Showing papers by "Thalappil Pradeep published in 2015"

Antimicrobial silver: An unprecedented anion effect

Abstract: Silver is an indispensable metal but its use has to be minimised for sustainable growth Much of the silver lost during use is unrecoverable; an example being its use as an antimicrobial agent, a property known since ages While developing methods to create an affordable drinking water purifier especially for the developing world, we discovered that 50 parts per billion (ppb) of Ag+ released continuously from silver nanoparticles confined in nanoscale cages is enough to cause antimicrobial activity in conditions of normal water Here we show that the antibacterial and antiviral activities of Ag+ can be enhanced ~1,000 fold, selectively, in presence of carbonate ions whose concentration was maintained below the drinking water norms The protective layers of the organisms were affected during the carbonate-assisted antimicrobial activity It is estimated that ~1,300 tons of silver can be saved annually using this new way to enhance its antimicrobial activity

Rapid Synthesis of C-TiO2: Tuning the Shape from Spherical to Rice Grain Morphology for Visible Light Photocatalytic Application

Abstract: Visible light-active carbon-loaded anatase TiO2 (C-TiO2) nanocrystals of spherical, distorted spherical, rice grain and hexagonal morphologies, with a particle size range of 50–70 nm, have been synthesized by a rapid microwave-assisted route in the solution state. The morphology of these materials is greatly tuned at low concentrations of the precursors used. The absorption band gaps (Egap) are shifted to the visible region due to C loading, and the distorted spherical C-TiO2 exhibits a maximum energy shift relative to pure TiO2. Carbon gets deposited predominantly on the surface as graphitic carbon, in the preparative conditions, as confirmed by X-ray photoelectron, scanning electron microscopy elemental mapping and Raman spectroscopic studies. The rapid degradation of an endocrine disrupting agent and a persistent pollutant in wastewater, carbamazepine, by the rice grain shaped C-TiO2 is attributed to the large surface area (229 m2/g) of the particles and coexposure of the high surface energy and more r...

Zero Volt Paper Spray Ionization and Its Mechanism.

Abstract: The analytical performance and a suggested mechanism for zero volt paper spray using chromatography paper are presented. A spray is generated by the action of the pneumatic force of the mass spectrometer (MS) vacuum at the inlet. Positive and negative ion signals are observed, and comparisons are made with standard kV paper spray (PS) ionization and nanoelectrospray ionization (nESI). While the range of analytes to which zero volt PS is applicable is very similar to kV PS and nESI, differences in the mass spectra of mixtures are interpreted in terms of the more significant effects of analyte surface activity in the gentler zero volt experiment than in the other methods due to the significantly lower charge. The signal intensity of zero volt PS is also lower than in the other methods. A Monte Carlo simulation based on statistical fluctuation of positive and negative ions in solution has been implemented to explain the production of ions from initially uncharged droplets. Uncharged droplets first break up due to aerodynamics forces until they are in the 2-4 μm size range and then undergo Coulombic fission. A model involving statistical charge fluctuations in both phases predicts detection limits similar to those observed experimentally and explains the effects of binary mixture components on relative ionization efficiencies. The proposed mechanism may also play a role in ionization by other voltage-free methods.

Simultaneous Dehalogenation and Removal of Persistent Halocarbon Pesticides from Water Using Graphene Nanocomposites: A Case Study of Lindane

Abstract: This paper describes an unusual chemical reaction that takes place on a graphene composite in a concerted fashion. The reaction shows the conversion of a persistent organochlorine pesticide, lindane (C6H6Cl6), present in water, to different isomers of trichlorobenzenes (TCBs, C6H3Cl3) on the surface of reduced graphene oxide–silver composites (RGO@Ag). The reaction is unique to the composite and does not occur on RGO and nanoparticles of Ag separately. The products of the reaction were isolated and extensively characterized using analytical techniques such as gas chromatography–mass spectrometry, electrospray ionization mass spectrometry, infrared and NMR, which unequivocally confirmed their identity. The as-formed TCBs were removed from the aqueous medium by adsorption on the same composite. Adsorption of lindane is physical in nature, but that of TCBs is through π–π interactions. The study reveals the unusual chemical reactivity of graphene–metal composites and their potential for water treatment. The u...

