49 results on '"Subhash Chandra Bhattacharya"'
Search Results
2. Spectroscopic and theoretical investigation of conformational changes of proteins by synthesized pyrimidine derivative and its sensitivity towards FRET application
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Dipti Singharoy, Swadesh Ghosh, and Subhash Chandra Bhattacharya
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Conformational change ,Protein Conformation ,Serum Albumin, Human ,010402 general chemistry ,01 natural sciences ,Analytical Chemistry ,Fluorescence Resonance Energy Transfer ,medicine ,Humans ,Bovine serum albumin ,Instrumentation ,Spectroscopy ,biology ,010405 organic chemistry ,Chemistry ,Serum Albumin, Bovine ,Models, Theoretical ,Human serum albumin ,Fluorescence ,Binding constant ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Transport protein ,Pyrimidines ,Spectrometry, Fluorescence ,Förster resonance energy transfer ,Docking (molecular) ,Biophysics ,biology.protein ,Protein Binding ,medicine.drug - Abstract
Interest in synthesizing and characterizing (IR, NMR and HRMS spectroscopic methods) a pyrimidine based Schiff-base ligand, 2-(2-(Anthracen-9-ylmethylene) hydrazinyl)-4,6-dimethyl pyrimidine (ANHP) has been developed for its application to ascertain the conformational change of protein and sensitivity towards fluorescence resonance energy transfer (FRET) process. Location of ANHP in bovine serum albumin (BSA) and human serum albumin (HSA) proteins environment has been determined using different spectroscopic techniques. Weakly fluorescent ANHP have shown greater protein induced fluorescence enhancement (PIFE) in case of HSA than BSA, though in both cases energy transfer efficiency are almost same but difference in binding constant values encourages us to find the location of ANHP within the complex protein environment. From the FRET parameter and α-helicity change, it has been found that ANHP bound with Trp-214 of HSA and surface Trp-134 of BSA. Conformational changes of proteins have been observed more for HSA than BSA in presence of ANHP, which has confirmed the location of ANHP in both the protein environments. Coupled with experimental studies, molecular docking analysis has also been done to explain the locations and distance dependent FRET process of ANHP in both proteins.
- Published
- 2018
3. Binding of ciprofloxacin to bovine serum albumin: Photophysical and thermodynamic aspects
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Subhash Chandra Bhattacharya, Nikhil Guchhait, and Bijan Kumar Paul
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0301 basic medicine ,030103 biophysics ,Circular dichroism ,Kinetics ,Biophysics ,Analytical chemistry ,Context (language use) ,Calorimetry ,010402 general chemistry ,01 natural sciences ,Protein Structure, Secondary ,03 medical and health sciences ,Ciprofloxacin ,Animals ,Radiology, Nuclear Medicine and imaging ,Bovine serum albumin ,Spectroscopy ,Protein secondary structure ,Radiation ,Radiological and Ultrasound Technology ,biology ,Chemistry ,Circular Dichroism ,Relaxation (NMR) ,Serum Albumin, Bovine ,Fluorescence ,0104 chemical sciences ,Spectrometry, Fluorescence ,biology.protein ,Thermodynamics ,Cattle ,Protein Binding - Abstract
The present work reveals the study of interaction of a promising chemotherapeutic drug ciprofloxacin (CFX) with a model transport protein bovine serum albumin (BSA). The occurrence of the drug-protein interaction is found to result in significant modulations of the fluorescence excitation and emission spectroscopic properties of CFX following interaction with BSA. However, the major focus of the study underlies a critical insight into the quantitation of the drug-protein interaction phenomenon. To this end, we have exploited the isothermal titration calorimetric (ITC) technique to quantify the affinity constant (K a ) and stoichiometry (n) of the CFX-BSA interaction with simultaneous revelation of the accompanying thermodynamics of the interaction process. In this context, our discussion also sheds light on the lacuna surrounding various experimental methodologies for evaluation of drug-protein binding parameters. Our endeavor also extends to elucidation of the kinetic parameters and energy of activation (E a ) of the CFX-BSA interaction. The present study also delineates the modulation of the dynamical aspects of CFX following interaction with BSA. The rotational relaxation dynamics of the protein-bound drug reveals the not-so-common “ dip-rise-dip ” anisotropy decay. Furthermore, the effect of drug binding on the native protein conformation has been evaluated from circular dichroism (CD) spectroscopy which reveals partial rupture of the protein secondary structure.
- Published
- 2017
4. A novel pyrazole based single molecular probe for multi-analyte (Zn2+ and Mg2+) detection in human gastric adenocarcinoma cells
- Author
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Subhash Chandra Bhattacharya, Abhishek Mukherjee, Anamika Dhara, Indrani Mukherjee, and Nikhil Guchhait
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inorganic chemicals ,Aqueous solution ,010405 organic chemistry ,General Chemical Engineering ,Metal ions in aqueous solution ,Analytical chemistry ,General Chemistry ,Carbohydrazide ,Pyrazole ,010402 general chemistry ,01 natural sciences ,Fluorescence ,Photoinduced electron transfer ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallography ,chemistry ,Selectivity ,Acetonitrile - Abstract
A new fluorescent sensor, 5-methyl-1H-pyrazole-3-carboxylic acid (6-methoxy-naphthalen-2-ylmethylene)-hydrazide (PYN), composed of a naphthalene group as the fluorogenic unit and a pyrazole carbohydrazide as the binding unit for metal ions has been designed and synthesized. The sensor shows excellent selectivity and sensitivity with a fluorescence enhancement towards Zn2+ and Mg2+ over other cations in aqueous acetonitrile solution. Turn-on fluorescent enhancements (FE) as high as ∼49 fold and ∼41 fold in mixed media for Zn2+ and, Mg2+ respectively were noticed. The signal enhancement of the sensor is based on chelation-enhanced fluorescence (CHEF) effect of PYN-Zn2+/Mg2+ with the inhibition of the photoinduced electron transfer (PET) effect. Moreover, the Job's plot established 1 : 1 stoichiometry of the complex formation between PYN and Zn2+ or Mg2+ ions. The limit of detection for Zn2+ and Mg2+ is as low as 2.2 × 10−7 M and 3.9 × 10−7 M respectively. PYN exhibited a second mode of selectivity for Zn2+ as it displaces Mg2+ from the PYN-Mg2+ complex. Density Functional Theory (DFT) calculations have been performed in order to show the structure and electronic properties of PYN and its complexes [PYN-Zn2+/Mg2+]. Cell imaging experiments confirmed that PYN can be used for monitoring intracellular Zn2+ and Mg2+ levels in living cells in vitro.
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- 2016
5. Correlation of FRET efficiency with conformational changes of proteins in ionic and nonionic surfactant environment
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Soumyadipta Rakshit, Sayantani Chall, Subhash Chandra Bhattacharya, Soumya Sundar Mati, and Dipti Singharoy
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Circular dichroism ,Aqueous solution ,Chemistry ,Analytical chemistry ,Ionic bonding ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Photochemistry ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Förster resonance energy transfer ,Protein structure ,Pulmonary surfactant ,Micellar solutions ,Materials Chemistry ,Denaturation (biochemistry) ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy - Abstract
We have studied the effect of interaction of surfactants on the FRET process in aqueous solution from transport proteins, BSA and HSA to the probe molecule, sodium salt of anthracene 1,5-disulphonate (1,5-AS). Cationic surfactant CTAB and gemini, anionic surfactant SDS and nonionic surfactant igepal-630 have been used for our investigation as surfactants and micellar solution. In organized media denaturation of protein occurs. Denaturation of protein has also been observed in presence of 1,5-AS. This has been established from steady state, time resolved fluorescence and circular dichroism (CD) studies in homogeneous and heterogeneous environments. Helecity calculations from CD spectra have also supported the results. Nonionic and ionic micellar solutions have been found to directly affect the protein helicity and the FRET parameters. The FRET parameters and denaturation of proteins in homogeneous and heterogeneous media have been compared.
- Published
- 2016
6. Aggregation-Induced Fabrication of Fluorescent Organic Nanorings: Selective Biosensing of Cysteine and Application to Molecular Logic Gate
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Subhash Chandra Bhattacharya, Sayantani Chall, and Soumya Sundar Mati
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Molecular logic gate ,Chemistry ,Analytical chemistry ,Infrared spectroscopy ,Nanoparticle ,Biosensing Techniques ,Surfaces and Interfaces ,Condensed Matter Physics ,Photochemistry ,Fluorescence ,Dynamic Light Scattering ,Naphthalimides ,Microscopy, Electron, Transmission ,Dynamic light scattering ,Transmission electron microscopy ,Electrochemistry ,Nanoparticles ,Molecule ,General Materials Science ,Cysteine ,Biosensor ,Spectroscopy - Abstract
Self-aggregation behavior in aqueous medium of four naphthalimide derivatives has exhibited substitution-dependent, unusual, aggregation induced emission enhancement (AIEE) phenomena. Absorption, emission, and time-resolved study initially indicated the formation of J-type fluorescent organic nanoaggregates (FONs). Simultaneous applications of infrared spectroscopy, theoretical studies, and dynamic light scattering (DLS) measurements explored the underlying mechanism of such substitution-selective aggregation of a chloro-naphthalimide organic molecule. Furthermore, transmission electron microscopy (TEM) visually confirmed the formation of ring like FONs with average size of 7.5-9.5 nm. Additionally, naphthalimide FONs also exhibited selective and specific cysteine amino acid sensing property. The specific behavior of NPCl aggregation toward amino acids was also employed as a molecular logic gate in information technology (IT).
