe2O3) nanostructures (NSs) with distinct morphology hold vital significance, not only for fundamental knowledge of magnetic properties but also offering potential applications from biomedical to data storage to semiconductor industry, etc. α-Fe2O3 NSs with various shapes are examined to reveal the intrinsic relationship between the shape anisotropy and magnetic properties. Herein, different morphologies of α-Fe2O3 NSs, such as spherical, cubic, plate-like, rhombohedral, and hexagonal bipyramid are synthesized, by controlled hydrothermal method. The impact of shape and size on the optical and structural characteristics through UV–vis absorption spectroscopy and X-ray diffraction is analyzed. Advanced nanomaterial techniques such as transmission electron microscopy are utilized to explore and confirm the morphology and size of NSs. Subsequently magnetic properties of the α-Fe2O3 NSs, such as magnetic saturation (Ms), coercivity (Hc), and remanent magnetization (Mr), are measured. Careful analysis of magnetic data reveals Morin transition around 200 K for cubic, plate-like, and rhombohedral samples, whereas the spherical and hexagonal bipyramid samples illustrate the superparamagnetic behavior in the temperature range of 150–300 K. Finally, the antibacterial characteristics of NSs against Escherichia coli using a microplate reader for monitoring the bacterial growth are investigated.
Corrigendum to “A comprehensive biocompatibility evaluation of fluorescent gold nanoclusters using Caenorhabditis elegans as a model organism” [Volume 45 (2025) 102642] (Materials Today Chemistry (2025) 45, (S2468519425001326), (10.1016/j.mtchem.2025.102642))
Erratum, Materials Today Chemistry, 2025, DOI Link
View abstract ⏷
The authors regret the oversight in one of the author's (Manjunatha Thondamal) affiliation details occurred during the final proof reading. The affiliation detail for the author-Manjunatha Thondamal is: d Department of Biotechnology, School of Technology, Gandhi Institute of Technology and Management (GITAM), Visakhapatnam, Andhra Pradesh, 530045, India. The authors would like to apologise for any inconvenience caused.
Substrate and Step Rate Dependence Electrodeposition of Nickel–Cobalt–Molybdenum–Phosphorous Alloy for Efficient Hydrogen Evolution Reaction
Samanta A., Mohapatra L., Ghorui U.K., Rathour A., Kushwaha A.K., Ghosh S., Tripathy S., Guo W., Reddy V.S., Biring S., Chakrabortty S., Dalapati G.K.
Article, Energy Technology, 2025, DOI Link
View abstract ⏷
Understanding the hydrogen economy involves recognizing the crucial role of water-splitting in producing green, clean, and carbon-free hydrogen. In that respect, the role of catalyst is very important as it enhances the reaction rate and efficiency, making hydrogen production more viable and sustainable. Herein, nickel–cobalt–molybdenum–phosphorous (Ni–Co–Mo–P) alloy has shown efficient catalysis properties for hydrogen evolution reaction (HER) in an alkaline medium. The quaternary alloys are directly grown on different substrates like nickel sheet, copper sheet, and stainless-steel sheet by employing a simple pulse electrodeposition method. The method is conducted with a pulse interval time of 15 s at various pulse rates while maintaining the pH of 4 at room temperature. The alloy deposition is performed at a potential range from −1.5 V to −0.15 V (vs Ag/AgCl). The electrodeposition of the alloy in different substrates is first established with X-Ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Raman spectroscopy. The deposited quaternary alloy exhibits the lowest overpotential of −163 mV at 10 mA cm−2 for copper substrate with a Tafel slope of 154 mV dec−1. The microcrystalline structure or amorphous nature and the rough grain surface of Ni-Co-Mo-P alloys have characterized by XRD and scanning electron microscopy micrograph, respectively.
Exploring the Potential and Roadblocks of Marketable Energy-Storage Technologies for Renewable Energy
Srivastava M., Ramasubramanian B., Ghorui U.K., Dalapati G.K., Selvaraj V., Kumar A., Biring S., Ribeiro C.S., Ghosh S., Krishnamurthy S., Chakrabortty S.
Review, Energy Technology, 2025, DOI Link
View abstract ⏷
Renewable energy has gained widespread recognition for its potential to drive sustainable power generation and mitigate climate change. However, the rapid expansion of these resources highlights inherent challenges arising from their non-dispatchable, intermittent, and asynchronous nature, underscoring the critical need for grid-scale energy storage. Although numerous storage technologies exist, cohesive insights into commercially available or nearing commercialization remain limited. The review addresses that gap by presenting a comprehensive analysis of marketable grid-scale energy-storage solutions. The discussion begins with an examination of growth dynamics and regional trends in energy-storage capacities worldwide. By using California and Saudi Arabia as representative samples of the Mediterranean and hot desert regions under the Köppen classification, the review illustrates how climatic zones influence energy-storage requirements. After highlighting recyclability challenges associated with lithium-ion batteries, the study explores emerging electrochemical and gravitational-storage technologies. It then articulates critical parameters for evaluating energy-storage solutions and provides a comparative performance analysis. The review concludes by identifying a range of commercialized innovations and recommending a holistic approach to strengthen reliance on renewable energy.
Nonlinear and linear conductance modulation and synaptic plasticity in stable tin-zinc oxide based-memristor for neuro-inspired computing
Rajwali Khan, Shahid Iqbal, Fazal Raziq, Maram P.S., Chakrabortty S., Sangaraju S.
Article, Materials Science in Semiconductor Processing, 2025, DOI Link
View abstract ⏷
Inducing post-transition metals in an oxide semiconductor system has a high potential for use in storage for neuromorphic computing. It is challenging to find a material that can be switched stably between multiple resistance states. This research explores the memristive properties of Sn (post-transition metal)-doped ZnO (SZO) thin films, emphasizing their application in memristor devices. The (magnetron sputtered) synthesized SZO thin films in the form of Ag/SZO/Au/Ti/SiO₂ device demonstrated a clear bipolar resistive switching (BRS) behavior with VSET and VRESET of 1.0 V and −0.75 V, respectively. The memristor could change between a high resistance state and a low resistance state with a high RON/OFF rate of 104, mimicking synaptic behaviors such as potentiation and depression. This switching is attributed to the formation and dissolution of Ag filaments within the SZO layer, influenced by the migration of Ag⁺ ions and the presence of oxygen vacancies. These vacancies facilitate the formation of conductive filaments under positive bias and their dissolution under negative bias. The endurance and retention tests showed stable switching characteristics, with the memristor maintaining distinct HRS and LRS over 100 cycles and retaining these states for over 5K seconds without significant degradation. Finally, the nonlinearity values for potentiation and depression were αp∼1.6 and αd ∼ -0.14, suggesting that the memristor may be more responsive to increasing synaptic weights in biological systems. The linearity response at a very small pulse width showed the device is more applicable for neuromorphic applications. The observed memristor combined with stable endurance and retention performance, suggests that this memristor structure could play a crucial role in the development of artificial synapses and memory technologies.
Photoredox/Nickel Dual Catalysis for Regio- and Stereoselective Reductive Coupling of Alkynes with Vinyl Phosphonates
Sakthiganapathi R., Sharma D.K., Dutta R., Chakrabortty S., Baskar B., Mannathan S.
Article, Journal of Organic Chemistry, 2025, DOI Link
View abstract ⏷
An efficient nickel-photoredox dual-catalyzed intermolecular reductive coupling reaction of alkynes with vinyl phosphonates is described. The reaction is highly regio- and stereoselective, affording the homoallylic phosphonates in good to high yields. The present protocol is also successfully applied to other activated alkenes such as enones, acrylates, and vinyl sulfone. The reaction is believed to proceed via the nickelacyclopentene intermediate. Mechanistic investigations, including control experiments and isotopic labeling studies, revealed that methanol serves as a proton source rather than a reducing agent.
Enhanced electrochemical performance of (MoSe2@NiSe2) (0D/1D) hybrid nanostructures for supercapacitors
Dhanasekaran G., Parthiban N., Keerthana T., Gopal R., Sambasivam Sangaraju, Chakrabortty S., Thangavel E.
Article, Materials Science and Engineering: B, 2025, DOI Link
View abstract ⏷
Improving and reducing the cost of electrochemical performance is critical to developing energy storage technology. In this study, we investigated the effects of incorporating NiSe2 into the MoSe2, then the electrochemical behaviour of MoSe2@NiSe2 (0D/1D) hybrid-nanostructure prepared using a hydrothermal method. The Scanning electron microscopy (SEM) images confirmed that MoSe2, MoSe2@NiSe2 (0D/1D) hybrid-nanostructure in composites with surface enhancement. The MoSe2@NiSe2 (0D/1D) hybrid-nanostructure exhibits enhanced specific capacitance of 802 F g−1 compared to MoSe2 and shows extended cycle life up to 5000 cycles with 92.7 % of capacity retention. In addition, the active electrode consisting of MoSe2@NiSe2 (0D/1D) hybrid-nanostructure exhibits high ionic affinity due to the presence of abundant electrochemically active sites, which can reduce the internal resistance and lead to accelerated ion transport. Our results demonstrate that a simple and scalable approach can significantly improve the electrochemical performance of the MoSe2@NiSe2 (0D/1D) hybrid nanostructure.
B-doped GQD supported cobalt sulfide nanocomposite: A defect engineering approach for superior oxygen electrode performance
Ghorui U.K., Sampath M.R.A., Sivaguru G., Dutta R., Sangaraju S., Chakrabortty S.
Article, Catalysis Today, 2025, DOI Link
View abstract ⏷
Developing an efficient and durable electrocatalysts for oxygen electrolysis is crucial for advancing clean energy technologies. However, the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), along with catalyst degradation, remain major obstacles. Here, we optimized the composition of composite nanocatalysts obtained by doping of an electron deficient, B-atoms into graphene quantum dots (GQD) attached with Cobalt Sulfide (CoS) nanostructures. Optimizing the surface structure and investigating the interfacial interactions, the catalyst demonstrated an exceptional oxygen electrode reaction performance. The faster electronic synergism between the defect engineering BGQD and CoS offers more catalytic active sites as well as faster electrical conductivity and higher adsorption/desorption rate of oxygenated intermediates at the electrode surface for the electrolysis processes. Among the optimized composite electrode material CSBGQD-13 (CoS/BGQD (1:3)) exhibited high positive onset (Eonset = 1.04 V vs. RHE) and half-wave potential (E1/2 = 0.84 V vs. RHE) with high limiting current density of 7.6 mA/cm2 at 1600 rpm and a reasonable resistance to the MeOH crossover effect during ORR. In addition, our electrocatalyst demonstrated long-term durability and effective OER activity with the lowest Tafel slope of 82 mV/dec among other CSBGQDs and a lower overpotential of 0.27 V vs. RHE at a current density of 10 mA/cm2. Furthermore, the CSBGQD-13 claims excellent dual function electrocatalytic performance towards ORR and OER with a very small ΔE value (only 0.66 V vs. RHE), a higher catalytic current density. Henceforth, for possible fuel cell applications, we believe that this electrode material may provide an understanding of the principles of metal sulfide carbon dots hybrid catalysts.
Advanced Materials for Sustainable Energy and Decarbonization
Biswas B., Wong T.K.S., Dalapati G.K., Chakrabortty S.
Editorial, ACS Applied Energy Materials, 2025, DOI Link
Phase transition and bandgap modulation in TiO2 nanostructures for enhanced visible-light activity and environmental applications
Khan R., Rahman N., Prasannan A., Ganiyeva K., Chakrabortty S., Sangaraju S.
Article, Scientific Reports, 2025, DOI Link
View abstract ⏷
Due to its wide-ranging applications in the climate and energy fields, enhancing the visible-light photoactivity of TiO2 nanoparticles remains a crucial challenge in photocatalysis. Interestingly, this work examined the phase transition, structural, optical, and photocatalytic characteristics of TiO2 nanoparticles doped with Al3⁺/Al2⁺ and S⁶⁺ ions. It was observed that the anatase phase (AP) dominates in pure TiO2 (100%) nanoparticles, whereas the rutile phase (RP) content increases in doped samples, reaching 20 ± 2.1% for X1 (Al = 2%, S = 2%) and falling to 12 ± 1.2% in X4 (Al = 2%, S = 8%). The introduction of Al3⁺/Al2⁺ and S⁶⁺ induces oxygen vacancies (Ovs) and alters the phase stability, as evidenced by the reduction of transformation energy to − 0.033 eV, facilitating the AP to RP transition. The effective integration of dopants indicates that a redshift and intensity in the Photoluminescence spectrum reduced by X-series nanoparticles is due to band gap reductions (from 3.23 eV for pure TiO2 to 1.98 eV for X4) and distortions in the lattice generated by Al/S doping. Raman spectroscopy results show peak broadening and shifts due to lattice strain from dopants, which validates dopant incorporation via peak shifts in Fourier-transform infrared spectroscopy. ESR study reveals paramagnetic centers in Ti3⁺-Ovs complexes, indicating defect-induced magnetic characteristics. When methylene blue (MB) dye is photocatalyzed under visible light exhibits increased activity and degradation efficiencies that are higher than pure TiO2. The pseudo-first-order kinetic results show that co-doping effectively improves photocatalytic activity. Rate constants of 0.017 min⁻1 for X4 are found to be much higher than 7.28 × 10⁻4 min⁻1 for pure TiO2 nanoparticles. Finally, anatase X-series samples degraded MB at a maximum rate of 96.4% in 150 min, outperforming undoped TiO2 (15%) and rutile-TiO2 nanoparticles (65% degradation). The fundamental mechanism explains that the photocatalytic characteristics of TiO2 are modulated by co-doping, which is why these compounds are potential candidates for environmental remediation applications.