A Unified Framework for Understanding the Structure and Modifications of Atomically Precise Monolayer Protected Gold Clusters

Abstract: Atomically precise monolayer protected clusters are molecules comprising a few-atom cluster core of a noble metal, typically Au or Ag, surrounded by a protective layer of ligands, exhibiting many special optical, electrical, catalytic, and magnetic properties, and are emerging as important materials in biology, medicine, catalysis, energy conversion and storage, and sensing. The structural diversity of these clusters or aspicules, as we definitively term them, meaning shielded molecules, combining the Greek word aspis (shield) with molecule, is rapidly increasing due to new compositions and modification routes such as ligand-exchange, alloying, or supramolecular functionalization. We present a structural analysis of the most stable cluster of this kind, Au25(SR)18, and propose a Borromean rings diagram for the cluster, showing its topological configuration of three interlocked (Au8S6)-rings. This simplified two-dimensional diagram is used to represent its structure and modifications via ligand or metal at...

Cellulose Derived Graphenic Fibers for Capacitive Desalination of Brackish Water.

Abstract: We describe a simple and inexpensive cellulose-derived and layer-by-layer stacked carbon fiber network electrode for capacitive deionization (CDI) of brackish water. The microstructure and chemical composition were characterized using spectroscopic and microscopic techniques; electrochemical/electrical performance was evaluated by cyclic voltammetry and 4-probe electrical conductivity and surface area by Brunauer–Emmett–Teller analysis, respectively. The desalination performance was investigated using a laboratory batch model CDI unit, under fixed applied voltage and varying salt concentrations. Electro-adsorption of NaCl on the graphite reinforced-cellulose (GrC) electrode reached equilibrium quickly (within 90 min) and the adsorbed salts were released swiftly (in 40 min) back into the solution, during reversal of applied potential. X-ray photoelectron spectroscopic studies clearly illustrate that sodium and chloride ions were physisorbed on the negative and positive electrodes, respectively during elect...

Percolation network dynamicity and sheet dynamics governed viscous behavior of poly-dispersed Graphene nano-sheet suspensions

Abstract: The viscosity of Graphene nano-sheet suspensions (GNS)and its behavior with temperature and concentration have been experimentally determined. A physical mechanism for the enhanced viscosity over the base fluids has been proposed for the poly-dispersed GNSs. Experimental data reveals that enhancement of viscosity for GNSs lie in between that of Carbon Nanotube Suspensions (CNTSs) and nano Alumina suspensions (nAS) , indicating the hybrid mechanism of percolation (like CNTs) and Brownian motion assisted sheet dynamics (like Alumina particles). Sheet dynamics and percolation, along with a proposed percolation Network Dynamicity Factor; have been used to determine a dimensionally consistent analytical model to accurately determine and explain the viscosity of poly-dispersed GNSs. It has been hypothesized that the dynamic sheets behave qualitatively analogous to gas molecules. The model also provides insight into the mechanisms of viscous behavior of different dilute nanoparticle suspensions. The model has been found to be in agreement with the GNS experimental data, and even for CNT and nano Alumina suspensions.

Efficient red luminescence from organic-soluble Au25 clusters by ligand structure modification

Abstract: An efficient method to enhance visible luminescence in a visibly non-luminescent organic-soluble 4-(tert butyl)benzyl mercaptan (SBB)-stabilized Au25 cluster has been developed. This method relies mainly on enhancing the surface charge density on the cluster by creating an additional shell of thiolate on the cluster surface, which enhances visible luminescence. The viability of this method has been demonstrated by imparting red luminescence to various ligand-protected quantum clusters (QCs), observable to the naked eye. The bright red luminescent material derived from Au25SBB18 clusters was characterized using UV-vis and luminescence spectroscopy, TEM, SEM/EDS, XPS, TG, ESI and MALDI mass spectrometry, which collectively proposed an uncommon molecular formula of Au29SBB24S, suggested to be due to different stapler motifs protecting the Au25 core. The critical role of temperature on the emergence of luminescence in QCs has been studied. The restoration of the surface ligand shell on the Au25 cluster and subsequent physicochemical modification to the cluster were probed by various mass spectral and spectroscopic techniques. Our results provide fundamental insights into the ligand characteristics determining luminescence in QCs.