- Published
- 2015
7. A colorimetric and turn-on fluorescent chemosensor for selective detection of Hg2+: theoretical studies and intracellular applications
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Soumyadipta Rakshit, Rimi Roy, Subhash Chandra Bhattacharya, and Sanjay Bhar
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Chemistry ,General Chemical Engineering ,Metal ions in aqueous solution ,Analytical chemistry ,chemistry.chemical_element ,General Chemistry ,Photochemistry ,Fluorescence ,Ion ,Mercury (element) ,Field emission microscopy ,Intramolecular force ,MTT assay ,Intracellular - Abstract
A new colorimetric, “turn-on” fluorescent chemosensor (DEAS-BPH) was synthesized for selective and sensitive recognition of Hg2+ ions with no interference from environmentally relevant metal ions in a mixed organo-aqueous medium. It was found that the presence of mercury induced nearly 27-fold fluorescence enhancement. This was attributed to the 1 : 2 metal–ligand complexation, ascertained by a Job's plot, NMR titration and HRMS studies. A theoretical study was conducted to rationalize the colorimetric sensing behaviour of the probe on the basis of an intramolecular charge transfer (ICT) mechanism. In addition, morphological alteration upon complexation with mercury was explored with the aid of Field Emission Scanning Electron Microscope (FESEM) measurement. Results of MTT assay and fluorescence microscopic studies unveiled that the probe is cell permeable with low cytotoxicity. Furthermore, the reversibility of the sensor and its efficacy to function in a wide range of pH values designated the suitability to image intracellular Hg2+ ions in living HepG2 and Escherichia coli bacterial cells.
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- 2015
8. Preferential Molecular Encapsulation of an ICT Fluorescence Probe in the Supramolecular Cage of Cucurbit[7]uril and β-Cyclodextrin: An Experimental and Theoretical Approach
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Subhash Chandra Bhattacharya, Anuva Samanta, and Nikhil Guchhait
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Bridged-Ring Compounds ,Models, Molecular ,chemistry.chemical_classification ,ONIOM ,Magnetic Resonance Spectroscopy ,Cyclodextrin ,beta-Cyclodextrins ,Imidazoles ,Supramolecular chemistry ,Analytical chemistry ,Water ,Quantum yield ,Nuclear magnetic resonance spectroscopy ,Molecular encapsulation ,Photochemistry ,Binding constant ,Acceptor ,Surfaces, Coatings and Films ,1-Naphthylamine ,Spectrometry, Fluorescence ,chemistry ,Nitriles ,Materials Chemistry ,Physical and Theoretical Chemistry ,Fluorescent Dyes - Abstract
Supramolecular interaction between an intramolecular charge transfer (ICT) probe, N,N-dimethylaminonaphthyl-(acrylo)-nitrile (DMANAN), and two well-recognized macrocyclic hosts, cucurbit[7]uril (CB7) and β-cyclodextrin (β-CD), has been studied in aqueous medium by absorption, emission, time-resolved measurements, and (1)H NMR spectroscopic methods. The changes in the profiles of the fluorescence spectra illustrate significant modifications in fluorescence intensity, decay time, and quantum yield upon confinement of probe within the hydrophobic cavity of the hosts. Using the Benesi-Hildebrand relationship, the stoichiometric ratio as well as the binding constant of the host-guest complexation has been estimated. The stable inclusion complexes of the probe with different hosts have been supported by DFT and ONIOM based quantum chemical calculations. These methods of measurement establish that the acceptor group of the probe resides inside the hydrophobic cavity of the macrocycle. The competitive binding of metal ions and cationic surfactants to CB7 has been excellently mapped with this guest fluorosensor.
- Published
- 2014
9. Photoinduced Electron Transfer Switching Mechanism of a Naphthalimide Derivative with its Solvatochromic Behaviour: An Experimental and Theoretical Study with In Cell Investigations
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Subhash Chandra Bhattacharya, Soumya Sundar Mati, Sourav Chowdhury, Krishnananda Chattopadhyay, Swadesh Ghosh, and Dipti Singharoy
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Metal ions in aqueous solution ,Analytical chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Catalysis ,Photoinduced electron transfer ,Metal ,chemistry.chemical_compound ,mental disorders ,Molecule ,010405 organic chemistry ,musculoskeletal, neural, and ocular physiology ,fungi ,Organic Chemistry ,Solvatochromism ,General Chemistry ,0104 chemical sciences ,Nap ,Solvent ,chemistry ,visual_art ,visual_art.visual_art_medium ,human activities ,psychological phenomena and processes ,Derivative (chemistry) - Abstract
The sole existence of a t-bone-shaped naphthalimide derivative [2-(2-aminoethyl)-1H-benzo[de]isoquinoline-1,3(2H)dione] (NAP), which gives rise to a photoinduced electron transfer (PET) mechanism, has been established using a combination of experimental and theoretical studies. In parallel an in vitro-in cell PET mechanism has also been shown. To understand the photophysics of NAP, solvent studies have been carried out in different solvents. In addition, theoretical calculations have been conducted to explain the spectroscopic properties through optimized structures. A "turn off" PET mechanism has also been observed in the presence of specific metal ions, namely, Cr3+ , Fe3+ and Hg2+ among a series of metal ions. Theoretical studies reveal that NAP-Cr3+ , NAP-Fe3+ and NAP-Hg2+ have their HOMO energy states lying in between a HOMO-LUMO energy state of the t-bone-type NAP molecule. On the contrary, the HOMO state of the other metal ion-NAP conjugate (NAP-Mn+ ) does not lie in between the HOMO-LUMO energy gap of the t-bone-type NAP molecule. Coupled with in vitro studies, in cell investigations reveal an enhancement of fluorescence intensity of NAP upon cytosolic metal sensing. Furthermore, a very high cell viability of NAP treated cells as tested by MTT assay and a fast permeation of the said compound as revealed by flow cytometry suggest NAP to be a potential candidate in metal sensing and bioimaging applications.
- Published
- 2017
10. Pyrimidine-based fluorescent zinc sensor: Photo-physical characteristics, quantum chemical interpretation and application in real samples
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Saugata Konar, Sayantani Chall, Soumya Sundar Mati, Subhash Chandra Bhattacharya, and Soumyadipta Rakshit
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Detection limit ,Pyrimidine ,Chemistry ,Metals and Alloys ,Analytical chemistry ,chemistry.chemical_element ,Zinc ,Condensed Matter Physics ,Fluorescence ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Metal ,chemistry.chemical_compound ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Molecule ,Titration ,Density functional theory ,Electrical and Electronic Engineering ,Instrumentation ,Nuclear chemistry - Abstract
For high-fidelity selective and sensitive fluorescent detection of zinc ions (Zn2+), a new pyrimidine based Schiff-base ligand PyMD (2,2′-((1Z, 1′Z)-(2,2′-(pyrimidine-2,4-diyl)bis(hydrazin-2-yl-1-ylidene))bis(ethan-1-yl-1-ylidene))diphenol) was designed and synthesized. In 4:1 methanol (MeOH)–water mixture, zinc (Zn2+) binding was found to promote ∼23 fold fluorescence enhancement of PyMD at wavelength 469 nm. The limit of detection (LOD) of Zn2+ was calculated to be 6.9 × 10−7 M according to fluorometric titration. The 1:1 binding mode of the metal complex was established by combined UV–vis, fluorescence, NMR and HRMS spectroscopic methods. Photophysical investigations including steady-state and time resolved analysis suggested a mechanism for the fluorescent zinc response that involved a ligand-to-metal charge transfer (LMCT) pathway. The experimental observations were further confirmed by DFT (Density Functional Theory) calculations of the free sensor molecule (i.e., PyMD) and the complex structure (PyMD-Zn2+). Finally, newly synthesized PyMD was applied for detection of free zinc in real samples, e.g., cabbage, banana, banana stem juice and commercial fruit juice. Besides, fluorescence behavior of PyMD-Zn2+ complex was also employed for Escherichia coli bacterial cell imaging study.
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- 2014
11. Photophysical aspects of biological photosensitizer Kynurenic acid from the perspective of experimental and quantum chemical study
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Subhash Chandra Bhattacharya, Nikhil Guchhait, and Anuva Samanta
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Models, Molecular ,Xanthurenates ,Photosensitizing Agents ,Ionic bonding ,Hydrogen-Ion Concentration ,Kynurenic Acid ,Photochemistry ,Tautomer ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,chemistry.chemical_compound ,Spectrometry, Fluorescence ,Kynurenic acid ,chemistry ,Excited state ,Hydroxyquinolines ,Quantum Theory ,Molecule ,Spectrophotometry, Ultraviolet ,Density functional theory ,Emission spectrum ,Ground state ,Instrumentation ,Spectroscopy - Abstract
In the present contribution, we have explored ground and excited state spectroscopic properties of an antiexcitotoxic and anticonvulsant drug, Kynurenic acid (KA), through steady-state absorption, emission and time-resolved emission spectroscopy and quantum chemical calculations. The main focus of this article is to illustrate the effects of various parameters such as the nature of the solvents and pH of the medium on the spectral properties of KA which confirms the presence of different neutral and ionic species in the ground and excited states. The molecule KA exists mainly as keto- or anionic form in the ground state, whereas the main contribution of its emission is arising from the keto tautomer in the excited state. Quantum chemical calculations by Density Functional Theory (DFT) method has been effectively employed to correlate the experimental findings. The ground and excited state properties of KA ascertained by means of experimental and theoretical method reveal that it resembles well with other two compounds, 4-hydroxyquinoline and xanthurenic acid formed by the decomposition of UV filters.