Potential applications for photoacoustic imaging using functional nanoparticles: A comprehensive overview
Neelamraju P.M., Gundepudi K., Sanki P.K., Busi K.B., Mistri T.K., Sangaraju S., Dalapati G.K., Ghosh K.K., Ghosh S., Ball W.B., Chakrabortty S.
Review, Heliyon, 2024, DOI Link
View abstract ⏷
This paper presents a comprehensive overview of the potential applications for Photo-Acoustic (PA) imaging employing functional nanoparticles. The exploration begins with an introduction to nanotechnology and nanomaterials, highlighting the advancements in these fields and their crucial role in shaping the future. A detailed discussion of the various types of nanomaterials and their functional properties sets the stage for a thorough examination of the fundamentals of the PA effect. This includes a thorough chronological review of advancements, experimental methodologies, and the intricacies of the source and detection of PA signals. The utilization of amplitude and frequency modulation, design of PA cells, pressure sensor-based signal detection, and quantification methods are explored in-depth, along with additional mechanisms induced by PA signals. The paper then delves into the versatile applications of photoacoustic imaging facilitated by functional nanomaterials. It investigates the influence of nanomaterial shape, size variation, and the role of composition, alloys, and hybrid materials in harnessing the potential of PA imaging. The paper culminates with an insightful discussion on the future scope of this field, focusing specifically on the potential applications of photoacoustic (PA) effect in the domain of biomedical imaging and nanomedicine. Finally, by providing the comprehensive overview, the current work provides a valuable resource underscoring the transformative potential of PA imaging technique in biomedical research and clinical practice.
Emerging trends in cooling technologies for photovoltaic systems
Mariam E., Ramasubramanian B., Sumedha Reddy V., Dalapati G.K., Ghosh S., PA T.S., Chakrabortty S., Motapothula M.R., Kumar A., Ramakrishna S., Krishnamurthy S.
Review, Renewable and Sustainable Energy Reviews, 2024, DOI Link
View abstract ⏷
Photovoltaic systems (PV), particularly solar photovoltaics, are gaining popularity as renewable energy sources. The rapid deployment of PV systems has attracted substantial investments, with around $170 billion projected by 2025. However, challenges like dust accumulation, solar radiation, and temperature rise hinder PV efficiency. Elevated temperatures, exceeding standard levels, notably decrease voltage output and overall electricity generation efficiency. This review provides a comprehensive overview of recent cooling techniques adopted to enhance solar PV performance. Beginning with an introduction to global warming's impact and renewable energy's significance, the article explores cooling methodologies for solar PVs. These encompass Absorption & adsorption-based, PV/T hybrid, Microtechnology-based, and Water and air-based cooling systems. The review concludes this section with a detailed table comparing cooling technologies' performance, benefits, and challenges. The review then delves into four primary cooling techniques: Active cooling, Passive cooling, Nanofluid-based cooling, and Thermoelectric cooling. Passive cooling, which effectively reduces PV system temperature without external energy sources, is highlighted. Modalities of Passive cooling methods, such as Radiative cooling, Evaporative cooling, Liquid immersions, and Material coatings, are elaborated. Concluding, the article addresses challenges, opportunities, and future prospects related to diverse cooling techniques' utilisation, aiming to elevate solar PV system efficiency.
Rational design of Mg(OH)2/Cu2(OH)3(NO3) binary heterostructure electrodes for enriched supercapacitors performance
Karthigaimuthu D., Raju K., Chakrabortty S., Ghosh S., Arjunkumar B., Elangovan T., Sambasivam S.
Article, Ionics, 2024, DOI Link
View abstract ⏷
The electrode material properties, such as widening the voltage window, rational design, and morphology are known to play an essential role in increasing its efficiency for energy storage devices. Herein, a simple strategy to first prepare a Mg(OH)2/Cu2(OH)3(NO3) (MHCNx) binary heterostructure by co-precipitation method. The morphology studies from SEM and HR-TEM analysis revealed that the Mg(OH)2 and Mg(OH)2/Cu2(OH)3(NO3) binary heterostructures show quasi-spherical and nanosheet-like structures. The electrochemical characteristics of as-prepared binary heterostructure electrodes were investigated by a three-electrode system. At a low current density of 5 Ag−1, the specific capacitance of the MHCN-2 achieved 146 Fg−1. The MHCN-2 electrode displayed capacitance retention of ~ 97% and coulombic efficiency of ~ 96% for 5000 cycles. This study offers a facile and low cost approach for producing novel nanostructures and electrodes for energy storage in binary heterostructure materials. Graphical Abstract: [Figure not available: see fulltext.].
Sputter grown CuO thin films: Impact of growth pressure and annealing temperature on their microstructural architectures
Sai Krishna A.M., Busi K.B., Ramasubramanian B., Reddy V.S., Samanta A., Ramakrishna S., Ghosh S., Chakrabortty S., Dalapati G.K.
Article, Memories - Materials, Devices, Circuits and Systems, 2024, DOI Link
View abstract ⏷
High-quality copper oxide (CuO) thin films were deposited on the silicon (Si) substrate at the room temperature using the physical vapour deposition (PVD) technique named radio frequency (RF) sputtering. The copper-oxide thin-films were single crystalline and of uniform thickness. Subsequently, the influence of growth pressure (low gas pressure - 3 mTorr and high gas pressure - 100 mTorr) and post growth annealing at different temperatures (300 °C to 700 °C) were investigated to understand the microstructural and morphological changes of the thin film. With the influence of growth pressure and post thermal annealing temperature, significant changes in crystallinity, surface roughness, and surface oxidation rate of the CuO thin film were detected, which were adequately analyzed via several characterization techniques. X-ray diffraction (XRD) patterns revealed the phase formation with good crystallinity of the film, which is substantiated by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) characterization. Atomic force microscopy (AFM) images disclosed that the surface roughness of the film and grain size. By gaining insights into the structural and surface properties of CuO/Si thin films, this research presents new prospects for tuning of CuO phases, structures, and compositions for multifunctional applications.
Rational Design of Asymmetric Spinel/Defect Spinel (ZnMn2O4/Cu1.5Mn1.5O4) Nanocomposite-Based Supercapacitor Devices for Efficient Energy Storage with Improved Cycle Stability
Sivaguru G., Ghorui U.K., Girirajan M., Dalapati G.K., Maram P.S., Ghosh S., Sangaraju S., Chakrabortty S.
Article, ACS Applied Energy Materials, 2024, DOI Link
View abstract ⏷
The increasing global demand for energy solutions has created the necessity for innovative nanocomposite materials for efficient energy storage applications. This urgency is driving significant advancements in energy storage technologies, raising hope for the future of energy sectors. Supercapacitors (SCs), high-performance electrochemical storage devices, have earned considerable attention to address these challenges. In this article, we have demonstrated a cost-effective, easily obtainable trimetallic spinel/defect-spinel oxide ZnMn2O4/Cu1.5Mn1.5O4 (ZMO/CMO) nanocomposite through a facile one-step solvothermal synthesis process. This nanocomposite demonstrated exceptional charge storage capabilities. The charge storage mechanism was established by using Dunn’s method, which reveals the diffusive nature of the electrode material. The ZMO/CMO nanocomposite exhibits an impressive specific capacitance of 468.1 F/g at 0.5 A/g, with 84% capacity retention even after 20000 cycles, which was attributed to the oxygen vacancies within the defect spinel structure. Moreover, we fabricated an asymmetric device utilizing ZMO/CMO as the cathode and activated carbon (AC) as the anode. This device attained an energy density of 48.1Wh/kg and a power density of 700 W/kg with excellent cycling stability, as mentioned before. Furthermore, our study featured its ability to power a standard LED light.
Anion-Exchange Membrane Water Electrolyzers for Green Hydrogen Generation: Advancement and Challenges for Industrial Application
Ghorui U.K., Sivaguru G., Teja U.B., Aswathi M., Ramakrishna S., Ghosh S., Dalapati G.K., Chakrabortty S.
Review, ACS Applied Energy Materials, 2024, DOI Link
View abstract ⏷
Hydrogen is emerging as a strong contender for a feasible future energy carrier in the clean energy race, due to its high energy density and clean burning nature. However, to account for the environmental and energy challenges, its production must be sustainable and cost-efficient. Currently, hydrogen is generated from various feedstocks such as ammonia, methane, natural gas, biomass, smaller organic molecules, and water. These feedstocks undergo different catalytic processes, including catalytic decomposition, electrolysis, steam reforming, pyrolysis, gasification, and photoassisted methods such as photoelectrochemical, biophotolysis, and photocatalysis, etc. Among all, the research on water electrolysis has garnered much attention because of their carbon free green hydrogen production with the use of water electrolyzers (WEs). On the basis of recent reports from the International Renewable Energy Agency (IREA), the major types of water electrolyzers used in the industry are alkaline water electrolyzers (AWE), proton-exchange membrane water electrolyzers (PEMWEs), and anion-exchange membrane water electrolyzer (AEMWE). Among them, AWEs and PEMWEs have their inherent drawbacks which need attention. AEMWEs can be considered as a promising alternative by integrating the advantages of both AWEs and PEMWEs into one device. In this review, we have focused on the core ideas of AEMWEs, where the recent scientific and engineering breakthroughs are highlighted. It points out the importance of eliminating the gap between electrodes (i.e., zero gap concept) and identifies areas that need further development to push AEMWE technology forward. AEMWEs offer advantages such as higher operating current densities and pressures, comparable Faradaic efficiencies (>90%), and the utilization of nonprecious metal catalysts along with pure water feed. Along with all these, we have also focused on the advancements and deterioration of AEMs. Additionally, it provides a concise overview of AEMWE membrane performance and offers a detailed examination of developments in electrolyte feeding and the utilization of nonprecious group metal (non-PGM) electrocatalysts.
A new insight on surface chemistry and redox species of transition metal (Fe, Mn) doped CeO2-SnO2/Al2O3 nanocomposites for automobile emission control
Jayachandran V., Palanisami S., Paneerselvam J., Elango M., Chakrabortty S., Ghosh S., Albaqami M.D., Mohammad S., Sangaraju S.
Article, Journal of Environmental Chemical Engineering, 2024, DOI Link
View abstract ⏷
The ceria-tin/alumina mixed metal oxides (Ce/Sn =1) with different proportions of Fe & Mn dopants were synthesized and investigated in detailed approach for diesel emission reduction. The dopants created structural defects enhancing the oxygen ion mobility for exhaust treatment. The existence of surface-active oxygen sites and oxygen ion vacancy sites generated for charge compensation due to reduction of Ce4+, Sn4+ and dopants incorporation evidenced from XPS analysis. The Mn doped sample holds better physicochemical properties than Fe doped sample. The Mn doped sample with higher surface area of about 101.32 m2 g−1 exhibits greater active sites for better catalytic activity. The redox couples in the Mn-doped sample Ce4+/Ce3+, Sn4+/Sn2+, and Mn3+/Mn2+ helps in oxygen regeneration to contribute to exhaust treatment by oxygen ion conduction from bulk to the surface. This sample exhibited the 92 % of NOx reduction and proved to be a dynamic candidate for diesel emission reduction.
Aqueous based ultra-small magnetic Cr-doped CdSe quantum dots as a potential dual imaging probe in biomedicine
Bandaru S., George N., Sharma B., Palanivel M., Mukherjee A., Wu W.-Y., Ghosh K.K., Ball W.B., Gulyas B., Padmanabhan P., Ghosh S., Chakrabortty S.
Article, Biomaterials Science, 2024, DOI Link
View abstract ⏷
The substitution of semiconductor quantum dots (QDs) by a small number of transition-metal ions with magnetic properties gives rise to magnetic-doped semiconductors. With a balance of optical and magnetic properties, these magnetic semiconductors are widely used in spintronics, bioimaging and magnetic resonance imaging (MRI) applications. To facilitate their usage in bio-applications, it is critical to synthesize water-soluble magnetic QDs with a stabilized structure while maintaining their optical and magnetic properties. Here in our work, we have developed a facile substituted synthetic route to achieve Cr-doped CdSe (Cr-CdSe) via hydrothermal method. The effects of doping on the structural, optical, and magnetic properties of Cr-CdSe were studied using X-ray diffraction, UV-visible spectroscopy, and photoluminescence lifetime. We then explored their chemical nature and change in morphology with an increase in doping concentration via X-ray photoelectron spectroscopy and transmission electron microscopy. Water-soluble QDs have been used as bioimaging probes for the past few decades due to their strong fluorescence, photostability and improved tissue or cellular penetration. However, incorporating magnetic material into a fluorescent entity harnesses the ability to control the strengths of both modalities, which enhances diagnostic accuracy and facilitates its application in bio-systems, especially in early accurate diagnosis. Finally, we demonstrate the competency of Cr-CdSe as a dual-imaging probe with fluorescent cellular imaging and MRI applications.
Visible light-induced denitrogenative annulation reaction of 1,2,3-benzotriazin-4(3H)-ones with alkenes and alkynes via electron donor-acceptor (EDA) complex formation: a sustainable approach to isoindolinone and isoquinolinone synthesis
Article, Organic Chemistry Frontiers, 2024, DOI Link
View abstract ⏷
An efficient method for the synthesis of isoindolinones and isoquinolinones from 1,2,3-benzotriazin-4(3H)-ones under visible light is described. The reaction of 1,2,3-benzotriazin-4(3H)-ones with activated alkenes such as acrylonitrile, vinyl ketone, acrylates and vinyl sulfones in the presence of DIPEA under blue LED light irradiation gave isoindolinones in good to high yields. In a similar manner, the reaction of aromatic terminal alkynes with 1,2,3-benzotriazin-4(3H)-ones gave 3-substituted isoquinolinones. This method avoids the use of any metal or external photocatalysts and is believed to proceed via electron donor-acceptor (EDA) complex formation facilitated by DIPEA and 1,2,3-benzotriazin-4(3H)-ones. The practical applicability of these reactions is also demonstrated by performing gram-scale synthesis of isoquinolinones and isoindolinones. Moreover, the utility of this method was showcased through the synthesis of an anxiolytic drug pazinaclone analogue in high yield.