Ambient solid-state mechano-chemical reactions between functionalized carbon nanotubes

Abstract: Carbon nanotubes can be chemically modified by attaching various functionalities to their surfaces, although harsh chemical treatments can lead to their break-up into graphene nanostructures. On the other hand, direct coupling between functionalities bound on individual nanotubes could lead to, as yet unexplored, spontaneous chemical reactions. Here we report an ambient mechano-chemical reaction between two varieties of nanotubes, carrying predominantly carboxyl and hydroxyl functionalities, respectively, facilitated by simple mechanical grinding of the reactants. The purely solid-state reaction between the chemically differentiated nanotube species produces condensation products and unzipping of nanotubes due to local energy release, as confirmed by spectroscopic measurements, thermal analysis and molecular dynamic simulations.

Noble metal clusters protected with mixed proteins exhibit intense photoluminescence

Abstract: In this paper is reported the synthesis and detailed mass spectrometric and spectroscopic characterization of highly luminescent Au and Ag clusters protected with mixed proteins. Taking advantage of the aggregation tendency of the protein, lysozyme (Lyz), an inter-protein conjugate was made from a physical mixture of two proteins, bovine serum albumin (BSA) and Lyz. Based on matrix-assisted laser desorption/ionization mass spectrometry data, the new cluster is assigned as ∼Au36@BSA–Lyz. This specific system showed a very high red luminescence and the calculated quantum yield was 42% which is the highest to date for such cluster systems. A similar study on an Ag system showed the formation of ∼Ag35@BSA–Lyz when a similar metal and protein concentration was used. By varying the concentration of the Ag precursor, different compositions of the cluster protected by the mixed protein were achieved. Such a system with a high quantum yield can be used for various applications such as sensors for ultralow levels of analytes, fluorescent tags and for tracking biomolecules in real systems.

A low cost approach to synthesize sand like AlOOH nanoarchitecture (SANA) and its application in defluoridation of water

Abstract: A B S T R A C T This paper describes a chitosan template assisted synthesis of nanocrystalline aluminium oxyhydroxide (g-AlOOH) at an ambient temperature (30 � 2 � C) and atmospheric pressure. High ability of the composite in removing fluoride from water has been demonstrated. The structural, morphological and compositional characteristics of the composite were studied using various spectroscopic and microscopic techniques. The results showed that the composite has nanoarchitecture comprising a number of g-AlOOH nanoparticles of size less than 10 nm attached to the fibrils of chitosan. Batch and continuous flow adsorption experiments were conducted to assess the parameters that influence the adsorption process. The parameters investigated include contact time, initial fluoride concentration, adsorbent dose, pH of the solution, co-existing ions in water, and size of the adsorbent granules. The composite showed good affinity to fluoride and the maximum uptake capacity was 13.47 (mg/g) (mg/L) � 1/n as described by Freundlich isotherm model. The kinetics of adsorption was affected by the size of the granules and the kinetic data followed pseudo-second-order rate equation. Except bicarbonate and sulfate, other competing ions studied did not affect the uptake of fluoride significantly. The high affinity to fluoride, simple and eco-friendly synthesis approach demonstrate the utility of the material for defluoridation of water.

Size Evolution of Protein-Protected Gold Clusters in Solution: A Combined SAXS–MS Investigation

Abstract: We report a combined small-angle X-ray scattering (SAXS) and mass spectrometric (MS) study of the growth of gold clusters within proteins, in the solution state. Two different proteins, namely, lysozyme (Lyz) and bovine serum albumin (BSA), were used for this study. SAXS study of clusters grown in Lyz shows the presence of a 0.8 nm gold core, which is in agreement with the Au10 cluster observed in MS. Dynamic light scattering suggests the size of the cluster core to be 1.2 nm. For BSA, however, a bigger core size was observed, comparable to the Au33 core obtained in MS. Concentration- and time-dependent data do not show much change in the core size in both SAXS and MS investigations. When metal–protein adducts were incubated for longer time in solution, nanoparticles were formed and protein size decreased, possibly due to the fragmentation of the latter during nanoparticle formation. The data are in agreement with dynamic light scattering studies. This work helps to directly visualize cluster growth withi...

Spatiotemporal mapping of three dimensional rotational dynamics of single ultrasmall gold nanorods.