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- 2014
12. Micellization and related behavior of sodium dodecylsulfate in mixed binary solvent media of tetrahydrofuran (Tf) and formamide (Fa) with water: a detailed physicochemical investigation
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Subhash Chandra Bhattacharya, B. V. N. Phani Kumar, G. K. S. Prameela, Vinod K. Aswal, A. B. Mandal, Satya P. Moulik, Animesh Pan, and Bappaditya Naskar
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Formamide ,Chemistry ,Analytical chemistry ,Isothermal titration calorimetry ,General Chemistry ,Condensed Matter Physics ,Small-angle neutron scattering ,Micelle ,Krafft temperature ,Solvent ,chemistry.chemical_compound ,Critical micelle concentration ,Organic chemistry ,Tetrahydrofuran - Abstract
The detailed aggregation behavior of sodiumdodecyl sulfate (SDS) in tetrahydrofuran (Tf)-water (W) and formamide (Fa)-water (W) media at varied volume percent compositions has been investigated. Surface tension (ST), conductance (Cond), viscosity (Visc), isothermal titration calorimetry (ITC), nuclear magnetic resonance (NMR) and small angle neutron scattering (SANS) were used in this study. The presence of nonaqueous solvents affected the critical micelle concentration (CMC) of SDS, the counter-ion binding of the micelle, the energetics of the air/water interfacial adsorption and micellization of the amphiphiles in the bulk, the ion-association (ion-pair, triple-ion, quadruple, etc. between Na(+) and DS(-) ions) as well as the weakly soluble (aggregation less) amphiphile solution. Tf has been observed to produce a "dead zone" or "non-micelle formation zone" in the mixed Tf-W domain of 10-40 vol%. Fa influenced the SDS aggregation up to 70 vol%, at higher proportions (below the Krafft temperature (K(T))), instead of the micelle, "randomly arranged globular assembly" (RAGA) was formed. The correlation of the standard free energy of micellization (ΔG(m)(0)) with different solvent parameters (1) dielectric constant (ε), (2) viscosity (η0), (3) Reichardt parameter (E(T)(30)), (4) Gordon parameter (G), and (5) Hansen-Hildebrand hydrogen bonding parameter (δ(h)) has been attempted. It has been found that δ(h) produced a master correlation between ΔG(m)(0) and δ(h) for different binary mixtures such as Tf-W, Fa-W, Ml-W and Dn-W.
- Published
- 2014
13. Micellar charge induced emissive response of a bio-active 3-pyrazolyl-2-pyrazoline derivative: a spectroscopic and quantum chemical analysis
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Subhash Chandra Bhattacharya, Soumyadipta Rakshit, Arindam Sarkar, Sayantani Chall, Jorge Bañuelos, Iñigo López Arbeloa, Soumya Sundar Mati, and Dipti Singharoy
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Dynamic light scattering ,Chemistry ,General Chemical Engineering ,Excited state ,Analytical chemistry ,Physical chemistry ,Ionic bonding ,Molecular orbital ,General Chemistry ,Time-dependent density functional theory ,Time-resolved spectroscopy ,Micelle ,Effective nuclear charge - Abstract
The medium charge specific excited state behaviour of a bio-active and fluorescent 3-pyrazolyl-2-pyrazoline derivative (PYZ) was systematically monitored in aqueous solutions of ionic (CTAB, SDS) and non-ionic (Triton X-100) micelles, applying steady state and time resolved fluorescence spectroscopy in addition to theoretical molecular simulations. PYZ displays complementary emission characteristics according to the nature of the effective charge of the micelles which was rationalized on the very fundamental basis of the frontier molecular orbital approach as obtained from quantum chemical calculations involving Time Dependent Density Functional Theory (TD-DFT) in combination with B3LYP exchange correlation function using 6-31G(d,p) as the basis set. Dynamic Light Scattering (DLS) measurements provided crucial information regarding the fluorescence quenching pattern of micelle bound PYZ by quencher CpCl. This study essentially accentuates PYZ's photophysical response in different micellar media in conjunction with their individual mode of electrostatic interaction therein. The theoretically calculated HOMO–LUMO energy gap values provide adequate information about the emissive behaviour of PYZ in ionic micellar media. The variation in the lifetime values of PYZ in aqueous and micellar media act as added evidence of the fact that PYZ basically resides in different micro-environments as introduced by the respective micelles. Conclusively it was observed that, in the excited state, PYZ responded promptly and uniquely according to the nature of the micellar charge.
- Published
- 2014
14. Soft-Templated Room Temperature Fabrication of Nanoscale Lanthanum Phosphate: Synthesis, Photoluminescence, and Energy-Transfer Behavior
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Subhash Chandra Bhattacharya, Sayantani Chall, Soumya Sundar Mati, and Soumyadipta Rakshit
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Materials science ,Analytical chemistry ,chemistry.chemical_element ,Terbium ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Cerium ,General Energy ,Electron diffraction ,chemistry ,Chemical engineering ,Transmission electron microscopy ,Nanorod ,Physical and Theoretical Chemistry ,Selected area diffraction ,Fourier transform infrared spectroscopy ,High-resolution transmission electron microscopy - Abstract
We herein report a simple and effective soft template mediated synthesis protocol for the room temperature preparation of highly crystalline cerium (Ce3+) and terbium (Tb3+) doped lanthanum phosphate (LaPO4) nanorods (NRs) and nanoflowers. Anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-alkane soft template was chosen since it forms stable reverse micelles (RMs). Transmission electron microscopy (TEM) analysis corroborated successful formation of LaPO4:Ce3+,Tb3+ NRs having different aspect ratios (ranging from 2.8:1 to 7.6:1) under varying reaction conditions. The crystalline nature of the nanomaterials (NMs) was ascertained by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and small-area electron diffraction (SAED) studies. Energy-dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectroscopy further verified the elemental existence of the desirably synthesized nanostructures. Experimental results from thermogravimetric-differential therma...
- Published
- 2013
15. Effect of bovine serum albumin on the functionality and structure of catanionic surfactant at air–buffer interface
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Satya P. Moulik, Amiya Kumar Panda, Subhash Chandra Bhattacharya, and Kajari Maiti
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1,2-Dipalmitoylphosphatidylcholine ,Surface Properties ,Analytical chemistry ,Bioengineering ,Buffers ,Microscopy, Atomic Force ,Surface pressure ,Biomaterials ,Surface-Active Agents ,chemistry.chemical_compound ,Pulmonary surfactant ,Cations ,Desorption ,Monolayer ,Animals ,Bovine serum albumin ,Coacervate ,biology ,Chemistry ,Air ,technology, industry, and agriculture ,Serum Albumin, Bovine ,Hydrogen-Ion Concentration ,Solvent ,Kinetics ,Microscopy, Fluorescence ,Mechanics of Materials ,Dipalmitoylphosphatidylcholine ,biology.protein ,Cattle - Abstract
Interaction of bovine serum albumin (BSA) with the solvent spread monolayer of a catanionic surfactant, octadecyltrimethylammonium dodecylsulfate, (C18TA+DS−) at the air–buffer interface was investigated by measuring the surface pressure with time and change in surface area. Dipalmitoylphosphatidylcholine (DPPC) was used as reference. Kinetics of BSA desorption from the interface to the buffer subphase, that of C18TA+DS− and DPPC through their interaction with BSA, were also studied at different BSA concentrations (in the subphase) and surface pressures. Surface pressure (π)–area (A) isotherms (at pH = 5.4, μ = 0.01, T = 298 K) revealed that the coacervate/DPPC monolayer becomes expanded in the presence of BSA at low π while their protein bound species are released into the subphase at high π. Film morphology, studied by epifluorescence microscopy (EFM) and atomic force microscopy (AFM), reveals that the sizes of the domains of both DPPC and coacervate decrease in the presence of BSA. Presence of BSA in the coacervate and DPPC monolayer was supported from AFM data analysis.
- Published
- 2013
16. Influence of nanoscopic micellar confinements on spectroscopic probing and rotational dynamics of an antioxidative naphthalimide derivative
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Sayaree Dhar, Dipak Kumar Rana, and Subhash Chandra Bhattacharya
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chemistry.chemical_compound ,Colloid and Surface Chemistry ,Aqueous solution ,Fluorophore ,Chemistry ,Micellar solutions ,Cationic polymerization ,Analytical chemistry ,Surface charge ,Photochemistry ,Fluorescence ,Micelle ,Fluorescence anisotropy - Abstract
Entrapping of a fluorogenic material comprising prospective therapeutic activity in microhetrogeneous environments and modulating important photophysical properties is highly desirable as far as potential applications of such systems are concerned. The present work demonstrates the interesting photobehavior of a newly synthesized antioxidative naphthalimide (isoquinolinedione) derivative (ANAP) in micellar solutions of anionic sodium dodecyl sulphate (SDS), cationic cetyl trimethylammonium bromide (CTAB) and nonionic p-tert-octylphenoxy polyoxyethanol (TX-100) surfactants using steady-state, time-resolved fluorescence and fluorescence anisotropy techniques. The remarkable sensitivity of the fluorescence properties of ANAP to the polarity of the media is attributed to the existence of a fluorescent intramolecular charge transfer (ICT) state. ANAP is found to be an excellent fluorescence sensor for following the micellar aggregation process. Fluorometric studies suggest that the probe resides at the micelle–water interface in all these systems. The present effort endeavors the degree of accessibility of the fluorophore toward the metal ion quencher in the presence of micelles of different surface charge characteristics. The enhancements in the steady-state anisotropy and rotational relaxation time in the micellar media compared to that in pure aqueous solution reflect that the fluorophore resides in a motionally restricted environment introduced by the micelles.
- Published
- 2012
17. Fluorescence resonance energy transfer: A promising tool for investigation of the interaction between 1-anthracene sulphonate and serum albumins
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Subhash Chandra Bhattacharya, Paltu Banerjee, Arindam Sarkar, and Saptaparni Ghosh
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chemistry.chemical_classification ,Anthracene ,biology ,Biomolecule ,Biophysics ,Serum albumin ,Analytical chemistry ,Tryptophan ,General Chemistry ,Condensed Matter Physics ,Human serum albumin ,Biochemistry ,Fluorescence ,Atomic and Molecular Physics, and Optics ,chemistry.chemical_compound ,Förster resonance energy transfer ,chemistry ,biology.protein ,medicine ,Bovine serum albumin ,medicine.drug - Abstract
This present investigation has revealed that steady state as well as time-resolved fluorescence techniques can serve as highly sensitive monitors for exploring the interaction of fluorescent probe 1-anthracene sulphonate (1-AS) with model transport proteins, bovine serum albumin (BSA) and human serum albumin (HSA).We have focused on fluorescence resonance energy transfer (FRET) between excited tryptophan in transport proteins to 1-AS, for the study of relaxation dynamics of biological molecules.