Mitochondrial phospholipid transport: Role of contact sites and lipid transport proteins
Mavuduru V.A., Vadupu L., Ghosh K.K., Chakrabortty S., Gulyas B., Padmanabhan P., Ball W.B.
Review, Progress in Lipid Research, 2024, DOI Link
View abstract ⏷
One of the major constituents of mitochondrial membranes is the phospholipids, which play a key role in maintaining the structure and the functions of the mitochondria. However, mitochondria do not synthesize most of the phospholipids in situ, necessitating the presence of phospholipid import pathways. Even for the phospholipids, which are synthesized within the inner mitochondrial membrane (IMM), the phospholipid precursors must be imported from outside the mitochondria. Therefore, the mitochondria heavily rely on the phospholipid transport pathways for its proper functioning. Since, mitochondria are not part of a vesicular trafficking network, the molecular mechanisms of how mitochondria receive its phospholipids remain a relevant question. One of the major ways that hydrophobic phospholipids can cross the aqueous barrier of inter or intraorganellar spaces is by apposing membranes, thereby decreasing the distance of transport, or by being sequestered by lipid transport proteins (LTPs). Therefore, with the discovery of LTPs and membrane contact sites (MCSs), we are beginning to understand the molecular mechanisms of phospholipid transport pathways in the mitochondria. In this review, we will present a brief overview of the recent findings on the molecular architecture and the importance of the MCSs, both the intraorganellar and interorganellar contact sites, in facilitating the mitochondrial phospholipid transport. In addition, we will also discuss the role of LTPs for trafficking phospholipids through the intermembrane space (IMS) of the mitochondria. Mechanistic insights into different phospholipid transport pathways of mitochondria could be exploited to vary the composition of membrane phospholipids and gain a better understanding of their precise role in membrane homeostasis and mitochondrial bioenergetics.
A Review on the Fate of Microplastics: Their Degradation and Advanced Analytical Characterization
Bandaru S., Ravipati M., Busi K.B., Phukan P., Bag S., Chandu B., Dalapati G.K., Biring S., Chakrabortty S.
Review, Journal of Polymers and the Environment, 2024, DOI Link
View abstract ⏷
Today, the world is struggling with the colossal amount of microplastics (MPs) due to the tremendous increase in the global production. Presence of MPs in the water samples, biological samples, and its potential to carry lethal chemicals raised the interest on better management of MPs. However, an effective degradation methodology is necessary to decrease the prolonged lifetime of such polymeric materials. So far, very limited reports are available on the degradation methods such as photo-oxidation, biodegradation, photo-thermal oxidative process, subsequent mechanisms involved during the degradation of MPs. Many critical challenges pertaining to those are poorly understood. Particularly, the extraction process, reliable methods to degrade MPs and their analytical techniques, level of MPs contamination in commercially caught fishes and the population at large. Here, we have revisited shortly on current MPs extraction process, various degradation methods using catalyst with their respective mechanisms. Also, the role of most common analytical methods/tools, to identify, analyse the degraded product from MPs, both environment samples and experimental samples, were elaborated. Finally, the solutions to overcome the problems were identified. Graphical Abstract: (Figure presented.)
Facile synthesis of WSe2/PEG nanostructures as a highly efficient with superior photocatalytic performance
Vijayakumar G., Subba Reddy A., Bandaru S., Chakrabortty S., Habila M.A., Arjun Kumar B., Sangaraju S.
Article, Inorganic Chemistry Communications, 2024, DOI Link
View abstract ⏷
Recent research has concentrated on developing efficient and cost-effective co-catalysts to enhance photocatalytic applications, which are prominent among the various emerging techniques for harnessing easily accessible energy sources. The present work focuses on the hydrothermal approach to fabricate and thoroughly characterize tungsten selenium (WSe2) nanoparticles using polyethylene glycol (PEG-4000) as their surfactant. The samples underwent advanced characterizations such as SEM and HRTEM to examine morphology, X-ray diffraction (XRD) to validate phase and crystal structure, photoluminescence (PL) and Raman studies for defect density determination, Fourier transform infrared (FTIR) spectroscopy for analyzing functional groups and bonds, and XPS for insights into elemental composition and chemical state of the hybrid nanostructures. A comparative analysis was conducted, utilizing both bare WSe2 and WSe2/PEG nanostructures, to observe their enhanced photocatalytic degradation efficiency and degradation kinetics on RhB. The superior photocatalytic performances were attributed to enhanced pore size and reduced defect density in the WSe2/PEG nanostructures.
Mitochondrial Reactive Oxygen Species in Infection and Immunity
Mukherjee A., Ghosh K.K., Chakrabortty S., Gulyas B., Padmanabhan P., Ball W.B.
Review, Biomolecules, 2024, DOI Link
View abstract ⏷
Reactive oxygen species (ROS) contain at least one oxygen atom and one or more unpaired electrons and include singlet oxygen, superoxide anion radical, hydroxyl radical, hydroperoxyl radical, and free nitrogen radicals. Intracellular ROS can be formed as a consequence of several factors, including ultra-violet (UV) radiation, electron leakage during aerobic respiration, inflammatory responses mediated by macrophages, and other external stimuli or stress. The enhanced production of ROS is termed oxidative stress and this leads to cellular damage, such as protein carbonylation, lipid peroxidation, deoxyribonucleic acid (DNA) damage, and base modifications. This damage may manifest in various pathological states, including ageing, cancer, neurological diseases, and metabolic disorders like diabetes. On the other hand, the optimum levels of ROS have been implicated in the regulation of many important physiological processes. For example, the ROS generated in the mitochondria (mitochondrial ROS or mt-ROS), as a byproduct of the electron transport chain (ETC), participate in a plethora of physiological functions, which include ageing, cell growth, cell proliferation, and immune response and regulation. In this current review, we will focus on the mechanisms by which mt-ROS regulate different pathways of host immune responses in the context of infection by bacteria, protozoan parasites, viruses, and fungi. We will also discuss how these pathogens, in turn, modulate mt-ROS to evade host immunity. We will conclude by briefly giving an overview of the potential therapeutic approaches involving mt-ROS in infectious diseases.
Recent Advances in Research from Nanoparticle to Nano-Assembly: A Review
Bandaru S., Arora D., Ganesh K.M., Umrao S., Thomas S., Bhaskar S., Chakrabortty S.
Review, Nanomaterials, 2024, DOI Link
View abstract ⏷
The careful arrangement of nanomaterials (NMs) holds promise for revolutionizing various fields, from electronics and biosensing to medicine and optics. This review delves into the intricacies of nano-assembly (NA) techniques, focusing on oriented-assembly methodologies and stimuli-dependent approaches. The introduction provides a comprehensive overview of the significance and potential applications of NA, setting the stage for review. The oriented-assembly section elucidates methodologies for the precise alignment and organization of NMs, crucial for achieving desired functionalities. The subsequent section delves into stimuli-dependent techniques, categorizing them into chemical and physical stimuli-based approaches. Chemical stimuli-based self-assembly methods, including solvent, acid–base, biomolecule, metal ion, and gas-induced assembly, are discussed in detail by presenting examples. Additionally, physical stimuli such as light, magnetic fields, electric fields, and temperature are examined for their role in driving self-assembly processes. Looking ahead, the review outlines futuristic scopes and perspectives in NA, highlighting emerging trends and potential breakthroughs. Finally, concluding remarks summarize key findings and underscore the significance of NA in shaping future technologies. This comprehensive review serves as a valuable resource for researchers and practitioners, offering insights into the diverse methodologies and potential applications of NA in interdisciplinary research fields.
A review on the role of nanotechnology in the development of near-infrared photodetectors: materials, performance metrics, and potential applications
Review, Journal of Materials Science, 2023, DOI Link
View abstract ⏷
This review article focuses on the role of nanotechnology (NT) in the development of advanced organic and inorganic photodetectors and their potential applications in the coming decades. We initiate the article with an overview of NT and potential applications of Nanotechnology in the twenty-first century ranging from Semiconductor manufacturing to Medical Imaging to Renewable energy to Quantum computing to Opto-electronics. The second part of the article delved into specific details on the role of nanotechnology and nanomaterials in developing advanced Photodetectors (PDs) and specifically discussing the internal functioning of near-infrared (NIR) photodetectors. Subsequently we focused on the performance metrics of PDs and types of PDs namely Organic Photodetectors (OPD) and Inorganic Photodetectors (IPD). We continued our in-depth discussion on OPDs and IPDs elaborating their structural features, operation mechanisms, types, performance optimization and role of functional nanomaterials. The final part of this review focuses on key applications of photodetectors e.g., retinal implant, biomedical imaging, personalized health monitoring, telecommunication, and military applications etc. Finally, we concluded the review paper discussing future opportunities and challenges regarding applications of NIR photodetectors in the twenty-first century. Graphical Abstract: [Figure not available: see fulltext.]
Maximizing solar energy production in ASEAN region: Opportunity and challenges
Kumar Dalapati G., Ghosh S., Sherin P A T., Ramasubramanian B., Samanta A., Rathour A., Kin Shun Wong T., Chakrabortty S., Ramakrishna S., Kumar A.
Article, Results in Engineering, 2023, DOI Link
View abstract ⏷
The Southeast Asian (SEA) region has witnessed a relentless surge in energy demand, driven by rapid urbanization, industrialization, and economic growth. In response, the exploration and development of renewable energy sources have gained significant attention. Among these sources, solar energy has emerged as a highly promising candidate due to its remarkable growth rate. This comprehensive review article aims to analyze the challenges and opportunities involved in maximizing solar energy production in the SEA region. The article commences with a succinct introduction to electromagnetic wave spectra and emphasizes the significance of visible spectra. It then provides a comprehensive examination of gross horizontal irradiance (GHI) patterns across the SEA region. A systematic tabulation is presented, organizing the current and potential solar energy installations and outputs of ASEAN countries. The article explores the deployment of hybrid photovoltaic (PV) systems, particularly floating PV installations, as an effective strategy to reduce dependence on fossil fuels. Moreover, the utilization of Supervisory Control and Data Acquisition (SCADA) systems for optimizing solar PV output is investigated. The article further delves into critical maintenance protocols, encompassing corrective, emergency, preventive, and predictive measures, and explores the levelized cost of electricity (LCOE) to assess the profitability of solar PV installations. Lastly, the leadership of Malaysia, Indonesia, and Singapore in solar PV research is highlighted, with a specific focus on building integrated PV and floating PV research. By addressing these, this review article offers valuable insights into the challenges and opportunities for advancing solar energy production in the SEA region.
Functionalized Graphene-Incorporated Cupric Oxide Charge-Transport Layer for Enhanced Photoelectrochemical Performance and Hydrogen Evolution
Krishna A.M.S., Ramasubramanian B., Haseena S., Bamola P., Sharma H., Mahata C., Chroneos A., Krishnamurthy S., Ravva M.K., Chandu B., Lim Y.-F., Kumar A., Ramakrishna S., Biring S., Chakrabortty S., Dalapati G.K.
Article, Catalysts, 2023, DOI Link
View abstract ⏷
The production of hydrogen (H2) through photoelectrochemical water splitting (PEC-WS) using renewable energy sources, particularly solar light, has been considered a promising solution for global energy and environmental challenges. In the field of hydrogen-scarce regions, metal oxide semiconductors have been extensively researched as photocathodes. For UV-visible light-driven PEC-WS, cupric oxide (CuO) has emerged as a suitable photocathode. However, the stability of the photocathode (CuO) against photo-corrosion is crucial in developing CuO-based PEC cells. This study reports a stable and effective CuO and graphene-incorporated (Gra-COOH) CuO nanocomposite photocathode through a sol-gel solution-based technique via spin coating. Incorporating graphene into the CuO nanocomposite photocathode resulted in higher stability and an increase in photocurrent compared to bare CuO photocathode electrodes. Compared to cuprous oxide (Cu2O), the CuO photocathode was more identical and thermally stable during PEC-WS due to its high oxidation number. Additionally, the CuO:Gra-COOH nanocomposite photocathode exhibited a H2 evolution of approximately 9.3 µmol, indicating its potential as a stable and effective photocathode for PEC-WS. The enhanced electrical properties of the CuO:Gra-COOH nanocomposite exemplify its potential for use as a charge-transport layer.
Highly Monodisperse, Size Tunable Glucosamine Conjugated CdSe Quantum Dots for Enhanced Cellular Uptake and Bioimaging
Bandaru S., Palanivel M., Ravipati M., Wu W.-Y., Zahid S., Halkarni S.S., Dalapati G.K., Ghosh K.K., Gulyas B., Padmanabhan P., Chakrabortty S.