Abstract: Spatiotemporal mapping of the position and orientation of nano-machinery inside complex and dynamic cellular environments is essential for the detailed understanding of many bio-physical processes. For the genuine observation of such biomolecular dynamics with high signal to noise ratio and reduced disturbance from the labeling probes, reduction in the size of nano-bio labels and simplification of techniques for their observation are important. Here we achieve this using polarized dark field scattering micro-spectroscopy (PDFSMS), in its simplest form so that it is deployable in several experiments. We not only locate tiny gold nanorods (GNRs) of size 30 (length) × 10 nm (diameter) inside HEK293 cells but also demonstrate mapping of their in-situ polarization patterns using a novel method. Real time observations of rotating GNR with DFSMS and PDFSMS are used to resolve in-plane and out-of-plane rotational modes of GNR. We have shown that PDFSMS itself can provide complete information about the state of GNR. A step ahead, we demonstrate the application of PDFSMS to track three dimensional rotational dynamics of transferrin-conjugated GNRs inside live HEK293 cells. These first-time observations of the three dimensional intracellular rotational dynamics of tiny GNRs using PDFSMS present a new landmark in single particle scattering spectroscopy.

Interaction of Acetonitrile with Water-Ice: An Infrared Spectroscopic Study

Abstract: Interaction of water-ice and acetonitrile has been studied at low temperatures in their codeposited mixtures, in ultrahigh vacuum conditions. They interact strongly at low temperatures (in the temperature range of 40–110 K), which was confirmed from the new features manifested in the reflection absorption infrared spectra of the mixtures. This interaction was attributed to strong hydrogen bonding which weakens upon warming as the acetonitrile molecules phase segregate from water-ice. Complete phase separation was observed at 130 K prior to desorption of acetonitrile from the water-ice matrix. Such a hydrogen-bonded structure is not observed when both the molecular solids are deposited as water on acetonitrile or acetonitrile on water overlayers. A quantitative analysis shows that in a 1:1 codeposited mixture, more than 50% acetonitrile molecules are hydrogen bonded with water-ice at low temperatures (40–110 K).

Aquananotechnology : global prospects

Abstract: Bimodal UV-Assisted Nano-TiO2 Catalyst - Crumb-Rubber Device for Treatment of Contaminated Water. Hierarchical Carbon and Hydrogels for Sensing, Remediation in Drinking Water, and Aquaculture Drug Delivery. Use of Nanomaterials in Water Remediation by Subcritical Water Process. Reduction of Priority Pollutants by Nanoscale Zerovalent Iron in Subsurface Environments. Nanotoxicity: Aquatic Organisms and Ecosystems. SonoPhotoCatalytic Cavitation (SPCC) in Water Treatment. Bilge and Ballast Water Treatment Using Nanotechnology. Nanoengineered Organosilica Materials for the Treatment of Produced Water. Arsenic Removal Metrics that Commercialized the Drinking Water Market. Commercialization of Nano from Water Sensors to Membranes. Nano-Photocatalytic Materials for Environmental Applications. Engineered Polymers and Organic-Inorganic Hybrids as Antimicrobial Materials for Water Disinfection. Key Water Treatment Technologies and Their Use by Several Industrial Segments and Future Potential for Nanotechnology. Iron-based Magnetic Nanomaterials in Wastewater Treatment. Sustainable Clean Water: Closing the Cycle. Thin Film Nanocomposite Reverse Osmosis Membranes. Technological Developments in Water Defluoridation. Nanotechnology Tunneling in the Environmental Kuznets Curve (EKC): Nano Zerovalent Iron for Underground Water Remediation. Engineered Nanomaterials for Groundwater Defluoridation. Advances in Nanostructured Polymers and Membranes for Removal of Heavy Metals in Water. Point-of-Drinking Water Purification Innovation: The Water Initiative. WaterHealth International: Decentralized Systems Provide Sustainable Drinking Water. Electrospun Nanofibers in Water Purification. Light Activated Nanotechnology for Drinking Water Purification. Modified TiO2-based Photocatalytic Systems for the Removal of Emerging Contaminants from Water. Noble Metal Nanosystems for Drinking Water Purification: from Nanoparticles to Clusters. Water Desalination: Emerging and Existing Technologies. Challenges and Opportunities for Nanotechnology in the Energy-Water Nexus. Nanotechnology in Passive Atmospheric Water Capture. Evaluation of a Zinc Clinoptilolite (ZZ(R)) for Drinking water Treatment. Phosphorous Removal and Recovery Using Nanotechnology. Nanomaterials Persuasive in Long History of Pursuing Perchlorates. Stormwater Runoff Treatment Using. Bioswales Augmented with Advanced Nanoengineered Materials. Graphene: Applications in Environmental Remediation and Sensing. A quantitative high-throughput assay for detection of biologically active endocrine-disrupting chemicals in water. Novel Carbon-based Nano-Adsorbents for Water Purification. Engineered Nanomaterials for Landfill Leachate Treatment in the Humid Tropics: the Sri Lankan Perspective. Al13-Cluster Nanoflocculants for Remediation of DOCs and Colloidal Particles in Water. GE Water Provides Nanotech Product Solutions.