- Published
- 2011
18. Size tunable synthesis and characterization of cerium tungstate nanoparticles via H2O/AOT/heptane microemulsion
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Subhash Chandra Bhattacharya and Smritimoy Pramanik
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Analytical chemistry ,chemistry.chemical_element ,Nanoparticle ,Condensed Matter Physics ,Cerium nitrate ,chemistry.chemical_compound ,Cerium ,Tungstate ,chemistry ,Dynamic light scattering ,General Materials Science ,Sodium tungstate ,Microemulsion ,Thermal stability - Abstract
Nanoparticles of cerium tungstate have been prepared in the nanodomain water pools of water/AOT [sodium bis(2-ethylhexyl)sulphosuccinate]/n-heptane, water in oil microemulsion at various [water]/[AOT] mole ratio (ω) by double displacement reaction of cerium nitrate with sodium tungstate adapting intermixing two microemulsions technique. The formation of cerium tungstate in the dispersion has been established by UV–vis, X-ray diffraction and Fourier transform infrared measurements. Thermal stability of the products has been determined by thermogravimetric/differential thermal analyzer. The hydrodynamic diameter of the nanoparticles formed at different ω has been determined by the dynamic light scattering method. The size and shape of the isolated particles have been examined by the transmission electron microscope. Size of the nanoparticles increases with increase in ω. The fluorescent property and the magnetic behaviour of the synthesized product have been observed. The nanoparticles do not undergo any chemical change in HCl medium but unstable in KOH.
- Published
- 2010
19. Physicochemical studies on the micellization behavior of cetylpyridinium chloride and triton X-100 binary mixtures in aqueous medium
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Subhash Chandra Bhattacharya, Debolina Mitra, Satya P. Moulik, Amiya Kumar Panda, and Suvasree Mukherjee
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chemistry.chemical_classification ,Chromatography ,Diffusion ,Analytical chemistry ,Surfaces and Interfaces ,Cetylpyridinium chloride ,Micelle ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Monomer ,chemistry ,Pulmonary surfactant ,Critical micelle concentration ,Triton X-100 ,Physical and Theoretical Chemistry ,Counterion - Abstract
Physicochemistry of micellization of binary mixtures of cetylpyridinium chloride (CPC) and Triton X-100 (TX-100) have been investigated and the data collected have been analyzed and correlated. Tensiometric, conductometric, spectrophotometric, calorimetric and polarographic methods have been employed in the study. Parameters like critical micellar concentration (CMC), counter-ion binding, energetics of micellization, interfacial surfactant adsorption and minimum area of amphiphile head groups at CMC have been determined. The diffusion coefficients of pure and mixed micelles in solution have been determined by the polarographic method. The regular solution theory of Rubingh has been considered to get information on the micellar composition and their mutual interaction (synergistic for the studied system) in solution. The packing of the monomer in micelle has been estimated to witness spherical geometry for CPC and its mixtures with TX-100, whereas the later has been found to be spheroidal. Polarographic measurements have evidenced comparable diffusion coefficients of CPC and TX-100 micelles whereas their mixed micelles have shown lower values with a minimum, at equimolar composition.
- Published
- 2009
20. Physicochemical characterization of reverse micelles of Triton X using 1-anthracene sulphonate as fluorescent probe: A spectroscopic study
- Author
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Sayaree Dhar, Subhash Chandra Bhattacharya, Somnath Ghosh, Dipak Kumar Rana, Tapas Kumar Mandal, and Arindam Sarkar
- Subjects
Anthracene ,Aqueous solution ,Aggregation number ,Thermodynamics of micellization ,technology, industry, and agriculture ,Analytical chemistry ,macromolecular substances ,Micelle ,Fluorescence ,Binding constant ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Critical micelle concentration - Abstract
The aggregation of surfactant of polyoxyethylene-p-(1,1,3,3-tetramethylbutyl)phenyl ether (Triton X) series in chloroform has been studied. The critical micellar concentration (cmc) of the reverse micelles formed has been determined by four different techniques. The determined cmc values by various techniques are close to each other and facilitate determination of the free energy change (Δ G ) values associated with the micellization. From the correlation of cmc with hydrophile–lipophile balance (HLB) it was found that cmc decreases with decrease in HLB values. The association constant of the reverse micelle with fluorescent probe 1-anthracene sulphonate (1-AS) and micellar aggregation number has been evaluated. The location of the fluorophore in the reverse micelle and the polarity of the micelle solubilized sites have been determined from the E T (30), Kosower Z , and dielectric constant values. The pH of the aqueous region of reverse micelles has been estimated by comparison method.
- Published
- 2009
21. Mechanistic Aspects of Quantum Dot Based Probing of Cu (II) Ions: Role of Dendrimer in Sensor Efficiency
- Author
-
Amiya Priyam, Subhash Chandra Bhattacharya, Srabanti Ghosh, and Abhijit Saha
- Subjects
Dendrimers ,Luminescence ,Photoluminescence ,Sociology and Political Science ,Surface Properties ,Clinical Biochemistry ,Analytical chemistry ,Nanoparticle ,Sulfides ,Ligands ,Photochemistry ,Biochemistry ,Ion ,Dendrimer ,Quantum Dots ,Cadmium Compounds ,Polyamines ,Particle Size ,Spectroscopy ,Fluorescent Dyes ,Ions ,Quenching ,Chemistry ,Clinical Psychology ,Quantum dot ,Tellurium ,Solvent effects ,Law ,Copper ,Social Sciences (miscellaneous) - Abstract
Selective quenching of luminescence of quantum dots (QDs) by Cu2+ ions vis-à-vis other physiologically relevant cations has been reexamined. In view of the contradiction regarding the mechanism, we have attempted to show why Cu2+ ions quench QD-luminescence by taking CdS and CdTe QDs with varying surface groups. A detailed study of the solvent effect and also size dependence on the observed luminescence has been carried out. For a 13% decrease in particle diameter (4.3 nm --3.7 nm), the quenching constant increased by a factor of 20. It is established that instead of surface ligands of QDs, conduction band potential of the core facilitates the photo-induced reduction of Cu (II) to Cu (I) thereby quenching the photoluminescence. Taking the advantage of biocompatibility of dendrimer and its high affinity towards Cu2+ ions, we have followed interaction of Cu2+-PAMAM and also dendrimer with the CdTe QDs. Nanomolar concentration of PAMAM dendrimer was found to quench the luminescence of CdTe QDs. In contrast, Cu2+-PAMAM enhanced the fluorescence of CdTe QDs and the effect has been attributed to the binding of Cu2+-PAMAM complex to the CdTe particle surface. The linear portion of the enhancement plot due to Cu2+-PAMAM can be used for determination of Cu2+ ions with detection limit of 70 nM.
- Published
- 2009
22. Role of hydrogen bonding on the spectroscopic properties of thiazolidinedione derivatives in homogeneous solvents
- Author
-
Sudin Bhattacharya, Sk. Ugir Hossain, Paltu Banerjee, Arindam Sarkar, and Subhash Chandra Bhattacharya
- Subjects
Molecular Structure ,Hydrogen bond ,Aryl ,Solvation ,Substituent ,Hydrogen Bonding ,Photochemistry ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,chemistry.chemical_compound ,Spectrometry, Fluorescence ,chemistry ,Excited state ,Solvents ,Moiety ,Thiazolidinediones ,Steady state (chemistry) ,Time-resolved spectroscopy ,Instrumentation ,Spectroscopy - Abstract
In this work, three newly synthesized derivatives of thiazolidinediones, with potential for application as drugs in pharmaceutical industry and free radical scavenging activity, have been taken up to investigate their behaviour in different homogeneous solvents. The purpose of this work is to study the solvation characteristics in ground and excited states of the derivatives by monitoring the absorbance and fluorescence band maxima. The steady state and time resolved fluorescence studies in protic and aprotic solvents have been rationalized on the basis of solute–solvent interaction and substituent effect on these photophysical processes have been analyzed. Substituents at different positions of the aryl moiety affect the hydrogen bond formation ability of the probes.
- Published
- 2009
23. High-energy C+ ion-irradiated low-density polyethylene (LDPE): Spectroscopic and morphological investigation
- Author
-
S. Vinodh Kumar, J.B.M. Krishna, Subhash Chandra Bhattacharya, A. Saha, and B. Ghadei
- Subjects
chemistry.chemical_compound ,Low-density polyethylene ,Radiation ,Materials science ,Ultraviolet visible spectroscopy ,chemistry ,Scanning electron microscope ,Analytical chemistry ,Irradiation ,Fourier transform infrared spectroscopy ,Polyethylene ,Absorption (chemistry) ,Ion - Abstract
The optical absorption spectra of 3.6 MeV 12 C ions irradiated low-density polyethylene (LDPE) show the gradual increase in the optical absorption and the shift from the near UV to the visible region with increase in ion fluence. The increase in absorption may be attributed to the generation of a conjugated system of bonds, which are also corroborated by FTIR. Scanning electron microscopic (SEM) studies reveal that the formation of linear network structure occurred at relatively lower ion fluence of 5×10 13 ions/cm 2 .