Article, ACS Omega, 2023, DOI Link
View abstract ⏷
Semiconductor quantum dots (QDs) have been used in a variety of applications ranging from optoelectronics to biodiagnostic fields, primarily due to their size dependent fluorescent nature. CdSe nanocrystals (NCs) are generally synthesized via a hot injection method in an organic solvent. However, such NCs are insoluble in water and therefore preclude the direct usage toward biological systems. Thus, the preparation of more biocompatible water-soluble QDs with a high photoluminescent quantum yield (PLQY) is extremely important for imaging applications. Although previous literature has detailed on the synthesis of CdSe NCs in water, they suffer from poor size distribution and very low PLQY. The complex formation mechanism of CdSe NCs in an aqueous environment adversely affects the quality of NCs due to the presence of OH-, H+, and H2O moieties. Here in this article, we have presented the facile hydrothermal approach to obtain size tunable (2.9-5.1 nm), aqueous CdSe NCs with a narrow emission profile having ∼40 nm fwhm with 56% PLQY. Physicochemical properties of the synthesized water-soluble CdSe NCs were studied with the help of UV-vis, PL, XRD, FTIR, XPS, and HR-TEM analysis. Furthermore, the surface of the synthesized CdSe NCs was modified with d-glucosamine via EDC and NHS coupling to obtain a stable, biocompatible bioimaging probe. Furthermore, we demonstrated that their successful bioconjugation with glucosamine could facilitate effective internalization into the cellular matrix.
Surface Ligand Influences the Cu Nanoclusters as a Dual Sensing Optical Probe for Localized pH Environment and Fluoride Ion
Busi K.B., Das S., Palanivel M., Ghosh K.K., Gulyas B., Padmanabhan P., Chakrabortty S.
Article, Nanomaterials, 2023, DOI Link
View abstract ⏷
Functional metal nanomaterials, especially in the nanocluster (NC) size regime, with strong fluorescence, aqueous colloidal stability, and low toxicity, necessitate their application potential in biology and environmental science. Here, we successfully report a simple cost-effective method for red-/green-color-emitting protein/amino-acid-mediated Cu NCs in an aqueous medium. As-synthesized Cu NCs were characterized through UV-Vis absorption spectroscopy, fluorescence spectroscopy, time-resolved photoluminescence, dynamic light scattering, zeta potential, transmission electron microscopy and X-ray photoelectron spectroscopy. The optical properties of both Cu NCs responded linearly to the variation in pH in the neutral and alkaline ranges, and a robust pH reversible nature (between pH 7 and 11) was observed that could be extended to rapid, localized pH sensor development. However, a contrasting pH response nature between protein–Cu NCs and amino acid–Cu NCs was recorded. The alteration in protein secondary structure and strong binding nature of the surfactants were suggested to explain this behavior. Furthermore, we investigated their use as an efficient optical probe for fluoride ion detection. The limit of detection for protein–Cu NCs is 6.74 µM, whereas the limit of detection for amino acid–Cu NCs is 4.67 µM. Thus, it is anticipated that ultrasmall Cu NCs will exhibit promise in biological and environmental sensing applications.
Developing highly reliable SERS substrates based on Ag grown on alumina nanomeshes anodized under 1 V for efficiently sensing Raman-active molecules
Liu C.-Y., Ram R., Kolaru R.B., Chang S.-H., Chakrabortty S., Lin Y.-N., Chu C.-S., Biring S.
Article, Sensors and Actuators B: Chemical, 2023, DOI Link
View abstract ⏷
We have developed silver-nanostructures grown on anodic alumina nanomesh (AAN) films to create new-type substrates for surface-enhanced Raman scattering (SERS). AAN with uniform thin sidewall of ∼ 5 nm was fabricated by anodizing Al sheets at 1 V in 6% H3PO4 solution. Subsequent AC electrochemical deposition of silver created an array of nanoparticles or nano-islands depending on growth time. The particle-island transition is non-monotonic evolution, since metal growth and dissolution compete in AC electrodeposition process. Systematic SERS study on various Ag-AAN films with trial probes of adenine solutions reveals collective contribution of electron-plasma oscillation and surface area of silver nanostructures in Raman enhancements. SERS signals are primarily contributed by surface area under excitation wavelength of 532 nm (away from plasmonic resonance). The average correlation coefficient between the SERS intensity and surface area was 0.85, indicating robust correlation. This value was reduced to 0.61 under excitation wavelength of 633 nm (closer to plasmonic resonance). Furthermore, increased Ag-deposition reduced the relative standard deviation of SERS intensities and thus improved both the uniformity and quality consistency of SERS substrates. Therefore, fabrication of SERS substrate with larger Ag surface area under similar SERS enhancement factors is suggested for high throughput in commercial sectors.
Potential impact of various surface ligands on the cellular uptake and biodistribution characteristics of red, green, and blue emitting Cu nanoclusters
Busi K.B., Palanivel M., Jyothi K., LaiGuan Zoey F., Zahid S., Ghosh K.K., Agrawalla B.K., Gulyas B., Halkarni S.S., Thondamal M., Padmanabhan P., Chakrabortty S.
Article, RSC Advances, 2023, DOI Link
View abstract ⏷
Surface functionalization has a prominent influence on tuning/manipulating the physicochemical properties of nanometer scaled materials. Ultrasmall sized nanoclusters with very few atoms have received enormous attention due to their bright fluorescence, biocompatibility, lower toxicity, good colloidal stability and strong photostability. These properties make them suitable for diagnostic applications. In this work, we intend to study the effect of surface functional ligands on their biodistribution both in vitro and in vivo organelle systems for bioimaging applications.
Efficient wastewater treatment through nano-catalyst: The role of H2O2 and application in wide pH window
Bandaru S., Sen A., Pramanik G., Dalapati G.K., Biring S., Chakrabortty S.
Article, Environmental Advances, 2023, DOI Link
View abstract ⏷
The existence of toxic, non-biodegradable organic pollutants in wastewater has become an indisputable global observation of environmental problems. Degradation of organic pollutants using advanced oxidative processes like Fe-Fenton oxidation gained significant attention due to its potential in elimination of dye molecules. However, its narrow pH operating window (2.5–3.5 pH) and the residual iron limits their wide application. In this study, the bovine serum albumin encapsulated - copper sulfide (BSA-CuS) NPs for efficient degradation of organic pollutants was proposed. BSA-CuS NPs were successfully synthesized using simple thermal decomposition process and their physicochemical properties were thoroughly characterized using UV-Vis spectroscopy, XRD, HRTEM, FTIR and XPS. The synthesized CuS NPs shows superior performance in degrading of model organic dye in wide pH range when compared to the conventional Fe-Fenton systems. Later the influence of H2O2 sequential addition investigation revealed the enhanced degradation efficiency and its role was investigated with DFT hypothesis. The major contribution of active species responsible for the dye degradation was explored through scavenger study and reported the possible mechanism. Further the optimized condition was extended to real-time samples. Evaluation of recyclability, reduction in dissolved total organic carbon and antibacterial study evidence the potential of BSA-CuS as efficient and eco-friendly catalyst.
Copper based transparent solar heat rejecting film on glass through in-situ nanocrystal engineering of sputtered TiO2
Nawade A., Ramya K., Chakrabortty S., Bamola P., Sharma H., Sharma M., Chakraborty K., Ramakrishna S., Biring S., Shun Wong T.K., Kumar A., Mukhopadhyay S., Dalapati G.K.
Article, Ceramics International, 2022, DOI Link
View abstract ⏷
Sputter grown copper (Cu) and titanium dioxide (TiO2) based transparent solar heat rejecting film has been developed on glass substrates at room temperature for energy saving smart window applications. The performance of as-deposited ultra-thin TiO2/Cu/TiO2 multilayers was elucidated, wherein the visible transmittance of the multilayer significantly depends on the crystal quality of TiO2 layers. In-situ nanocrystal engineering of TiO2 films with optimized sputtering power improves crystallinity of nano-TiO2 domains. The transparent heat regulation (THR) coating with an average transmittance of ∼70% over the visible spectral regime and infra-red reflectance of ∼60% at 1200 nm was developed at room temperature. Optical characterization, X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM) have been utilized to analyze the crystallinity of TiO2 and quality of the multilayered structure. TiO2/Cu/TiO2 based prototype device has been demonstrated for the energy saving smart windows application.
Improved Charge Transport across Bovine Serum Albumin-Au Nanoclusters’ Hybrid Molecular Junction
Article, ACS Omega, 2022, DOI Link
View abstract ⏷
Proteins, a highly complex substance, have been an essential element in living organisms, and various applications are envisioned due to their biocompatible nature. Apart from proteins' biological functions, contemporary research mainly focuses on their evolving potential associated with nanoscale electronics. Here, we report one chemical doping process in model protein molecules (BSA) to modulate their electrical conductivity by incorporating metal (gold) nanoclusters on the surface or within them. The as-synthesized Au NCs incorporated inside the BSA (Au 1 to Au 6) were optically well characterized with UV-vis, time-resolved photoluminescence (TRPL), X-ray photon spectroscopy, and high-resolution transmission electron microscopy techniques. The PL quantum yield for Au 1 is 6.8%, whereas that for Au 6 is 0.03%. In addition, the electrical measurements showed ∼10-fold enhancement of conductivity in Au 6 (8.78 × 10-3S/cm), where maximum loading of Au NCs was predicted inside the protein matrix. We observed a dynamic behavior in the electrical conduction of such protein-nanocluster films, which could have real-time applications in preparing biocompatible electronic devices.
Engineering colloidally stable, highly fluorescent and nontoxic Cu nanoclusters via reaction parameter optimization
Busi K.B., Kotha J., Bandaru S., Ghantasala J.P., Haseena S., Bhamidipati K., Puvvada N., Ravva M.K., Thondamal M., Chakrabortty S.
Article, RSC Advances, 2022, DOI Link
View abstract ⏷
Metal nanoclusters (NCs) composed of the least number of atoms (a few to tens) have become very attractive for their emerging properties owing to their ultrasmall size. Preparing copper nanoclusters (Cu NCs) in an aqueous medium with high emission properties, strong colloidal stability, and low toxicity has been a long-standing challenge. Although Cu NCs are earth-abundant and inexpensive, they have been comparatively less explored due to their various limitations, such as ease of surface oxidation, poor colloidal stability, and high toxicity. To overcome these constraints, we established a facile synthetic route by optimizing the reaction parameters, especially altering the effective concentration of the reducing agent, to influence their optical characteristics. The improvement of the photoluminescence intensity and superior colloidal stability was modeled from a theoretical standpoint. Moreover, the as-synthesized Cu NCs showed a significant reduction of toxicity in both in vitro and in vivo models. The possibility of using such Cu NCs as a diagnostic probe toward C. elegans was explored. Also, the extension of our approach toward improving the photoluminescence intensity of the Cu NCs on other ligand systems was demonstrated.
Electronic structure and origin of intrinsic defects in sputtered HfTiO2 alloy dielectric on GaAs surface
Mahata C., Jyothirmai M.V., Ravva M.K., Chakrabortty S., Kim S., Biring S., Ramakrishna S., Dalapati G.K.
Article, Journal of Alloys and Compounds, 2022, DOI Link
View abstract ⏷
In this work, we have investigated the electronic structure and electrical properties of sputter-deposited high-k dielectrics grown on p-GaAs substrate with post-deposition annealing at 500 °C/N2 ambient. Capacitance-voltage results show that co-sputtered amorphous-HfTiO2 alloy dielectric can reduce interfacial dangling bonds. HRTEM and AR- X-ray photoelectron spectroscopy results confirmed the formation of a thin interfacial layer during sputter deposition. At the atomistic level, the surface reaction and electronic interface structure were investigated by density-functional theory (DFT) calculations. Using the HSE functional, theoretical calculations of bulk HfO2, a-TiO2, and HfTiO2 band gaps are found to be 5.27, 2.61, and 4.03 eV, respectively. Consequently, in the HfTiO2/GaAs interface, the valance band offset is found to be reduced to 1.04 eV compared to HfO2/GaAs structure valance band offset of 1.45 eV. Reduction in border trap density (~1011 V/cm2) was observed due to Ti atoms bridging between As-dangling bonds. The angle-resolved XPS analysis further confirmed Ti-O-As chemical bonding with very thin (~20 Å) dielectric layers.
Photovoltaic/catalysis integration toward a 100% renewable energy infrastructure
Ambati M.S.K., Dalapati G.K., Lawaniya R., Samanta A., Kumar A., Chakrabortty S.
Book chapter, Sulfide and Selenide Based Materials for Emerging Applications: Sustainable Energy Harvesting and Storage Technology, 2022, DOI Link
View abstract ⏷
Energy is an essentials input for a holistic socio-economic development in industrial applications, where effective infrastructure plays a pivotal role. Historically, studies on a renewable energy source (RES) have been increased both in absolute and relative terms. RES can be envisioned as important dimension by addressing the issues of fossil fuel depletion and a global warming. Alternatively, Hydrogen (H2) emerged as a renewable-energy-based product via integration of PV/PEC water splitting because it requires only 1.23 eV of thermodynamically potential to split the water. However, low efficiency of solar-to-hydrogen system (STH) as well as expensive photovoltaic (PV) cell is the main bottleneck for widespread commercial development of solar-based H2 production. The price of electrical energy should be four times lower than the price of commercial electricity because STH system is so reliant on rising electricity bills. Several engineered devices has been invented and had studied to get high stability along with low lost. The highest efficiency of PV-PEC device was recently achieved by fabrication of integrated system with a Ni electrode and a multi-junction GaInP/GaAs/Ge solar cell, which delivers a solar water splitting efficiency about 22.4%. Also, metal chalcogenide (sulfide/selenide) is one of the best options with a good stability, low cost, high efficiency of H2 and main application is solar energy harvesting and conversion. Synthesis of metal chalcogenide plays a major role in tunability of device infrastructure and results in increasing the efficiency. In this chapter we mainly focused on H2 such as infrastructure, synthesis, stability, STH efficiency of the devices along with their pros and cons.