Anisotropic Molecular Ionization at 1 V from Tellurium Nanowires (Te NWs).

Abstract: Ionization of molecular species from one-dimensional (1D) tellurium nanowires (Te NWs) has been achieved at 1 V. Molecules with a range of chemical functional groups gave quality mass spectra with high signal/noise ratios and no fragment ions. Experiments suggest the possibility of emission of microdroplets of solution due to the intense fields at the ends or interfaces of nanostructures. It appears that electrolytic conduction of the solution wetting of the nanostructures and not the electronic conduction of the nanostructures themselves is involved in the ionization event. Anisotropy was seen when two-dimensionally aligned Te NWs were used for ionization. The orientation effect of aligned Te NWs on molecular ion intensity is demonstrated for many analytes including organic molecules and amino acids with experiments done using a silicon substrate having aligned Te NWs. These measurements suggest the possibility of creating a MS source that extends the applicability of mass spectrometry. Analysis of a var...

Ambient preparation and reactions of gas phase silver cluster cations and anions

Abstract: Electrospray ionization of metal salt solutions followed by ambient heating transforms the resulting salt clusters into new species, primarily naked ionic metal clusters. The experiment is done by passing the clusters through a heated coiled loop outside the mass spectrometer which releases the counter-anion while generating the anionic or cationic naked metal cluster. The nature of the anion in the starting salt determines the type of metal cluster observed. For example, silver acetate upon heating generates only positive silver clusters, Agn+, but silver fluoride generates both positive and negative silver clusters, Agn+/− (3 < n < 20). Both unheated and heated metal salt sprays yield ions with characteristic geometric and electronic magic numbers. There is also a strong odd/even effect in the cationic and anionic silver clusters. Thermochemical control is suggested as the basis for favored formation of the observed clusters, with anhydride elimination occurring from the acetates and fluorine elimination from the fluorides to give cationic and anionic clusters, respectively. Data on the intermediates observed as the temperature is ramped support this. The naked metal clusters react with gaseous reagents in the open air, including methyl substituted pyridines, hydrocarbons, common organic solvents, ozone, ethylene, and propylene. Argentation of hydrocarbons, including saturated hydrocarbons, is shown to occur and serves as a useful analytical ionization method. The new cluster formation methodology allows investigation of ligand–metal binding including in reactions of industrial importance, such as olefin epoxidation. These reactions provide insight into the physicochemical properties of silver cluster anions and cations. The potential use of the ion source in ion soft landing is demonstrated by reproducing the mass spectra of salts heated in air using a custom surface science instrument.

In vitro colocalization of plasmonic nano-biolabels and biomolecules using plasmonic and Raman scattering microspectroscopy

Abstract: An insight into the intracellular fate of theranostics is important for improving their potential in biological applications. In vivo efficacy of plasmonic theranostics depends on our ability to monitor temporal changes in their size, shape, and state of aggregation, and the identification of molecules adsorbed on their surfaces. We develop a technique which combines plasmonic and Raman scattering microspectroscopy to colocalize plasmonic scattering from metallic nanoparticles with the Raman signatures of biomolecules adsorbed on the surface of the former. Using this technique, we have colocalized biomolecules with the plasmonic scattering from silver nanoparticles in the vicinity of Escherichia coli bacteria. To prove the applicability of this setup for the measurements on mammalian cells, imaging of HEK293 cells treated with gold nanoparticles was per- formed. We discuss the importance of such correlated measurements over individual techniques, although the latter may lead to misinterpretation of results. Finally, with the above-mentioned examples, we have given criteria to improve the specificity of theranostics. We believe that this methodology will be considered as a prime development in the assessment of theranostics. © 2015 Society of Photo-Optical Instrumentation Engineers