- Published
- 2009
24. Physicochemistry of Mixed Systems of Water/AOT (Surfactant)/Alkanol (Cosurfactant)/Cycloalkanone (Oil): A Detailed Study of Phase Behavior, Salt Effect, and Conductance Properties
- Author
-
Satya P. Moulik, Subhash Chandra Bhattacharya, Amiya Kumar Panda, and Mrinmoy De
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,Analytical chemistry ,Conductance ,Salt (chemistry) ,Cyclopentanone ,Cycloheptanone ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Mixed systems ,Pulmonary surfactant ,chemistry ,Phase (matter) ,Organic chemistry ,Physical and Theoretical Chemistry ,Turbidity - Abstract
Water in oil microemulsion (μE) systems comprising water/AOT ± alkanol (n-butanol to n-dodecanol)/cycloalkanone (cyclopentanone to cycloheptanone, CA5, CA6, and CA7) were physicochemically studied with respect to phase and conductance behaviors. In absence of alkanols, AOT produced large clear zone with the cycloalkanones, compared to linear alkanes. Clear zone was comprised of gel, viscous, and clear fluid. Alkanols increased the fluidity of μE while its clarity was reduced. A maximum two-phase region was observed for n-heptanol (also for formulations with n-octanol). Salts, which reduced the clarity of the μE, followed the order of effectivity: Na+
- Published
- 2009
25. Volatile interface of biological oxidant and luminescent CdTequantum dots: implications in nanodiagnostics
- Author
-
Abhijit Saha, Subhash Chandra Bhattacharya, and Amiya Priyam
- Subjects
Quenching ,Luminescence ,Photoluminescence ,Kinetics ,Analytical chemistry ,General Physics and Astronomy ,Cadmium telluride photovoltaics ,Absorption ,chemistry.chemical_compound ,chemistry ,Quantum dot ,Peroxynitrous Acid ,Quantum Dots ,Cysteine ,Particle Size ,Tellurium ,Physical and Theoretical Chemistry ,Absorption (chemistry) ,Oxidation-Reduction ,Peroxynitrite ,Cadmium - Abstract
In order to explore the feasibility of using quantum dots (QDs) as nanodiagnostic tools in cells under oxidative stress, the interaction of cysteine-functionalized CdTe QDs with peroxynitrite (PN), a powerful biological oxidant, was spectroscopically investigated. The photoluminescence (PL) of CdTe QDs was quenched to the extent of 85% at 86 microM concentration of peroxynitrite. In contrast, the loss of PL intensity was merely 7% for CdS QDs under identical conditions. The quenching pattern shows a positive deviation from Stern-Volmer equation, but obeys the Perrin equation for static quenching. The Perrin quenching constants increased with decreasing temperature. Size dependence was also prominently observed as quenching efficiency increased by 70% on moving from 4.0 nm sized CdTe QDs to 2.8 nm ones. Interestingly, the QDs exhibited a time-dependent auto-recovery of photoluminescence. At 25 and 15 degrees C, the recovery time was found to be 1.25 and 3.5 h, respectively, however, the extent of recovery remained nearly the same, about 22%. Peroxynitrite followed a first order decay kinetics with a half-life of 45.6 min, which got substantially reduced to 2.9 min in the presence of CdTe QDs. The over-all mechanism of the interaction has been explained as a two-pronged attack of peroxynitrite on (i) the cysteine-capping layer and (ii) the CdTe core, resulting in a reversible and irreversible loss of QD-photoluminescence.
- Published
- 2009
26. Spectroscopic investigation of 3-pyrazolyl 2-pyrazoline derivative in homogeneous solvents
- Author
-
Subhash Chandra Bhattacharya, Arindam Sarkar, Kumar K. Mahalanabis, Smritimoy Pramanik, Paltu Banerjee, and A. K. Mukherjee
- Subjects
Time Factors ,Polarity (physics) ,Hydrogen bond ,Relaxation (NMR) ,Solvatochromism ,Hydrogen Bonding ,Photochemistry ,Fluorescence ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,Solvent ,Kinetics ,chemistry.chemical_compound ,Spectrometry, Fluorescence ,Models, Chemical ,chemistry ,Spectrophotometry ,Excited state ,Solvents ,Pyrazoles ,Spectrophotometry, Ultraviolet ,Instrumentation ,Spectroscopy ,Derivative (chemistry) - Abstract
How solvent conditions such as solvent polarity and hydrogen-bonding affect the fluorescence of a newly synthesized 3-pyrazolyl 2-pyrazoline derivative (Pyz) having pharmaceutical activity has been explored. The solvatochromic effect of Pyz is due to a change in dipole moment of the compound in the excited state. The relaxation of S1 state is perturbed in hydrogen-bonding solvents. The fluorescence properties of the systems are strongly dependent on the polarity of the media. The non-radiative relaxation process is facilitated by an increase in the polarity of the media. The photophysical response of Pyz in different solvents has been explained considering solute-solvent interactions.
- Published
- 2008
27. Physicochemical Studies of Octadecyltrimethylammonium Bromide: A Critical Assessment of Its Solution Behavior with Reference to Formation of Micelle, and Microemulsion with n-Butanol and n-Heptane
- Author
-
Satya P. Moulik, Subhash Chandra Bhattacharya, Indranil Chakraborty, and Amiya K. Panda, and Kajari Maiti
- Subjects
Isothermal microcalorimetry ,Heptane ,Aqueous solution ,Conductometry ,Chemistry ,Analytical chemistry ,Micelle ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Pulmonary surfactant ,Materials Chemistry ,Organic chemistry ,Microemulsion ,Physical and Theoretical Chemistry ,Dispersion (chemistry) - Abstract
Octadecyl-trimethyl-ammonium bromide (C18TAB) is a much less studied representative in the alkyltrimethylammonium halide surfactant series. A comprehensive study of its normal and reverse micelle (microemulsion) formation has been herein conducted by the methods of conductometry, tensiometry, fluorimetry, and microcalorimetry. The energetics of its air/liquid interfacial adsorption and self-association in aqueous solution have been examined. The phase behavior of its combinations with water, n-butanol, and n-heptane in the formation of microemulsions have been investigated with identification of a variety of phases. The energetics of formation of water dispersion in oil (w/o) has been evaluated from dilution experiments conducted at different temperatures. From the results, structural parameters of the droplets have been determined at different [water]/[surfactant] mole ratios (omega) and temperatures. The w/o dispersions have evidenced both volume- and temperature-induced conductance percolation. The results have been treated in light of the Scaling equations, and the associated parameters for the process have been determined. The activation energies for the temperature-induced percolation process of the w/o dispersion have been evaluated and assessed.
- Published
- 2007
28. pH dependent interaction of biofunctionalized CdS nanoparticles with nucleobases and nucleotides: A fluorimetric study
- Author
-
Subhash Chandra Bhattacharya, Anindita Chatterjee, Amiya Priyam, and Abhijit Saha
- Subjects
chemistry.chemical_classification ,Photoluminescence ,Absorption spectroscopy ,Biophysics ,Analytical chemistry ,General Chemistry ,Condensed Matter Physics ,Photochemistry ,Biochemistry ,Fluorescence ,Atomic and Molecular Physics, and Optics ,Fluorescence spectroscopy ,Nucleobase ,chemistry ,Adenine nucleotide ,Nucleotide ,Luminescence - Abstract
The interaction of DNA bases and corresponding nucleotides with CdS nanoparticles (NPs), biofunctionalized by cysteine, has been investigated by absorption and fluorescence spectroscopy. Unique enhancement effect of adenine, in contrast to other nucleobases, on the luminescence of cysteine capped CdS (cys-CdS) NPs at both pH 7.5 and 10.5 was found, the extent of enhancement being much higher at pH 10.5. At the latter pH, the difference optical absorption spectra show development of new peak at 278 nm with corresponding decrease in the absorption of adenine at 260 nm, which is attributed to binding of adenine anion to the CdS surface through N7 of the purine ring. Appearance of a new band at 478 cm−1 and concomitant shift in the C8–N7 vibrations to 1610 cm−1 in the FTIR spectra of cys-CdS NPs with adenine also suggest Cd–N7 binding on the particle surface. Amongst various nucleotides, ATP exhibited maximum luminescence enhancement on CdS NPs for a given change in concentration in the micro-molar range at physiological pH. A quantitative correlation between ATP concentration and PL enhancement of CdS NPs has been established, a step which in future might assist in developing new protocols for fluorescence sensing of adenine nucleotides under certain pathological conditions.
- Published
- 2007
29. Surface-functionalized cadmium chalcogenide nanocrystals: A spectroscopic investigation of growth and photoluminescence
- Author
-
Subhash Chandra Bhattacharya, Anindita Chatterjee, Amiya Priyam, and Abhijit Saha
- Subjects
Photoluminescence ,Chemistry ,Inorganic chemistry ,Analytical chemistry ,Nucleation ,Quantum yield ,Crystal growth ,Condensed Matter Physics ,behavioral disciplines and activities ,Cadmium telluride photovoltaics ,Inorganic Chemistry ,Nanocrystal ,Ionic strength ,mental disorders ,Materials Chemistry ,Particle size - Abstract
The growth mechanism of CdTe nanocrystals (NCs) vis-a-vis CdS with stabilizing shell of cysteine has been examined. The nucleation and growth were found to be well separated for CdS NCs whereas there is partial overlap of the two events for CdTe NCs. The initial growth rate (d r /d t ) of CdS NCs was higher than that of CdTe NCs. As the reflux time was increased, the growth rate showed a linear decline with increasing particle size. Three distinct stages of growth were identified with respect to particle size distribution: focusing, defocusing and equilibrium. The extent of focusing for CdTe NCs (49%) was much larger than that of CdS NCs (23%). With increasing time of reflux, photoluminescence quantum efficiency (PLQE) rose initially and started decreasing after reaching a peak value. A maximum PLQE of 0.13 and 0.16 was observed for CdS and CdTe NCs, respectively, for the same size of 3.4 nm. The particle size increased with increasing concentration of the capping ligand, cysteine and maximum PLQE was obtained at an optimum molar ratio of Cd 2+ :cysteine. Interestingly, on increasing the ionic strength of the initial synthetic mixture, photoluminescence (PL) intensity of CdS NCs was substantially enhanced while the particle size remained unaffected.