The Multifarious Applications of Copper Nanoclusters in Biosensing and Bioimaging and Their Translational Role in Early Disease Detection
Busi K.B., Palanivel M., Ghosh K.K., Ball W.B., Gulyas B., Padmanabhan P., Chakrabortty S.
Review, Nanomaterials, 2022, DOI Link
View abstract ⏷
Nanoclusters possess an ultrasmall size, amongst other favorable attributes, such as a high fluorescence and long-term colloidal stability, and consequently, they carry several advantages when applied in biological systems for use in diagnosis and therapy. Particularly, the early diagnosis of diseases may be facilitated by the right combination of bioimaging modalities and suitable probes. Amongst several metallic nanoclusters, copper nanoclusters (Cu NCs) present advantages over gold or silver NCs, owing to their several advantages, such as high yield, raw abundance, low cost, and presence as an important trace element in biological systems. Additionally, their usage in diagnostics and therapeutic modalities is emerging. As a result, the fluorescent properties of Cu NCs are exploited for use in optical imaging technology, which is the most commonly used research tool in the field of biomedicine. Optical imaging technology presents a myriad of advantages over other bioimaging technologies, which are discussed in this review, and has a promising future, particularly in early cancer diagnosis and imaging-guided treatment. Furthermore, we have consolidated, to the best of our knowledge, the recent trends and applications of copper nanoclusters (Cu NCs), a class of metal nanoclusters that have been gaining much traction as ideal bioimaging probes, in this review. The potential modes in which the Cu NCs are used for bioimaging purposes (e.g., as a fluorescence, magnetic resonance imaging (MRI), two-photon imaging probe) are firstly delineated, followed by their applications as biosensors and bioimaging probes, with a focus on disease detection.
Photovoltaic/photo-electrocatalysis integration for green hydrogen: A review
Chatterjee P., Ambati M.S.K., Chakraborty A.K., Chakrabortty S., Biring S., Ramakrishna S., Wong T.K.S., Kumar A., Lawaniya R., Dalapati G.K.
Review, Energy Conversion and Management, 2022, DOI Link
View abstract ⏷
The Sun is an inexhaustible source of renewable energy, although under-utilized due to its intermittent nature. Hydrogen fuel is another clean, storable, and renewable energy as it can be readily produced by electrolysis of water, a naturally abundant resource. However, the necessary voltage for water electrolysis (>1.23 V) is high for the process to be cost effective, and therefore requires photoelectrocatalytic (PEC) cells for lowering the voltage. Powering the PEC cells with solar driven photovoltaic (PV) devices offers an all-clean efficient technology purely relying on renewable sources and therefore warrants large research attention. This review aims to provide an up to date account of the PV-PEC integrated technology for green hydrogen. We begin with the fundamentals of PV and water splitting technologies (electrolysis, photocatalysis, electrocatalysis (EC), photoelectrocatalysis (PEC)), as well as why and how the unassisted solar water splitting technology gradually progressed from PV with external electrolysers (PV-EC) to integration of PV with EC (IPV-EC) and PEC (PV-PEC). We then discuss the major challenges in PV-PEC integration and outline the major breakthroughs in design and materials development for high Solar to Hydrogen (STH) efficiency and long device lifetime. The importance of material selection and metal-oxide semiconductor nanostructures for PV-PEC integration are also discussed with a special focus on Cu-oxide as an emerging material. An outlook toward commercialization including the major guiding factors and related technologies (for e.g., PV-Thermal integration) that can maximize solar energy utilization to reduce payback time has been discussed.
A Carbon Nanodot Based Near-Infrared Photosensitizer with a Protein-Ruthenium Shell for Low-Power Photodynamic Applications
Naskar N., Liu W., Qi H., Stumper A., Fischer S., Diemant T., Behm R.J., Kaiser U., Rau S., Weil T., Chakrabortty S.
Article, ACS Applied Materials and Interfaces, 2022, DOI Link
View abstract ⏷
Near-infrared (NIR) light-activated photosensitization represents an encouraging therapeutic method in photodynamic therapy, especially for deep tissue penetration. In this context, two-photon activation, i.e., utilization of photons with relatively low energy but high photon flux for populating a virtual intermediate state leading to an excited state, is attractive. This concept would be highly advantageous in photodynamic therapy due to its minimal side effects. Herein, we propose that the combination of plasma protein serum albumin (HSA) containing several Ru complexes and NIR two-photon excitable carbon nanodots (Cdots), termed HSA-Ru-Cdots, provides several attractive features for enhancing singlet oxygen formation within the mitochondria of cancer cells stimulated by two-photon excitation in the NIR region. HSA-Ru-Cdot features biocompatibility, water solubility, and photostability as well as uptake into cancer cells with an endosomal release, which is an essential feature for subcellular targeting of mitochondria. The NIR two-photon excitation induced visible emission of the Cdots allows fluorescence resonance energy transfer (FRET) to excite the metal-to-ligand charge transfer of the Ru moiety, and fluorescence-lifetime imaging microscopy (FLIM) has been applied to demonstrate FRET within the cells. The NIR two-photon excitation is indirectly transferred to the Ru complexes, which leads to the production of singlet oxygen within the mitochondria of cancer cells. Consequently, we observe the destruction of filamentous mitochondrial structures into spheroid aggregates within various cancer cell lines. Cell death is induced by the long-wavelength NIR light irradiation at 810 nm with a low power density (7 mW/cm2), which could be attractive for phototherapy applications where deeper tissue penetration is crucial.
Fluorescent nanodiamond for nanotheranostic applications
Review, Microchimica Acta, 2022, DOI Link
View abstract ⏷
The interest in application of nanodiamonds as nanotheranostics is increasing rapidly over recent years. The combination of properties, such as high refractive index, low toxicity, inertness, high carrier capacity and rich surface functionalities, as well as unique magneto-optical properties of the nitrogen-vacancy centre, renders fluorescent nanodiamonds superior to other nanomaterials as nanotheranostics. In this review, the current state of research on the applications of nanodiamonds as theranostics where they have been utilised in combination with both diagnostics/imaging and therapy simultaneously is discussed. Firstly, a brief introduction to the current knowledge about the synthesis and properties of nitrogen-vacancy centre in nanodiamonds is given. Then, the underlying principles that are responsible for the magneto-optical properties of nitrogen-vacancy centre are explained. The majority of theranostic applications of nanodiamonds rely on the judicious engineering of their surface with bioactive molecules. In the following section, methods of engineering the surface of nanodiamonds while preserving their colloidal stability and their implication on in vitro and in vivo biocompatibility are described. Subsequently, the recent developments and applications of nanodiamond conjugates as photo-theranostics and non-targeted and targeted theranostics are critically discussed. Co-delivery of specifically tailored nanodiamonds with both diagnostic/imaging and therapeutic features can considerably contribute towards nanotheranostics-based personalized medicine. Graphical Abstract: [Figure not available: see fulltext.]
Efficient plastic recycling and remolding circular economy using the technology of trust–blockchain
Khadke S., Gupta P., Rachakunta S., Mahata C., Dawn S., Sharma M., Verma D., Pradhan A., Krishna A.M.S., Ramakrishna S., Chakrabortty S., Saianand G., Sonar P., Biring S., Dash J.K., Dalapati G.K.
Article, Sustainability (Switzerland), 2021, DOI Link
View abstract ⏷
Global plastic waste is increasing rapidly. In general, densely populated regions generate tons of plastic waste daily, which is sometimes disposed of on land or diverged to sea. Most of the plastics created in the form of waste have complex degradation behavior and are non-biodegradable by nature. These remain intact in the environment for a long time span and potentially originate complications within terrestrial and marine life ecosystems. The strategic management of plastic waste and recycling can preserve environmental species and associated costs. The key contribution in this work focuses on ongoing efforts to utilize plastic waste by introducing blockchain during plastic waste recycling. It is proposed that the efficiency of plastic recycling can be improved enormously by using the blockchain phenomenon. Automation for the segregation and collection of plastic waste can effectively establish a globally recognizable tool using blockchain-based applications. Collection and sorting of plastic recycling are feasible by keeping track of plastic with unique codes or digital badges throughout the supply chain. This approach can support a collaborative digital consortium for efficient plastic waste management, which can bring together multiple stakeholders, plastic manufacturers, government entities, retailers, suppliers, waste collectors, and recyclers.
Tin oxide for optoelectronic, photovoltaic and energy storage devices: A review
Dalapati G.K., Sharma H., Guchhait A., Chakrabarty N., Bamola P., Liu Q., Saianand G., Sai Krishna A.M., Mukhopadhyay S., Dey A., Wong T.K.S., Zhuk S., Ghosh S., Chakrabortty S., Mahata C., Biring S., Kumar A., Ribeiro C.S., Ramakrishna S., Chakraborty A.K., Krishnamurthy S., Sonar P., Sharma M.
Review, Journal of Materials Chemistry A, 2021, DOI Link
View abstract ⏷
Tin dioxide (SnO2), the most stable oxide of tin, is a metal oxide semiconductor that finds its use in a number of applications due to its interesting energy band gap that is easily tunable by doping with foreign elements or by nanostructured design such as thin film, nanowire or nanoparticle formation,etc., and its excellent thermal, mechanical and chemical stability. In particular, its earth abundance and non-toxicity make it very attractive for use in a number of technologies for sustainable development such as energy harvesting and storage. This article attempts to review the state of the art of synthesis and properties of SnO2, focusing primarily on its application as a transparent conductive oxide (TCO) in various optoelectronic devices and second in energy harvesting and energy storage devices where it finds its use as an electron transport layer (ETL) and an electrode material, respectively. In doing so, we discuss how tin oxide meets the requirements for the above applications, the challenges associated with these applications, and how its performance can be further improved by adopting various strategies such as doping with foreign metals, functionalization with plasma,etc.The article begins with a review on the various experimental approaches to doping of SnO2with foreign elements for its enhanced performance as a TCO as well as related computational studies. Herein, we also compare the TCO performance of doped tin oxide as a function of dopants such as fluorine (F), antimony (Sb), tantalum (Ta), tungsten (W), molybdenum (Mo), phosphorus (P), and gallium (Ga). We also discuss the properties of multilayer SnO2/metal/SnO2structures with respect to TCO performance. Next, we review the status of tin oxide as a TCO and an ETL in devices such as organic light emitting diodes (OLEDs), organic photovoltaics (OPV), and perovskite solar cells (including plasma treatment approaches) followed by its use in building integrated photovoltaic (BIPV) applications. Next, we review the impact of SnO2, mainly as an electrode material on energy storage devices starting from the most popular lithium (Li)-ion batteries to Li-sulfur batteries and finally to the rapidly emerging technology of supercapacitors. Finally, we also compare the performance of doped SnO2with gallium (Ga) doped zinc oxide (ZnO), the main sustainable alternative to SnO2as a TCO and summarize the impact of SnO2on circular economies and discuss the main conclusions and future perspectives. It is expected that the review will serve as an authoritative reference for researchers and policy makers interested in finding out how SnO2can contribute to the circular economy of some of the most desired sustainable and clean energy technologies including the detailed experimental methods of synthesis and strategies for performance enhancement.
Nano-structured CuO on Silicon Using a Chemical Bath Deposition Process and Sputter Seed Layer
Bandaru S., Mahata C., Chakrabortty S., Ghosh S., Algadi H., Ramakrishna S., Dalapati G.K.
Article, Journal of Electronic Materials, 2021, DOI Link
View abstract ⏷
Morphological changes of copper oxide (CuO) nano-structures have been studied in detail for renewable energy and electronic applications. The CuO nano-structures were grown on a silicon substrate via a two-stage process starting with radio frequency sputtering for the seed layer followed by chemical bath deposition. The study was focused on controlling the shape and size of the CuO nano-structures depending on various growth conditions, such as reaction time, growth temperature, and vertical/horizontal orientation of the substrate containing the sputtered-grown seed layer. Structural, optical, crystallographic, and morphological characteristics of the nano-structures were obtained through field-emission scanning electron microscopy, x-ray diffraction crystallographic analysis, and UV–Vis spectroscopy.
Erratum: Patchy amphiphilic dendrimers bind adenovirus and control its host interactions and in vivo distribution (ACS Nano (2019) 13:8 (8749-8759) DOI: 10.1021/acsnano.9b01484)
Wu Y., Li L., Frank L., Wagner J., Andreozzi P., Hammer B., D'Alicarnasso M., Pelliccia M., Liu W., Chakrabortty S., Krol S., Simon J., Landfester K., Kuan S.L., Stellacci F., Mullen K., Kreppel F., Weil T.
Erratum, ACS Nano, 2021, DOI Link
View abstract ⏷
On page 8753, the blood vessel background is missing in the last picture of Figure 3d. The corrected Figure 3d is as follows: (Figure Presented).
Recent developments in smart window engineering: from antibacterial activity to self-cleaning behavior
Book chapter, Energy Saving Coating Materials: Design, Process, Implementation and Recent Developments, 2020, DOI Link
View abstract ⏷
This chapter discusses about recent advancements on smart coating and their potential applications in smart window engineering. First part of this book-chapter will discuss about recent developments in Smart-window technology. It has potential to exhibit different applications using various sources such as light, heat, and voltage to produce unique properties. In comparison to normal static windows, smart windows can modulate solar transmittance of NIR and visible light depending on weather conditions and personal preferences of human beings inside the door. Although very few smart windows are commercially available in the market, their demand is not yet to be realized. On the other hand, latest engineered nanostructured materials contribute new opportunities for future smart window technology. Initially, this article will elaborate the antibacterial activities of smart coating technology. Antibacterial surfaces are of great importance due to their potential application in coating of medical devices and implants, paints, food packaging, transportation etc. Final section of this chapter will illustrate wettability research done on novel material surfaces including smart windows. Understanding solid–liquid interface at fundamental level is of tremendous implication due to their potential application in creating self-cleaning and self-lubricating surfaces. These types of advanced thin film surfaces can have multiple potential applications ranging from everyday life to advanced technological utilization such as transparent coating of smart windows to microfluidics to fabrication of advanced nano-biomaterials.