Identification of effective substrates for the direct analysis of lipids from cell lines using desorption electrospray ionization mass spectrometry

Abstract: RATIONALE: Various disease conditions, particularly tumours, can be understood easily by studying changes in the lipid profile of cells. While lipid profiles of tissues have been recorded by desorption electrospray ionization mass spectrometric (DESI-MS) imaging, there is paucity in standardized protocols for sample preparation involving cell cultures to generate reliable results. In this study, we report a method for the direct analysis of lipids from cultured cells by incorporating them onto Whatman 42 filter paper as a substrate for reliable DESI-MS analysis. METHODS: The WERI-RB1 cell line was spotted on commonly used substrates for DESI-MS analysis, such as glass slides, Teflon coated glass slides, thin layer chromatography (TLC) plates, and Whatman 42 filter paper. A comparison of mass spectrometric images with two different lipids was made to understand the behaviour of different surfaces when the same sample was spotted on them. Relative intensities of different lipid peaks in the WERI-RB1 cell line were compared and relative lipid abundances were also compared across two different human retinoblastoma cell lines; WERI-RB1 and Y79. RESULTS: The study demonstrates that good lipid signals can be obtained by DESI-MS when the cells are spotted on Whatman 42 filter paper. Tandem mass spectrometry was performed to identify the lipids as glycerophosphocholines (PC). Better lipid images from assembly of cells were obtained with distinct boundary when they were spotted on Whatman 42 filter paper than other surfaces. CONCLUSIONS: We demonstrate the use of a simple substrate for reliable DESI-MS analysis of cultured cells. This method has the potential to understand various interactions of cells with other external agents. The current method would help in the application of DESI-MS for biology in general and medical sciences in particular. Copyright © 2015 John Wiley & Sons, Ltd.

Rapid detection of Fusarium wilt in basil (Ocimum sp.) leaves by desorption electrospray ionization mass spectrometry (DESI MS) imaging

Abstract: Basil (Ocimum sp.), a medicinal herb is used fresh and/or dry in various (culinary, cosmetic and pharmaceutical) preparations. Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. basilici is limiting basil cultivation in many countries. Since the leaf is the edible part in basil, new approaches are required to identify, and to prevent the spread of Fusarium pathogens. Desorption electrospray ionization mass spectrometry (DESI MS) was used for imaging thin layer chromatography (TLC) – imprints of leaves of three different species of basil (Ocimum basilicum L., O. tenuiflorum L., and O. gratissimum L.), and the molecular manifestations during Fusarium contamination are recorded. DESI MS images showed the chemotaxonomic differences of basil species and the changes in metabolite ion peaks during pathogen infection. Besides easy detection of reported toxic metabolite(s) of the pathogen(s), the results include molecular images showing spatial distribution of all coexisting surface-bound metabolites in plant leaves, their fragment ions, and the transient changes in their spatial distribution during Fusarium attack under natural conditions. Demonstration of the same protocol to image seedling, young/mature leaves, basil/other related plant (Patchouli – Pogostemon cablin (Blanco) Benth.), wilt/other disease symptoms shows that prior knowledge of the metabolite profile of the plant/pathogen is not required. This rapid detection method can be tailored to large scale screening programs for plant diseases suggesting potential implications in agriculture and quarantine requirements.

Initial Growth Kinetics of Luminescent Quantum Clusters of Silver within Albumin Family Protein Templates

Abstract: We probed the initial growth kinetics of luminescent quantum clusters of silver (AgQCs) within two albumin family proteins, bovine serum albumin (BSA) and ovalbumin (Ova). Shorter time scale (seconds to minutes) growth of AgQCs monitored using real time photoluminescence spectroscopy has shown that, at lower concentrations of Ag+, only unstable QCs were formed. The major role of basic pH in the synthesis was not only to facilitate Ag+-BSA conjugation but also to provide well dispersed medium for controlled nucleation of QCs. Increase in the concentration of NaBH4 affects growth kinetics greatly and leads to increase in the growth rate of AgQCs; but for NaBH4 concentrations higher than the optimum value, growth rate becomes constant. Precise measurements have shown that excitation and emission of AgQCs exhibit linear red-shift with the increasing concentration of NaBH4 whereas protein excitation remains constant. Similar results were observed for both the proteins, Ova and BSA. We believe that various insi...