- Published
- 2007
30. Interface of AOT/Brij mixed reverse micellar systems: Conductometric and spectrophotometric investigations
- Author
-
Subhash Chandra Bhattacharya, Rajib Kumar Mitra, Sujan Chatterjee, and Bidyut K. Paul
- Subjects
Fluorophore ,Analytical chemistry ,Conductance ,Conductivity ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Biomaterials ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Solubilization ,Percolation ,Molecule ,Large head - Abstract
Solubilization and conductivity studies are carried out with AOT/Brijs (Brij-30, Brij-35, Brij-52, Brij-56, Brij-58, Brij-72, Brij-76, Brij-78)/isooctane/water mixed reverse micellar systems. Replacement of AOT molecules with large head group Brij molecules (Brij-30, Brij-35, Brij-56, Brij-58, Brij-76, Brij-78) decreases the solubilization capacity, whereas those with smaller polar head groups (Brij-52 and Brij-72) increases it. The former blends assist the conductance percolation whereas the latter retard it. An attempt has been taken to obtain more insight on the interfacial composition of the mixed interface with the help of spectrophotometric studies using 7-hydroxycoumarin as the fluorophore. The results obtained from the solubilization and conductometric studies have been correlated with those obtained from the spectroscopic studies.
- Published
- 2006
31. Interface of AOT/Igepal CO720/cyclohexane/water mixed reverse micelle by spectroscopic approach
- Author
-
Susantamay Nandi, Sujan Chatterjee, and Subhash Chandra Bhattacharya
- Subjects
chemistry.chemical_compound ,Colloid and Surface Chemistry ,Quenching (fluorescence) ,chemistry ,Cyclohexane ,Pulmonary surfactant ,Excited state ,Analytical chemistry ,Polyethylene glycol ,Absorption (chemistry) ,Photochemistry ,Micelle ,Spectral line - Abstract
Visible spectra of Safranine T (ST) in anionic reverse micelle (AOT/cyclohexane/water), non-ionic reverse micelle (Igepal CO720/cyclohexane/water) and mixed reverse micelles of AOT/Igepal CO720/cyclohexane/water at different compositions and different ω (=[water]/[surfactant]) have been studied. Charge transfer band of Safranine T in reverse micellar and mixed reverse micellar medium has been isolated both in ground and excited state. Iodide ion induced dynamic quenching at low quencher concentration becomes a combination of both the dynamic and static quenching at high quencher concentration. Iodide ion induced quenching study has been used as a tool to identify the altered interface of AOT/Igepal CO720/cyclohexane/water mixed reverse micelle compared to AOT/cyclohexane/water reverse micelle. Absorption and fluorescence spectra of ST in polyethylene glycol coated interface of AOT reverse micelle has been observed to identify the role of poly(oxyethylene) group of Igepal CO720 on spectral behavior of ST in mixed reverse micelle.
- Published
- 2006
32. Distribution of quencher ions in ternary system of Igepal/water/carbon tetrachloride at different water pool concentration: A spectroscopic study
- Author
-
Susantamay Nandi, Sujit Kumar Ghosh, and Subhash Chandra Bhattacharya
- Subjects
chemistry.chemical_classification ,Ternary numeral system ,Quenching (fluorescence) ,Inorganic chemistry ,Iodide ,Analytical chemistry ,Micelle ,Chloride ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Bromide ,medicine ,Molecule ,Microemulsion ,medicine.drug - Abstract
A steady-state fluorescence quenching study has been undertaken to estimate aggregation numbers, N, and the average occupancy number ( n ¯ ) of quencher per micelle and the water pool size, rw, of nonionic surfactant Igepal (polyoxyethylene nonyl phenol), carbon tetrachloride and water reverse micelles at a different [water]/[Igepal] ratio. For the purpose, Safranine T (3,7-diamino-2,8-dimethyl-5-phenyl phenazinium chloride) has been employed as fluorescent probe and iodide, bromide and azide ions as static quencher. The fluorescence quenching data has been exploited to determine the nature and properties of water in the core of reverse micelles (RM), size of the water pool, association of quencher molecule with the RM, the localization of the probe and the distribution of quencher molecule in the quenching sphere. The demarcation of reverse micelles and microemulsion has also been determined.
- Published
- 2005
33. Spectroscopic studies of complexation of p-phenylenediamine with micelles and reverse micelles of Tweens
- Author
-
Subhash Chandra Bhattacharya and Sujan Chatterjee
- Subjects
Dipole ,Absorption band ,Chemistry ,Stability constants of complexes ,Electron affinity ,Analytical chemistry ,General Physics and Astronomy ,Physical chemistry ,Electron ,Physical and Theoretical Chemistry ,Resonance (chemistry) ,Micelle ,Acceptor - Abstract
The electron donor–acceptor (EDA) interactions were studied using p -phenylenediamine as donor and polyoxyethylene–sorbitan–monolaurate (Tween 20), polyoxyethylene–sorbitan–monopalmitate (Tween 40), polyoxyethylene–sorbitan–monostearate (Tween 60) and polyoxyethylene–sorbitan–monooleate (Tween 80) as acceptor in micellar and reverse micellar environments. A charge transfer (CT) absorption band was observed and the experimental CT transition energies are well correlated (through Mulliken’s equation) with the vertical electron affinity of the acceptors. Oscillator strengths, transition dipole moments, resonance energies and formation constants of the EDA complexes have been estimated. The experimental results were explained using a theoretical model in favour of electric dipole–dipole interaction between the donor and acceptor.
- Published
- 2005
34. Triplet state interaction of Safranine T with inorganic cations in different solvents
- Author
-
Pijus Kanti Khatua, Subhash Chandra Bera, Sujit Kumar Ghosh, and Subhash Chandra Bhattacharya
- Subjects
Quenching (fluorescence) ,Aqueous solution ,Chemistry ,Organic Chemistry ,Protonation ,Photochemistry ,Chloride ,Analytical Chemistry ,Inorganic Chemistry ,Solvent ,Absorbance ,Electron transfer ,medicine ,Triplet state ,Spectroscopy ,medicine.drug - Abstract
The triplet–triplet absorbance of Safranine T (3,7-Diamino-2,8-dimethyl-5-phenylphenaznium chloride) has been studied in a series of polar and non-polar solvents. When non-aqueous solvents are gradually added to the aqueous solution of Safranine T (ST) the lifetime of the triplet state decreases. It has been established that the dye forms weak complex with the solvent molecules. The quenching of triplet state of ST by Fe 2+ , Co 2+ and Mn 2+ has been studied in different solvents. The double protonated long-lived triplet species of ST; DH 2 + 2 3 absorbs at 580 nm. The decay of the triplets follows first order kinetics. The quencher generates reduced semidye from 3 ST by electron transfer mechanism. The reduction of 3 ST by Mn 2+ and Fe 2+ is thermodynamically allowed but electron transfer from Co 2+ to ST is endoergic. The mechanism of quenching by Co 2+ can be explained as compensation by charge transfer mechanism between 3 ST and Co 2+ .
- Published
- 2005
35. Partitioning of quencher ions in the micellar microenvironment of polyoxyethylene nonyl phenol
- Author
-
Subhash Chandra Bhattacharya, Pijus Kanti Khatua, Jayanta Kumar Ghosh, and Sujit Kumar Ghosh
- Subjects
Octoxynol ,Inorganic ions ,Photochemistry ,Micelle ,Fluorescence ,Polyethylene Glycols ,Analytical Chemistry ,Surface-Active Agents ,chemistry.chemical_compound ,Phenols ,Pulmonary surfactant ,Nickel ,Phenol ,Coloring Agents ,Instrumentation ,Micelles ,Spectroscopy ,Manganese ,Quenching (fluorescence) ,Chemistry ,Cobalt ,Atomic and Molecular Physics, and Optics ,Partition coefficient ,Spectrometry, Fluorescence ,Micellar solutions ,Phenazines ,Copper - Abstract
This paper has explored the quenching of fluorescence of the dye safranine T (ST) by the inorganic cations viz Cu2+, Co2+, Ni2+ and Mn2+ in micellar solutions of the surfactant dioxyethylene nonyl phenol (Igepal CO-210), pentaoxyethylene nonyl phenol (Igepal CO-520) and dodecaoxyethylene nonyl phenol (Igepal CO-720). The quenching results have been calculated in light of stern volmer equation (SV) to evaluate the extent of interaction between the fluorophore (ST) and quencher. The average concentration of the quencher ions in the micelle have been determined. The quenching efficiency of ST by inorganic ions in micellar medium is lower than that in aqueous medium. The results show that the ions get partitioned in the micellar medium. The values of the partition coefficient of the ions decrease with increase in HLB value and number of oxyethylene groups in Igepal.
- Published
- 2005
36. Physicochemical characteristics of reverse micelles of polyoxyethylene nonyl phenol in different organic solvents
- Author
-
Subhash Chandra Bhattacharya, Sujit Kumar Ghosh, and Pijus Kanti Khatua
- Subjects
Fluorenes ,Heptane ,Magnetic Resonance Spectroscopy ,Aggregation number ,Chloroform ,Chemical Phenomena ,Chemistry, Physical ,Surface Properties ,Chemistry ,Solvatochromism ,Analytical chemistry ,Micelle ,Binding constant ,Fluorescence spectroscopy ,Polyethylene Glycols ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Biomaterials ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Phenols ,Critical micelle concentration ,Solvents ,Thermodynamics ,Micelles - Abstract
The association of polyoxyethylene nonyl phenol (Igepal) in four different organic solvents such as chloroform, carbon tetrachloride, cyclohexane, and heptane has been studied. The critical micellar concentration of the reverse micelle (RM) formed in different nonaqueous media has been determined using four different techniques: UV-visible spectroscopy, fluorescence spectroscopy, Stokes shift, and NMR spectroscopic studies. From the correlation of cmc with hydrophile-lipophile balance (HLB), we have found that cmc decreases with decrease in HLB. The obtained cmc values using different methods have been found to be consistent and facilitate the determination of DeltaG values associated with the micellization. The association constant of the dye molecule Safranine T (ST) with the reverse micelle, aggregation number of the surfactant monomer, and location of fluorophore in the RM have been determined. The vertical ionization potential of Igepal, electron affinity of the dye, and the degree of charge transfer have been estimated by the theoretical AM1 calculations. A linear relationship has been obtained between cmc(s) and the ionization potential of the solvents. The polarity of the micelle solubilization sites has been determined from the solvatochromic shift, Kosower Z value, and ET(30) value.