Nanoengineered Advanced Materials for Enabling Hydrogen Economy: Functionalized Graphene–Incorporated Cupric Oxide Catalyst for Efficient Solar Hydrogen Production
Dalapati G.K., Masudy-Panah S., Moakhar R.S., Chakrabortty S., Ghosh S., Kushwaha A., Katal R., Chua C.S., Xiao G., Tripathy S., Ramakrishna S.
Article, Global Challenges, 2020, DOI Link
View abstract ⏷
Cupric oxide (CuO) is a promising candidate as a photocathode for visible-light-driven photo-electrochemical (PEC) water splitting. However, the stability of the CuO photocathode against photo-corrosion is crucial for developing CuO-based PEC cells. This study demonstrates a stable and efficient photocathode through the introduction of graphene into CuO film (CuO:G). The CuO:G composite electrodes are prepared using graphene-incorporated CuO sol–gel solution via spin-coating techniques. The graphene is modified with two different types of functional groups, such as amine (-NH2) and carboxylic acid (-COOH). The -COOH-functionalized graphene incorporation into CuO photocathode exhibits better stability and also improves the photocurrent generation compare to control CuO electrode. In addition, -COOH-functionalized graphene reduces the conversion of CuO phase into cuprous oxide (Cu2O) during photo-electrochemical reaction due to effective charge transfer and leads to a more stable photocathode. The reduction of CuO to Cu2O phase is significantly lesser in CuO:G-COOH as compared to CuO and CuO:G-NH2 photocathodes. The photocatalytic degradation of methylene blue (MB) by CuO, CuO:G-NH2 and CuO:G-COOH is also investigated. By integrating CuO:G-COOH photocathode with a sol–gel-deposited TiO2 protecting layer and Au–Pd nanostructure, stable and efficient photocathode are developed for solar hydrogen generation.
Impact of surface chemistry and doping concentrations on biofunctionalization of GaN/Ga-in-N quantum wells
Naskar N., Schneidereit M.F., Huber F., Chakrabortty S., Veith L., Mezger M., Kirste L., Fuchs T., Diemant T., Weil T., Behm R.J., Thonke K., Scholz F.
Article, Sensors (Switzerland), 2020, DOI Link
View abstract ⏷
The development of sensitive biosensors, such as gallium nitride (GaN)-based quantum wells, transistors, etc., often makes it necessary to functionalize GaN surfaces with small molecules or eVen biomolecules, such as proteins. As a first step in surface functionalization, we have investigated silane adsorption, as well as the formation of very thin silane layers. In the next step, the immobilization of the tetrameric protein streptavidin (as well as the attachment of chemically modified iron transport protein ferritin (ferritin-biotin-rhodamine complex)) was realized on these films. The degree of functionalization of the GaN surfaces was determined by fluorescence measurements with fluorescent-labeled proteins; silane film thickness and surface roughness were estimated, and also other surface sensitive techniques were applied. The formation of a monolayer consisting of adsorbed organosilanes was accomplished on Mg-doped GaN surfaces, and also functionalization with proteins was achieved. We found that very high Mg doping reduced the amount of surface functionalized proteins. Most likely, this finding was a consequence of the lower concentration of ionizable Mg atoms in highly Mg-doped layers as a consequence of self-compensation effects. In summary, we could demonstrate the necessity of Mg doping for achieving reasonable bio-functionalization of GaN surfaces.
Polymer coated nanodiamonds as gemcitabine prodrug with enzymatic sensitivity for pancreatic cancer treatment
Ye W., Han H., Li H., Jin Q., Wu Y., Chakrabortty S., Weil T., Ji J.
Article, Progress in Natural Science: Materials International, 2020, DOI Link
View abstract ⏷
The fabrication of Gemcitabine (GEM) prodrug was reported to be an effective method to enhance its pancreatic cancer treatment efficiency. Here, a kind of nanocarbon-based materials, nanodiamond (ND), was selected as the nanocarrier of GEM, owing to its outstanding surface properties and non-cytotoxicity. The polyelectrolytes, polyethyleneimine and polyacrylic acid, were used to self-assemble outside ND surface through electrostatic forces, followed by attachment of polyethylene glycol to address better biocompatibility. GEM was conjugated with an enzyme-sensitive peptide gly-phe-leu-gly to build up the controlled release platform. From characterization results of dynamic laser scattering, zeta potential and transmission electron microscope, the significant improvement of ND stability in physiological condition was proved. Non-cytotoxicity of this functionalized ND carriers and cytotoxicity of the prodrug against BxPC-3 pancreatic cancer cells were indicated by methylthiazolyl tetrazolium (MTT) assay. In vivo experiments also revealed its superior anticancer effect compared with free GEM treatment. Therefore, the combination of polymer coated NDs with high surface capability and enzyme-responsive intracellular GEM release make it possible to realize higher treatment efficiency on pancreatic tumor therapy.
Somatostatin receptor mediated targeting of acute myeloid leukemia by photodynamic metal complexes for light induced apoptosis
Vegi N.M., Chakrabortty S., Zegota M.M., Kuan S.L., Stumper A., Rawat V.P.S., Sieste S., Buske C., Rau S., Weil T., Feuring-Buske M.
Article, Scientific Reports, 2020, DOI Link
View abstract ⏷
Acute myeloid leukemia (AML) is characterized by relapse and treatment resistance in a major fraction of patients, underlining the need of innovative AML targeting therapies. Here we analysed the therapeutic potential of an innovative biohybrid consisting of the tumor-associated peptide somatostatin and the photosensitizer ruthenium in AML cell lines and primary AML patient samples. Selective toxicity was analyzed by using CD34 enriched cord blood cells as control. Treatment of OCI AML3, HL60 and THP1 resulted in a 92, and 99 and 97% decrease in clonogenic growth compared to the controls. Primary AML cells demonstrated a major response with a 74 to 99% reduction in clonogenicity in 5 of 6 patient samples. In contrast, treatment of CD34+ CB cells resulted in substantially less reduction in colony numbers. Subcellular localization assays of RU-SST in OCI-AML3 cells confirmed strong co-localization of RU-SST in the lysosomes compared to the other cellular organelles. Our data demonstrate that conjugation of a Ruthenium complex with somatostatin is efficiently eradicating LSC candidates of patients with AML. This indicates that receptor mediated lysosomal accumulation of photodynamic metal complexes is a highly attractive approach for targeting AML cells.
Patchy Amphiphilic Dendrimers Bind Adenovirus and Control Its Host Interactions and in Vivo Distribution
Wu Y., Li L., Frank L., Wagner J., Andreozzi P., Hammer B., D'Alicarnasso M., Pelliccia M., Liu W., Chakrabortty S., Krol S., Simon J., Landfester K., Kuan S.L., Stellacci F., Mullen K., Kreppel F., Weil T.
Article, ACS Nano, 2019, DOI Link
View abstract ⏷
The surface of proteins is heterogeneous with sophisticated but precise hydrophobic and hydrophilic patches, which is essential for their diverse biological functions. To emulate such distinct surface patterns on macromolecules, we used rigid spherical synthetic dendrimers (polyphenylene dendrimers) to provide controlled amphiphilic surface patches with molecular precision. We identified an optimal spatial arrangement of these patches on certain dendrimers that enabled their interaction with human adenovirus 5 (Ad5). Patchy dendrimers bound to the surface of Ad5 formed a synthetic polymer corona that greatly altered various host interactions of Ad5 as well as in vivo distribution. The dendrimer corona (1) improved the ability of Ad5-derived gene transfer vectors to transduce cells deficient for the primary Ad5 cell membrane receptor and (2) modulated the binding of Ad5 to blood coagulation factor X, one of the most critical virus-host interactions in the bloodstream. It significantly enhanced the transduction efficiency of Ad5 while also protecting it from neutralization by natural antibodies and the complement system in human whole blood. Ad5 with a synthetic dendrimer corona revealed profoundly altered in vivo distribution, improved transduction of heart, and dampened vector sequestration by liver and spleen. We propose the design of bioactive polymers that bind protein surfaces solely based on their amphiphilic surface patches and protect against a naturally occurring protein corona, which is highly attractive to improve Ad5-based in vivo gene therapy applications.
Oxygen sensing PLIM together with FLIM of intrinsic cellular fluorophores for metabolic mapping
Kalinina S., Schaefer P., Breymayer J., Bisinger D., Chakrabortty S., Rueck A.
Conference paper, Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2018, DOI Link
View abstract ⏷
Otical imaging techniques based on time correlated single photon counting (TCSPC) has found wide applications in medicine and biology. Non-invasive and information-rich fluorescence lifetime imaging microscopy (FLIM) is successfully used for monitoring fluorescent intrinsic metabolic coenzymes as NAD(P)H (nicotinamide adenine dinucleotide (phosphate)) and FAD+ (flavin adenine dinucleotide) in living cells and tissues. The ratio between proteinbound and free coenzymes gives an information about the balance between oxidative phosphorylation and glycolysis in the cells. The changes of the ratio reflects major cellular disorders. A correlation exists between metabolic activity, redox ratio and fluorescence lifetime during stem cell differentiation, neurodegenerative diseases, and carcinogenesis. A multichannel FLIM detection system was designed for monitoring the redox state of NAD(P)H and FAD+ and other intrinsic fluorophores as protoporphyrin IX. In addition, the unique upgrade is useful to perform FLIM and PLIM (phosphorescence lifetime imaging microscopy) simultaneously. PLIM is a promising method to investigate oxygen sensing in biomedical samples. In detail, the oxygen-dependent quenching of phosphorescence of some compounds as transition metal complexes enables measuring of oxygen partial pressure (pO2). Using a two-channel FLIM/PLIM system we monitored intrinsic pO2 by PLIM simultaneously with NAD(P)H by FLIM providing complex metabolic and redox imaging of living cells. Physico-chemical properties of oxygen sensitive probes define certain parameters including their localisation. We present results of some ruthenium based complexes including those specifically bound to mitochondria.
Mitochondria Targeted Protein-Ruthenium Photosensitizer for Efficient Photodynamic Applications
Chakrabortty S., Agrawalla B.K., Stumper A., Vegi N.M., Fischer S., Reichardt C., Kogler M., Dietzek B., Feuring-Buske M., Buske C., Rau S., Weil T.
Article, Journal of the American Chemical Society, 2017, DOI Link
View abstract ⏷
Organelle-targeted photosensitization represents a promising approach in photodynamic therapy where the design of the active photosensitizer (PS) is very crucial. In this work, we developed a macromolecular PS with multiple copies of mitochondria-targeting groups and ruthenium complexes that displays highest phototoxicity toward several cancerous cell lines. In particular, enhanced anticancer activity was demonstrated in acute myeloid leukemia cell lines, where significant impairment of proliferation and clonogenicity occurs. Finally, attractive two-photon absorbing properties further underlined the great significance of this PS for mitochondria targeted PDT applications in deep tissue cancer therapy.
GaInN Quantum Wells as Optochemical Transducers for Chemical Sensors and Biosensors
Heinz D., Huber F., Spiess M., Asad M., Wu L., Rettig O., Wu D., Neuschl B., Bauer S., Wu Y., Chakrabortty S., Hibst N., Strehle S., Weil T., Thonke K., Scholz F.
Article, IEEE Journal of Selected Topics in Quantum Electronics, 2017, DOI Link
View abstract ⏷
In this paper, investigations on gallium indium nitride (GaInN) quantum well structures as optochemical transducers in (bio)chemical sensing are presented. In contrast to the conventional electrical read-out of III-nitride-based sensors, a purely optical photoluminescence read-out is performed. A significant spectral shift of the quantum well photoluminescence is observed with varying surface modification. The spectral photoluminescence shift can be attributed to an externally induced quantum confined Stark effect caused by the adsorbed species deposited on the quantum well surface. In order to improve the sensitivity of the transducer elements, different chemical surface treatments are studied. In particular, optical sensing experiments with reducing and oxidizing gases are performed in order to investigate the quantum well photoluminescence response. Additionally, optical investigations of the iron-storage molecule ferritin with varying iron load are presented. The iron load of this molecule is generally considered as a superior biomarker for severe illnesses, such as Alzheimer's disease. In contrast to conventional fluorescent labels, GaInN quantum wells provide a much more stable luminescence signal, and hence, are promising candidates for next generation bioanalytical sensor structures.
3D Time-lapse Imaging and Quantification of Mitochondrial Dynamics
Sison M., Chakrabortty S., Extermann J., Nahas A., James Marchand P., Lopez A., Weil T., Lasser T.
Article, Scientific Reports, 2017, DOI Link
View abstract ⏷
We present a 3D time-lapse imaging method for monitoring mitochondrial dynamics in living HeLa cells based on photothermal optical coherence microscopy and using novel surface functionalization of gold nanoparticles. The biocompatible protein-based biopolymer coating contains multiple functional groups which impart better cellular uptake and mitochondria targeting efficiency. The high stability of the gold nanoparticles allows continuous imaging over an extended time up to 3000 seconds without significant cell damage. By combining temporal autocorrelation analysis with a classical diffusion model, we quantify mitochondrial dynamics and cast these results into 3D maps showing the heterogeneity of diffusion parameters across the whole cell volume.