- Published
- 2004
37. Quenching of fluorescence of 1-hydroxypyrene-3,6,8-trisulfonate (HPTS) by Cu2+, Co2+, Ni2+, I−, and cetylpyridinium (CP+) ions in water/AOT/heptane microemulsion
- Author
-
Subhash Chandra Bhattacharya, Soma Biswas, and Satya P. Moulik
- Subjects
Heptane ,1-hydroxypyrene ,Quenching (fluorescence) ,Analytical chemistry ,Cetylpyridinium ,Fluorescence ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Ion ,Biomaterials ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Microemulsion ,Action model - Abstract
The quenching of the fluorescence of HPTS (1-hydroxypyrene-3,6,8-trisulfonate) by Cu(2+), Ni(2+), Co(2+), I(-), and CP(+) (cetylpyridinium cation) has been studied in the w/o microemulsion medium formed with water, AOT [sodium salt of bis (2-ethylhexyl) sulfosuccinic acid], and heptane as components at two [H(2)O]/[AOT] ratios (omega), 6 and 20. The quenching process has been found to be dynamic in nature. The lifetimes of HPTS in the microemulsion medium in the absence and in the presence of quencher have been determined. The analysis of the results has been performed in terms of the Stern-Volmer equation and the quenching sphere of action model. The Poisson distribution equation has been also used in the analysis of the probability of quencher distribution in the microemulsion compartment. The quenching of HPTS has been found to be much lower in microemulsion than in bulk water.
- Published
- 2004
38. Fluorescence quenching of Safranine T by inorganic ions in reverse micelles of aerosol-OT in heptane
- Author
-
Subhash Chandra Bhattacharya and Susantamay Nandi
- Subjects
Heptane ,Aggregation number ,Quenching (fluorescence) ,Analytical chemistry ,Inorganic ions ,Condensed Matter Physics ,Photochemistry ,Micelle ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Aerosol ,chemistry.chemical_compound ,Pulmonary surfactant ,chemistry ,Safranine T ,Materials Chemistry ,Physical and Theoretical Chemistry ,Spectroscopy - Abstract
The fluorescence quenching of Safranine T (ST) by [Fe(CN)6]3−, [Fe(CN)6]4−, Fe2+, Co2+ and Cu2+ was studied in Aerosol orange T (AOT) reverse micelles in n-heptane. The quenching process was exploited to calculate the Stern Volmer quenching constants (KSV) using Stern Volmer equation, the aggregation number of AOT reverse micelles at different ω values. Upon progressive addition of water to ST/AOT/n-heptane solution, the quenching efficiency increases. The results are interpreted in terms of the variations in the microenvironments of ST which depend in a sensitive manner on the water / Surfactant (ω) molar ratio.
- Published
- 2000
39. The surfactant concentration-dependent behaviour of safranine T in Tween (20, 40, 60, 80) and Triton X-100 micellar media
- Author
-
Subhash Chandra Bhattacharya, Kamala Rani Acharya, and Satya P. Moulik
- Subjects
Aggregation number ,General Chemical Engineering ,technology, industry, and agriculture ,Analytical chemistry ,General Physics and Astronomy ,macromolecular substances ,General Chemistry ,Charge-transfer complex ,Micelle ,Solvent ,chemistry.chemical_compound ,chemistry ,Pulmonary surfactant ,Micellar liquid chromatography ,Triton X-100 ,Micellar solutions ,Organic chemistry ,lipids (amino acids, peptides, and proteins) - Abstract
The visible and fluorescence spectra of the dye safranine T were studied in micellar solutions of non-ionic surfactants in different concentration ranges. The complexing strengths (1 : 1 dye : micelle charge transfer complex formed between the dye and micelle) of the non-ionic micelles increase with increasing concentration of the surfactant in the micellar solution. The aggregation number and several solvent parameterss, i.e. the Kosower z value, intramolecular charge transfer energy E T 30 , dielectric constant of the micellar medium and viscosity of the micellar solution, were evaluated. These values remain constant over certain concentration ranges, but vary in different concentration regions of a surfactant.
- Published
- 1997
40. Facile room temperature synthesis of lanthanum oxalate nanorods and their interaction with antioxidative naphthalimide derivative
- Author
-
Smritimoy Pramanik, Abhijit Saha, Sayantani Chall, Subhash Chandra Bhattacharya, and Sayaree Dhar
- Subjects
Thermogravimetric analysis ,Materials science ,Dispersity ,Biomedical Engineering ,Analytical chemistry ,chemistry.chemical_element ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Acceptor ,Oxalate ,chemistry.chemical_compound ,chemistry ,Differential thermal analysis ,Lanthanum ,General Materials Science ,Nanorod ,Fourier transform infrared spectroscopy ,Nuclear chemistry - Abstract
UGC - DAE Consortium for Scientic Research, Kolkata Centre, 111/LB-8, Bidhanangar, Kolkata 700098, IndiaPolycrystalline lanthanum oxalate (LaOX) nanorods (NRs) were succesfully synthesized usingreverse micellar (RM) method. The study espouses the versatility of the reverse micellar methodforming monodisperse, stable nanorods at room temperature. The as-synthesized LaOX nanorodswere characterised by different techniques. Result shows that the nanorods of LaOX with aspectratio 10.2:1 have preferred growth direction of (020). The pure phase synthesis of the nanorods wasconrmed from fourier transformed infrared (FTIR) and X-ray diffraction (XRD) analysis. The thermogravimetric analysis (TGA) and differential thermal analysis (DTA) of the as-synthesized nanorodswere perfomed to observe their thermal degradation. Synthesized nanorods are uorescent hav-ing emission maximum at 329 nm. Fluorescence resonance energy transfer (FRET) phenomenonhas been observed between LaOX nanorods (energy donor) and naphthalimide (NAP) derivative(energy acceptor) and this mechanism can be helpful for sensing of NAP or NAP like moleculesused as antioxidative in living systems.
- Published
- 2012
41. Differential contribution of Igepal and CnTAB micelles on the photophysics of nonsteroidal drug Naproxen
- Author
-
Subhash Chandra Bhattacharya, Sayantani Chall, Soumya Sundar Mati, Tapas Kumar Mondal, and Sayaree Dhar
- Subjects
Naproxen ,Quenching (fluorescence) ,Chemistry ,Anti-Inflammatory Agents, Non-Steroidal ,Cationic polymerization ,Fluorescence Polarization ,Photochemistry ,Micelle ,Fluorescence ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,Polyethylene Glycols ,Homologous series ,chemistry.chemical_compound ,Surface-Active Agents ,Phenols ,medicine ,Organic chemistry ,Phenol ,Instrumentation ,Spectroscopy ,Fluorescence anisotropy ,Micelles ,medicine.drug - Abstract
Spectroscopic studies of Naproxen (NP), a nonsteroidal drug have been carried out in well characterized, micellar media of cationic surfactants of a homologous series having general formula CnTAB (alkyl trimethyl ammonium bromide) and of nonionic surfactants of Igepal (Ig) series (poly(oxyethylene) nonyl phenol). The fluorescence behavior of the drug molecule in CnTAB micelles has been found to be opposite to that in Igepal micelles. The binding constants during probe micelle binding have been evaluated from relevant fluorescence data. Location and nature of the surrounding medium of the probe in micellar media have been ascertained from fluorescence quenching study. Fluorescence anisotropy parameter has been monitored for exploring the imposed motional restriction of the microenvironment around the probe. Contrasting behavior of the drug molecule has been observed in two different types of micelles. Based on the experimental and theoretical studies, an attempt has been made to explain the different behavior of the probe in different media.
- Published
- 2011
42. Visible and fluorescence spectral studies on the interaction of safranine T with surfactant micelles
- Author
-
Subhash Chandra Bhattacharya, Satya P. Moulik, and Haritaran Das
- Subjects
Chromatography ,integumentary system ,General Chemical Engineering ,Enthalpy ,Analytical chemistry ,Fluorescence spectrometry ,General Physics and Astronomy ,General Chemistry ,equipment and supplies ,Micelle ,chemistry.chemical_compound ,Pulmonary surfactant ,chemistry ,Critical micelle concentration ,Micellar solutions ,Triton X-100 ,Equilibrium constant - Abstract
The visible spectra of safranine T in micellar solutions indicate 1:1 (dye to micelle) charge transfer complex formation with the non-ionic surfactants Triton X 100 (TX 100), Tween 20, Tween 40, Tween 60 and Tween 80 as well as with the anionic surfactant sodium dodecyl sulphate (SDS). The non-ionic surfactant micelles show stronger interaction than the ionic micelle SDS, the complexing strengths of the non-ionic micelles following the order Tween 80>Tween 60>TX 100>Tween 40>Tween 20. The fluorescence spectrum of the dye is also affected (intensified) by the surfactant micelles. The results confirm a 1:1 complex and comparable complexing strengths (except the position of TX 100) as revealed by the ground state spectra. Thermodynamic analysis shows that the increased stability of the dye—micelle complex is associated with a systematic increase in exothermic enthalpy and decrease in entropy which compensate each other. The equilibrium constants of the dye—micelle complex are directly proportional to the carbon numbers of the Tweens and inversely proportional to the critical micelle concentration (CMC) of the surfactants.