NIR-emitting and photo-thermal active nanogold as mitochondria-specific probes
Chakrabortty S., Sison M., Wu Y., Ladenburger A., Pramanik G., Biskupek J., Extermann J., Kaiser U., Lasser T., Weil T.
Article, Biomaterials Science, 2017, DOI Link
View abstract ⏷
We report a bioinspired multifunctional albumin derived polypeptide coating comprising grafted poly(ethylene oxide) chains, multiple copies of the HIV TAT derived peptide enabling cellular uptake as well as mitochondria targeting triphenyl-phosphonium (TPP) groups. Exploring these polypeptide copolymers for passivating gold nanoparticles (Au NPs) yielded (i) NIR-emitting markers in confocal microscopy and (ii) photo-thermal active probes in optical coherence microscopy. We demonstrate the great potential of such multifunctional protein-derived biopolymer coatings for efficiently directing Au NP into cells and to subcellular targets to ultimately probe important cellular processes such as mitochondria dynamics and vitality inside living cells.
Facet-to-facet linking of shape-anisotropic colloidal cadmium chalcogenide nanostructures
Ong X., Gupta S., Wu W.-Y., Chakrabortty S., Chan Y.
Article, Journal of Visualized Experiments, 2017, DOI Link
View abstract ⏷
Here, we describe a protocol that allows for shape-anisotropic cadmium chalcogenide nanocrystals (NCs), such as nanorods (NRs) and tetrapods (TPs), to be covalently and site-specifically linked via their end facets, resulting in polymer-like linear or branched chains. The linking procedure begins with a cation-exchange process in which the end facets of the cadmium chalcogenide NCs are first converted to silver chalcogenide. This is followed by the selective removal of ligands at their surface. This results in cadmium chalcogenide NCs with highly reactive silver chalcogenide end facets that spontaneously fuse upon contact with each other, thereby establishing an interparticle facet-tofacet attachment. Through the judicious choice of precursor concentrations, an extensive network of linked NCs can be produced. Structural characterization of the linked NCs is carried out via low- and high-resolution transmission electron microscopy (TEM), as well as energydispersive X-ray spectroscopy, which confirm the presence of silver chalcogenide domains between chains of cadmium chalcogenide NCs.
Hierarchical Multicomponent Nanoheterostructures via Facet-to-Facet Attachment of Anisotropic Semiconductor Nanoparticles
Gupta S., Wu W.-Y., Chakrabortty S., Li M., Wang Y., Ong X., Chan Y.
Article, Chemistry of Materials, 2017, DOI Link
View abstract ⏷
As performance and functionality requirements for solution-processed nanomaterials become more stringent and demanding, there is an ever-growing need for hierarchical nanostructures with sophisticated architecture and complex composition. However, the production of structurally complex nanomaterials is often not possible by direct synthesis. In this work, we describe synthetic methodology to covalently link presynthesized anisotropic semiconductor nanoparticles of different composition in a stoichiometrically controlled manner via specific facet sites at room temperature. We demonstrate that CdSe nanorods can be cojoined with CdTe tetrapods via a competitive cation-exchange process with Ag+ that results in linking between the tips of the tetrapod arms with only one end of each nanorod via a Ag2Se-Ag2Te interface. This selective linking was engineered by having a large fraction of CdSe nanorods present in the reaction, which sterically hindered homolinking between Ag2Se-tipped CdSe nanorods and Ag2Te-tipped CdTe tetrapods with themselves. Cation back-exchange with Cd2+ and a size-selective purification to remove unlinked products yields samples enriched in heterolinked CdTe tetrapod-CdSe nanorod structures. High-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy confirmed the structure and composition of the nanorod-linked tetrapods, while time-resolved and pump-dependent photoluminescence data were consistent with a type II band offset at the CdTe-CdSe interface. The synthetic approach to colloidal nanoheterostructures described here is highly distinct from traditional methods involving a series of nucleation and growth steps at elevated temperature.
Observation of an excitonic quantum coherence in CdSe nanocrystals
Dong S., Trivedi D., Chakrabortty S., Kobayashi T., Chan Y., Prezhdo O.V., Loh Z.-H.
Conference paper, Optics InfoBase Conference Papers, 2016, DOI Link
View abstract ⏷
Optical pump-probe spectroscopy with 6-fs pulses elucidates the 1Se1S3/2-1Se2S3/2 excitonic quantum coherence in CdSe nanocrystals. This coherence encodes hole migration over nanometer length scales and markedly alters the displacement amplitudes of coherent phonons.
Cation exchange synthesis of uniform PbSe/PbS core/shell tetra-pods and their use as near-infrared photodetectors
Mishra N., Mukherjee B., Xing G., Chakrabortty S., Guchhait A., Lim J.Y.
Article, Nanoscale, 2016, DOI Link
View abstract ⏷
In this work we explore the preparation of complex-shaped semiconductor nanostructures composed of different materials via a cationic exchange process in which the cations of the original semiconductor nanostructure are replaced by cations of different metals with preservation of the shape and the anionic framework of the nanocrystals. Utilizing this cation exchange method, we synthesized two new tetrapods for the first time: Cu2-xSe/Cu2-xS and PbSe/PbS, both prepared from CdSe/CdS tetrapods as 'templates'. We also fabricated near-infrared (NIR) photodetectors with a very simple architecture comprising a PbSe/PbS tetrapod layer between two Au electrodes on a glass substrate. When illuminated by a NIR laser, these devices are capable of achieving a responsivity of 11.9 A W-1 without the use of ligand-exchange processes, thermal annealing or hybrid device architecture. Transient absorption spectroscopy was carried out on these PbSe/PbS tetrapods, the results of which suggest that the branched morphology contributes in part to device performance. Investigation of the charge dynamics of the PbSe/PbS tetrapods revealed an extremely long-lived exciton recombination lifetime of ∼17 ms, which can result in enhanced photoconductive gain. Overall, these heterostructured tetrapods showcase simultaneously the importance of nanoparticle shape, band structure, and surface chemistry in the attainment of NIR photodetection.
Fluorescent Nanodiamond-Gold Hybrid Particles for Multimodal Optical and Electron Microscopy Cellular Imaging
Liu W., Naydenov B., Chakrabortty S., Wuensch B., Hubner K., Ritz S., Colfen H., Barth H., Koynov K., Qi H., Leiter R., Reuter R., Wrachtrup J., Boldt F., Scheuer J., Kaiser U., Sison M., Lasser T., Tinnefeld P., Jelezko F., Walther P., Wu Y., Weil T.
Article, Nano Letters, 2016, DOI Link
View abstract ⏷
There is a continuous demand for imaging probes offering excellent performance in various microscopy techniques for comprehensive investigations of cellular processes by more than one technique. Fluorescent nanodiamond-gold nanoparticles (FND-Au) constitute a new class of "all-in-one" hybrid particles providing unique features for multimodal cellular imaging including optical imaging, electron microscopy, and, and potentially even quantum sensing. Confocal and optical coherence microscopy of the FND-Au allow fast investigations inside living cells via emission, scattering, and photothermal imaging techniques because the FND emission is not quenched by AuNPs. In electron microscopy, transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) analysis of FND-Au reveals greatly enhanced contrast due to the gold particles as well as an extraordinary flickering behavior in three-dimensional cellular environments originating from the nanodiamonds. The unique multimodal imaging characteristics of FND-Au enable detailed studies inside cells ranging from statistical distributions at the entire cellular level (micrometers) down to the tracking of individual particles in subcellular organelles (nanometers). Herein, the processes of endosomal membrane uptake and release of FNDs were elucidated for the first time by the imaging of individual FND-Au hybrid nanoparticles with single-particle resolution. Their convenient preparation, the availability of various surface groups, their flexible detection modalities, and their single-particle contrast in combination with the capability for endosomal penetration and low cytotoxicity make FND-Au unique candidates for multimodal optical-electronic imaging applications with great potential for emerging techniques, such as quantum sensing inside living cells.
Facet to Facet Linking of Shape Anisotropic Inorganic Nanocrystals with Site Specific and Stoichiometric Control
Chakrabortty S., Guchhait A., Ong X., Mishra N., Wu W.-Y., Jhon M.H., Chan Y.
Article, Nano Letters, 2016, DOI Link
View abstract ⏷
Nonclassical growth mechanisms such as self-assembly and oriented attachment are effective ways to build complex nanostructures from simpler ones. In the latter case, the nanoparticle components are electronically coupled; however, control over the attachment between nanoparticles is highly challenging and generally requires a delicate balance between dipole-, ligand-, and solvent-based interactions. To this end, we perform incomplete cation exchange with Ag+ (Cu+) on CdSe-seeded CdS nanorods and tetrapods to exclusively convert their tips into small Ag2S (Cu2S) domains. Selective removal of the ligands from these inorganic domains results in spontaneous, site-specific bridging of the nanoparticles. Using this method, we demonstrate the fabrication of polymer-like linear and branched nanoparticles with enhanced electrical properties, as well as the stoichiometric formation of nanoparticle homo- and heterodimers and tetramers. We show that linked structures can then be completely cation exchanged with Pb2+ to generate PbSe/PbS-based nanostructured photodetector media with enhanced properties.
Solution-Processed 2D PbS Nanoplates with Residual Cu2S Exhibiting Low Resistivity and High Infrared Responsivity
Wu W.-Y., Chakrabortty S., Guchhait A., Wong G.Y.Z., Dalapati G.K., Lin M., Chan Y.
Article, Chemistry of Materials, 2016, DOI Link
View abstract ⏷
We report the synthesis of colloidal 2D PbS nanoplates with residual Cu2S domains via a partial cation-exchange process involving Pb2+ and presynthesized hexagonal Cu2S nanoplates with an average thickness of ∼3 nm and edge lengths of ∼150 nm. Different from previously reported PbS nanosheets whose basal planes are ±{100}PbS, our approach yields nanoplates whose basal planes are ±{111}PbS, which was previously theoretically predicted to have better surface ligand passivation. Subsequently, we found that the PbS nanoplates showed improved colloidal stability and did not suffer from severe aggregation despite numerous solvent wash steps. We further incorporated a film of nanoplates into a planar photodetector device with lateral Au electrodes. The amount of residual Cu2S in the PbS nanoplates, which can be tuned by adjusting the reaction time of the cation-exchange process, was found to play a crucial role in determining the in-plane conductivity of the film and therefore its photodetection efficiency. For PbS nanoplates with 7.8% residual Cu+, the responsivity and specific detectivity at 808 nm was ∼1739 A/W and ∼2.55 × 1011 Jones, respectively. The high responsivity was attributed to the very low PbS nanoplate film resistivity of 8.04 ohm·cm, which is comparable to commercial doped semiconductors.
Gene Detection in Complex Biological Media Using Semiconductor Nanorods within an Integrated Microfluidic Device
Bi X., Adriani G., Xu Y., Chakrabortty S., Pastorin G., Ho H.K., Ang W.H., Chan Y.
Article, Analytical Chemistry, 2015, DOI Link
View abstract ⏷
The salient optical properties of highly luminescent semiconductor nanocrystals render them ideal fluorophores for clinical diagnostics, therapeutics, and highly sensitive biochip applications. Microfluidic systems allow miniaturization and integration of multiple biochemical processes in a single device and do not require sophisticated diagnostic tools. Herein, we describe a microfluidic system that integrates RNA extraction, reverse transcription to cDNA, amplification and detection within one integrated device to detect histidine decarboxylase (HDC) gene directly from human white blood cells samples. When anisotropic semiconductor nanorods (NRs) were used as the fluorescent probes, the detection limit was found to be 0.4 ng of total RNA, which was much lower than that obtained using spherical quantum dots (QDs) or organic dyes. This was attributed to the large action cross-section of NRs and their high probability of target capture in a pull-down detection scheme. The combination of large scale integrated microfluidics with highly fluorescent semiconductor NRs may find widespread utility in point-of-care devices and multitarget diagnostics.
Observation of an Excitonic Quantum Coherence in CdSe Nanocrystals
Dong S., Trivedi D., Chakrabortty S., Kobayashi T., Chan Y., Prezhdo O.V., Loh Z.-H.
Article, Nano Letters, 2015, DOI Link
View abstract ⏷
Recent observations of excitonic coherences within photosynthetic complexes suggest that quantum coherences could enhance biological light harvesting efficiencies. Here, we employ optical pump-probe spectroscopy with few-femtosecond pulses to observe an excitonic quantum coherence in CdSe nanocrystals, a prototypical artificial light harvesting system. This coherence, which encodes the high-speed migration of charge over nanometer length scales, is also found to markedly alter the displacement amplitudes of phonons, signaling dynamics in the non-Born-Oppenheimer regime.
Dual wavelength electroluminescence from CdSe/CdS Tetrapods
Wong J.I., Mishra N., Xing G., Li M., Chakrabortty S., Sum T.C., Shi Y., Chan Y., Yang H.Y.
Article, ACS Nano, 2014, DOI Link
View abstract ⏷
We fabricated a single active layer quantum dot light-emitting diode device based on colloidal CdSe (core)/CdS (arm) tetrapod nanostructures capable of simultaneously producing room temperature electroluminesence (EL) peaks at two spectrally distinct wavelengths, namely, at ∼500 and ∼660 nm. This remarkable dual EL was found to originate from the CdS arms and CdSe core of the tetrapod architecture, which implies that the radiative recombination of injected charge carriers can independently take place at spatially distinct regions of the tetrapod. In contrast, control experiments employing CdSe-core-seeded CdS nanorods showed near-exclusive EL from the CdSe core. Time-resolved spectroscopy measurements on tetrapods revealed the presence of hole traps, which facilitated the localization and subsequent radiative recombination of excitons in the CdS arm regions, whereas excitonic recombination in nanorods took place predominantly within the vicinity of the CdSe core. These observations collectively highlight the role of morphology in the achievement of light emission from the different material components in heterostructured semiconductor nanoparticles, thus showing a way in developing a class of materials which are capable of exhibiting multiwavelength electroluminescence. © 2014 American Chemical Society.
Promoting 2D growth in colloidal transition metal sulfide semiconductor nanostructures via halide ions
Wu W.-Y., Chakrabortty S., Chang C.K.L., Guchhait A., Lin M., Chan Y.
Article, Chemistry of Materials, 2014, DOI Link
View abstract ⏷
Wet-chemically synthesized 2D transition metal sulfides (TMS) are promising materials for catalysis, batteries and optoelectronics, however a firm understanding on the chemical conditions which result in selective lateral growth has been lacking. In this work we demonstrate that Ni9S8, which is a less common nonstoichiometric form of nickel sulfide, can exhibit two-dimensional growth when halide ions are present in the reaction. We show that the introduction of halide ions reduced the rate of formation of the nickel thiolate precursor, thereby inhibiting nucleation events and slowing growth kinetics such that plate-like formation was favored. Structural characterization of the Ni9S8 nanoplates produced revealed that they were single-crystal with lateral dimensions in the range of ∼100-1000 nm and thicknesses as low as ∼4 nm (about 3 unit cells). Varying the concentration of halide ions present in the reaction allowed for the shape of the nanostructures to be continuously tuned from particle- to plate-like, thus offering a facile route to controlling their morphology. The synthetic methodology introduced was successfully extended to Cu2S despite its different growth mechanism into ultrathin plates. These findings collectively suggest the importance of halide mediated slow growth kinetics in the formation of nanoplates and may be relevant to a wide variety of TMS.
Self-assembled mononuclear palladium(II) based molecular loops
Sahoo H.S., Tripathy D., Chakrabortty S., Bhat S., Kumbhar A., Chand D.K.
Article, Inorganica Chimica Acta, 2013, DOI Link
View abstract ⏷
The meta-pyridine appended bidentate ligands L1, L2 and L3, crafted with flexible polyether spacer, are prepared by condensation of nicotinoyl chloride hydrochloride with di, tri-, and tetra-ethylene glycol, respectively. Self-assembled palladium(II) based mononuclear molecular loops of general formula cis-[Pd(N-N)(L)](NO 3)2 are obtained exclusively by combining 1 equiv. of a ligand L with 1 equiv. of a cis-protected palladium(II) component, cis-[Pd(N-N)(NO3)2]. Complexation of 2 equiv. of L with 1 equiv. of palladium(II) nitrate also resulted mononuclear complexes, i.e. [Pd(L)2](NO3)2. The ligands used in the complexation reactions are L1, L2 and L3 where as the cis-protecting units N-N employed are ethylenediamine (en), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen). Thus 12 number of mononuclear complexes are prepared using all possible combination of above mentioned three number of ligands and four variety of palladium(II) components. Large chelate rings are realized irrespective of the spacer length or type of palladium(II) component used. All the resulted compounds are characterized by NMR and ESI-MS techniques and the structure of cis-[Pd(en)(L1)] (NO3)2, cis-[Pd(bpy)(L1)](NO3) 2 and [Pd(L3)2](NO3)2 are confirmed by single crystal X-ray diffraction. The binding abilities of cis-[Pd(phen)(L1)](NO3)2, cis-[Pd(phen)(L 2)](NO3)2 and cis-[Pd(phen)(L 3)](NO3)2 with DNA has been investigated by ethidium bromide displacement assay and gel electrophoresis. © 2013 Elsevier B.V. All rights reserved.
Tunable giant multi-photon absorption using seeded CdSe/CdS nanorod heterostructures
Sum T.C., Xing G., Huan C.H.A., Chakrabortty S., Chan Y.
Conference paper, Optics InfoBase Conference Papers, 2012, DOI Link
View abstract ⏷
A clear strategy to enhance the MPA cross-sections whilst independently tuning the emissive wavelengths of semiconductor QDs using seeded CdSe/CdS nanorod heterostructures is presented. MPA cross-sections as large as 2-3 orders and two-photon pumped ASE with threshold fluence 1-2 orders smaller compared to CdSe/CdS QDs were achieved using these heterostructures. © OSA 2012.
Unusual selectivity of metal deposition on tapered semiconductor nanostructures
Mishra N., Lian J., Chakrabortty S., Lin M., Chan Y.
Article, Chemistry of Materials, 2012, DOI Link
View abstract ⏷
We describe a surfactant-driven method to synthesize highly monodisperse CdSe-seeded CdS nanoheterostructures with conelike, tapered geometries in order to examine the effects of shape on the location-specific deposition of Au under ambient conditions. Although preferential metal deposition at surface defect sites are generally expected, we found suprisingly that Au growth at the side facets of tapered linear and branched structures was significantly suppressed. Further investigation revealed this to be due to a highly efficient electrochemical Ostwald ripening process which was previously thought not to occur in branched nanostructures such as tetrapods. We exploited this phenomenon to fabricate uniform asymmetrically tipped CdSe-seeded CdS tetrapods with conelike arms, where a solitary large Au tip is found on one of the arms while the other three arms bear Ag 2S tips. Importantly, this work presents a synthetic route toward the selective deposition of metals onto branched semiconductor nanostructures whose arms have nearly symmetric reactivity. © 2012 American Chemical Society.
Tunable giant multi-photon absorption using seeded CdSe/CdS nanorod heterostructures
Sum T.C., Xing G., Huan C.H.A., Chakrabortty S., Chan Y.
Conference paper, 2012 Conference on Lasers and Electro-Optics, CLEO 2012, 2012,
View abstract ⏷
A clear strategy to enhance the MPA cross-sections whilst independently tuning the emissive wavelengths of semiconductor QDs using seeded CdSe/CdS nanorod heterostructures is presented. MPA cross-sections as large as 2-3 orders and two-photon pumped ASE with threshold fluence 1-2 orders smaller compared to CdSe/CdS QDs were achieved using these heterostructures. © 2012 OSA.
Ultralow-threshold two-photon pumped amplified spontaneous emission and lasing from seeded CdSe/CdS nanorod heterostructures
Xing G., Liao Y., Wu X., Chakrabortty S., Liu X., Yeow E.K.L., Chan Y., Sum T.C.
Article, ACS Nano, 2012, DOI Link
View abstract ⏷
Ultralow-threshold two-photon pumped amplified spontaneous emission (2ASE) and lasing in seeded CdSe/CdS nanodot/nanorod heterostructures is demonstrated for the first time. Such heterostructures allow the independent tunability of the two-photon absorption (2PA) cross-section (σ2) through varying the CdS rod size, and that of the emission wavelength through varying the CdSe dot size. With an enhanced σ2, 2ASE in these heterostructures is achieved with an ultralow threshold fluence of ∼1.5 mJ/cm2, which is as much as one order less than that required for spherical semiconductor NCs. Importantly, by exploiting this unique property of the seeded nanorods exhibiting strong quantum confinement even at relatively large rod sizes, a near reciprocal relation between the 2ASE threshold and the 2PA action cross-section (σ2η) (where η is the quantum yield) was found and validated over a wide volume range for II-VI semiconductor nanostructures. Ultrafast optical spectroscopy verified that while the Auger processes in these heterostructures are indeed suppressed, ASE in these samples could also be strongly affected by a fast hole-trapping process to the NR surface states. Lastly, to exemplify the potential of these seeded CdSe/CdS nanodot/nanorod heterostructures as a viable gain media for achieving two-photon lasing, a highly photostable microsphere laser with an ultralow pump threshold is showcased. © 2012 American Chemical Society.
Three-photon absorption in seeded CdSe/CdS nanorod heterostructures
Xing G., Chakrabortty S., Ngiam S.W., Chan Y., Sum T.C.
Article, Journal of Physical Chemistry C, 2011, DOI Link
View abstract ⏷
Size-dependent three-photon absorption (3PA) and three-photon-excited photoluminescence (PL) of CdSe/CdS nanorod heterostructures have been investigated using Z-scan and upconversion PL techniques with 150 fs laser pulses at 1300 nm. The PL from these rods shows clear cubic power dependence, and the 3PA cross section (σ3) was found to be as high as 1.5 × 10-75 cm6 s2 photon-2 for 39 nm long rods, which is 2-4 orders of magnitude larger than those previously reported for spherical semiconductor nanocrystals under ∼100 fs laser pulse excitation. Importantly, by exploiting the unique property of the seeded nanorods to exhibit strong quantum confinement even at relatively large rod sizes, a superlinear dependence of the 3PA cross section on nanoparticle volume was found and validated over a wide volume range. A simple derived relation that quantitatively describes σ3 and takes into account the laser pulse duration is proposed, thereby providing a clear basis of comparison between the σ3 values of various II-VI semiconductor nanomaterials and facilitating a more judicious choice of their use in 3PA applications. © 2011 American Chemical Society.
Engineering fluorescence in Au-tipped, CdSe-seeded CdS nanoheterostructures
Chakrabortty S., Xing G., Xu Y., Ngiam S.W., Mishra N., Sum T.C., Chan Y.
Article, Small, 2011, DOI Link
View abstract ⏷
Matchsticklike, Au-decorated, CdSe-seeded CdS nanorods are demonstrated as being able to retain a significant amount of their original fluorescence properties, exhibiting quantum yields of up to 23%. A proof-of-concept type application of these fluorescent metal-tipped semiconductor nanorods is given, exploiting the different chemical affinities of the metal and semiconductor moieties to facilitate directed assembly on a chemically patterned surface. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Tunable multi-photon absorption cross-sections using seeded CdSe/CdS nanorod heterostructures
Sum T.C., Xing G., Chou K.L., Huan C.H.A., Chakrabortty S., Chan Y.
Conference paper, Optics InfoBase Conference Papers, 2011,
View abstract ⏷
A clear strategy to enhance the MPA cross-sections whilst independently tuning the emissive wavelengths of semiconductor QDs using seeded CdSe/CdS nanorod heterostructures is presented. TPA cross-sections as large as 2-3 orders and two-photon pumped ASE with threshold fluence 1-2 orders smaller compared to CdSe/CdS QDs were achieved using these heterostructures. © 2011 OSA.
Tunable multi-photon absorption cross-sections using seeded CdSe/CdS nanorod heterostructures
Sum T.C., Xing G., Chou K.L., Huan C.H.A., Chakrabortty S., Chan Y.
Conference paper, IEEE Photonic Society 24th Annual Meeting, PHO 2011, 2011, DOI Link
View abstract ⏷
A clear strategy to enhance the MPA cross-sections whilst independently tuning the emissive wavelengths of semiconductor QDs using seeded CdSe/CdS nanorod heterostructures is presented. TPA cross-sections as large as 2-3 orders and two-photon pumped ASE with threshold fluence 1-2 orders smaller compared to CdSe/CdS QDs were achieved using these heterostructures. © 2011 IEEE.
PH-Responsive quantum dots via an albumin polymer surface coating
Wu Y., Chakrabortty S., Gropeanu R.A., Wilhelmi J., Xu Y., Er K.S., Kuan S.L., Koynov K., Chan Y., Weil T.
Article, Journal of the American Chemical Society, 2010, DOI Link
View abstract ⏷
Multifunctional peptide?polymer hybrid materials have been applied as efficient and biocompatible quantum-dot coating materials. Significant pH responsiveness (e.g., an influence of the pH on the quantum yields of the peptide?polymer/QDs) was found and is attributed to conformational rearrangements of the peptide backbone. © 2010 American Chemical Society.
Asymmetric dumbbells from selective deposition of metals on seeded Semiconductor nanorods
Chakrabortty S., Yang J.A., Tan Y.M., Mishra N., Chan Y.
Article, Angewandte Chemie - International Edition, 2010, DOI Link
View abstract ⏷
Sowing the seeds: The growth of Au and Ag2S nanoparticles at distinct positions on CdSe-seeded CdS heterostructured nanorods can be precisely controlled by variations in the concentration of the Au and Ag precursors, respectively. The ability to direct growth on the nanorods can lead to "Janus-type" structures where Au is located at the more reactive end of the nanorod, whilst Ag2S is located at the other (see picture; CdSe dark blue, CdS light blue, Au yellow, Ag2S gray). (Figure Presented) © 2010 Wiley-VCH Verlag GmbH S. Co. KGaA.
Enhanced tunability of the multiphoton absorption cross-section in seeded CdSe/CdS nanorod heterostructures
Xing G., Chakrabortty S., Chou K.L., Mishra N., Huan C.H.A., Chan Y., Sum T.C.
Article, Applied Physics Letters, 2010, DOI Link
View abstract ⏷
We present a method to separately tune the multiphoton absorption (MPA) and multiphoton excited photoluminescence using semiconductor core/enlarged-shell quantum dots (QDs), where the enlarged shell greatly enhances the MPA cross-sections while varying the core size facilitates emission wavelength selectivity. Following two-photon absorption (2PA) primarily in the shell and ultrafast charge-carrier localization to the core, luminescence occurs. We exemplify the validity of this method with CdSe/CdS nanorod heterostructures and find that the 2PA cross-section is enlarged to ∼1.4× 106 GM for 180 nm nanorods (with 800 nm, 150 fs laser pulse excitation) which is two to four orders larger than that of CdSe QDs. © 2010 American Institute of Physics.