- Published
- 1993
43. Supersaturation driven tailoring of photoluminescence efficiency and size distribution: a simplified aqueous approach for producing high-quality, biocompatible quantum dots
- Author
-
Abhijit Saha, Subhash Chandra Bhattacharya, Soumen Ghosh, and Amiya Priyam
- Subjects
Supersaturation ,Aqueous solution ,Photoluminescence ,Luminescence ,Time Factors ,Chemistry ,Surface Properties ,Dispersity ,Analytical chemistry ,Nucleation ,Nanoparticle ,Water ,Biocompatible Materials ,Sulfides ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Colloid and Surface Chemistry ,Quantum dot ,Quantum Dots ,Cadmium Compounds ,Quantum efficiency ,Particle Size ,Tellurium - Abstract
Supersaturation was found to play a pivotal role during nanoparticle-synthesis and its subtle variation helped achieve two prime objectives: (a) high photoluminescence quantum efficiency (PLQE) and (b) narrow size distribution, thereby obviating the need for post-preparative treatments. Degree of supersaturation of initial synthetic mixture was varied by changing the concentration of reagents while keeping their molar ratio constant at 1:2.5:0.5 for [Cd2+]:[cysteine]:[chalcogenide]. An eight-fold increase in supersaturation caused a sharp focusing of size distribution by 64% for CdS quantum dots (QDs). The as-prepared CdS and CdTe QDs were found to have size distribution as low as 4% at higher supersaturation. For a four-fold increase in supersaturation, PLQE of as-prepared CdTe QDs (4.3 nm) rose by 5 times to a remarkably high value of 54%. The focusing of size distribution with increasing supersaturation was found to work well even in the absence of any stabilizer. A substantial overlap of nucleation and growth was found at low supersaturation ( 0.5 S CdTe ), whereas a good separation of the two events is achieved at a higher supersaturation ( 4 S CdTe ). This study provides a simplified aqueous route for producing highly monodisperse, photoluminescent and biocompatible nanoparticles.
- Published
- 2008
44. Physicochemical studies on goat pulmonary surfactant
- Author
-
Satya P. Moulik, Subhash Chandra Bhattacharya, Kajari Maiti, Kaushik Nag, Amiya Kumar Panda, Mauricia Fritzen-Garcia, and Suvasree Mukherjee
- Subjects
Surface Properties ,Electrospray ionization ,Biophysics ,Phospholipid ,Analytical chemistry ,Microscopy, Atomic Force ,Biochemistry ,Langmuir–Blodgett film ,chemistry.chemical_compound ,Pulmonary surfactant ,Phosphatidylcholine ,Monolayer ,Animals ,POPC ,Lung ,Phospholipids ,Goats ,Organic Chemistry ,technology, industry, and agriculture ,Proteins ,Pulmonary Surfactants ,Cholesterol ,chemistry ,Dipalmitoylphosphatidylcholine ,lipids (amino acids, peptides, and proteins) ,Aluminum Silicates - Abstract
The large aggregate (LA) fraction of goat pulmonary surfactant (GPS) was isolated and characterized. Goat lung surfactant extract (GLSE) was obtained by chloroform-methanol extraction of the saline suspended LA fraction. Total phospholipid (PL), cholesterol (CHOL), and protein were biochemically estimated. It was composed of approximately 83% (w/w) PL, approximately 0.6% (w/w) CHOL and approximately 16% (w/w) protein. CHOL content was found to be lower while the protein content was found to be higher than other mammalian pulmonary surfactants. Electrospray Ionization Mass Spectrometry (ESIMS) of GLSE confirmed dipalmitoylphosphatidylcholine (DPPC) as the major phospholipid species, with significant amounts of palmitoyl-oleoyl phosphatidylcholine (POPC), palmitoyl-myristoyl phosphatidylcholine (PMPC) and dioleoylphosphatidylcholine (DOPC). Functionality of the solvent spread GLSE film was carried out in a Langmuir surface balance by way of surface pressure (pi)-area (A) measurements. A high value of pi (approximately 65 mN m(-1)) could be attained with a lift-off area of approximately 1.2 nm(2) molecule(-1). A relatively large hysteresis was observed during compression-expansion cycles. Monolayer deposits at different pi, transferred onto freshly cleaved mica by Langmuir-Blodgett (LB) technique, were imaged by atomic force microscopy. DPPC-enriched domains (evident from height analyses) showed dimensions of 2.5 microm and underwent changes in shapes after 30 mN m(-1). Functionality and structure of the surfactant films were proposed to be controlled by the relative abundances of protein and cholesterol.
- Published
- 2007
45. Spectroscopic studies of 2-(2-bromo-ethyl)-6-nitro-benzo[de]isoquinolene-1,3-dione in water/alkanol mixed solvents and nonionic micelle of Igepal CO series
- Author
-
Subhash Chandra Bhattacharya, Sk Ugir Hossain, Smritimoy Pramanik, Sudin Bhattacharya, Sujan Chatterjee, and Paltu Banerjee
- Subjects
Quinolones ,Medicinal chemistry ,Micelle ,Analytical Chemistry ,Polyethylene Glycols ,Propanol ,chemistry.chemical_compound ,Organic chemistry ,Acetonitrile ,Instrumentation ,Spectroscopy ,Tetrahydrofuran ,Micelles ,Temperature ,Water ,Nitro Compounds ,Atomic and Molecular Physics, and Optics ,Solvent ,Kinetics ,chemistry ,Alcohols ,Solvents ,Spectrophotometry, Ultraviolet ,Solvent effects ,Ethylene glycol ,Protic solvent - Abstract
Spectroscopic studies of newly synthesized bioactive compound 2-(2-bromo-ethyl)-6-nitro-benzo[de]isoquinolene-1,3-dione (BNBIO) have been carried out in polar aprotic solvent, viz. acetonitrile, tetrahydrofuran, 1,4-dioxan, ethylene glycol, dimethyl formamide, and polar protic solvent, viz. methanol, ethanol, propanol, water. Variation in absorbance of BNBIO in water–methanol, water–ethanol and water–propanol mixtures at their different compositions have been observed. Absorption behaviour of the dye has been studied in poly(oxyethylene) nonylphenol surfactants Igepal CO 630, Igepal CO 720 and Igepal CO 890 containing same hydrophobic tail and different numbers of poly(oxyethylene) groups. Experimental results of the BNBIO nonionic micelles have been explained in terms of 1:1 electron donor–acceptor (EDA) complexation and the complexation equilibrium becomes suppressed with increasing number of poly(oxyethylene) residue on the Igepal surfactant. Variation in binding constant of dye–micelle complexation has been rationalized considering a competitive equilibrium process between the BNBIO–water interactions.
- Published
- 2006
46. Spectroscopic studies of interaction of Safranine T with nonionic micelles and mixed micelles
- Author
-
Sujan Chatterjee and Subhash Chandra Bhattacharya
- Subjects
Spectrophotometry, Infrared ,Chemistry ,Analytical chemistry ,Flory–Huggins solution theory ,Acceptor ,Micelle ,Atomic and Molecular Physics, and Optics ,Fluorescence ,Analytical Chemistry ,Solvent ,Surface-Active Agents ,Pulmonary surfactant ,Critical micelle concentration ,Intramolecular force ,Phenazines ,Ionization energy ,Instrumentation ,Spectroscopy ,Micelles - Abstract
The visible spectra of Safranine T (ST) in micellar solution of Brij 58, Tween 20 and Tween 40 and mixed micellar solution of Brij 58/Tween 20 and Brij 58/Tween 40 indicate formation of 1:1 charge transfer (CT) complex between acceptor ST and donor nonionic micelles and mixed micelles. The experimental CT transition energies are well correlated (through Mulliken's equation) with the vertical ionization potential of the donors. The solvent parameters, i.e. the intramolecular charge transfer energy ET(30) have been determined from the Stokes spectral shift. Variations of ionization potential and micropolarity in the mixed micellar region have been investigated as a function of surfactant composition and the obtained results in mixed micellar medium has been compared to the normal micelles. The critical micelle concentration (CMC) values determined at various surfactant compositions are lower than the ideal values indicating a synergistic interaction. The interaction parameter (β) and micellar stability has been calculated using regular solution theory.
- Published
- 2005
47. An efficient, Schiff-base derivative for selective fluorescence sensing of Zn2+ions: quantum chemical calculation appended by real sample application and cell imaging study
- Author
-
Saugata Konar, Sayantani Chall, Soumya Sundar Mati, Subhash Chandra Bhattacharya, and Dipti Singharoy
- Subjects
Schiff base ,Ligand ,Organic Chemistry ,Inorganic chemistry ,Analytical chemistry ,Quantum yield ,Biochemistry ,Fluorescence ,chemistry.chemical_compound ,chemistry ,Mass spectrum ,Proton NMR ,Molecule ,Density functional theory ,Physical and Theoretical Chemistry - Abstract
Since zinc ions (Zn2+) are involved in numerous biological phenomena and go through subsequent interactions with zinc-binding proteins, we have attempted a sensitive fluorescence based detection of this second most abundant metal ion using an engineered and synthesized Schiff-base ligand, namely 2,4-bis((Z)-2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)pyrimidine (PyHP). The ligand exhibits a zinc-induced fluorescence response when investigated in a MeOH–buffer (10 mM HEPES, pH = 7) (4 : 1) solvent mixture. The presence of zinc ions (λex = 410 nm, quantum yield, ϕ = 0.20) causes approximately 45 fold fluorescence enhancement at 489 nm. Formation of the metal–ligand complex was ascertained by 1H NMR and mass spectra analysis. 1 : 1 binding affinity was ascertained according to Job's plot. Apart from this, theoretical interpretation of the experimental outcome was also obtained by applying density functional theory (DFT) to the PyHP-Zn2+ complex formation. The practical applicability of the ligand has been tested in bacterial cells as well as in mammalian cell imaging and also by measuring and comparing the amount of Zn2+ in some real samples such as liquid milk, tomato juice, banana stem juice and commercial fruit juice.
- Published
- 2014
48. Single step aqueous synthesis of pure rare earth nanoparticles in biocompatible polymer matrices
- Author
-
Subhash Chandra Bhattacharya, Sayantani Chall, Aparna Datta, Abhijit Saha, and Sampad Kumar Biswas
- Subjects
Materials science ,Aqueous solution ,Dispersity ,Analytical chemistry ,Nanoparticle ,chemistry.chemical_element ,General Chemistry ,Polyvinyl alcohol ,chemistry.chemical_compound ,Dynamic light scattering ,chemistry ,Materials Chemistry ,Fourier transform infrared spectroscopy ,Cyclic voltammetry ,Europium ,Nuclear chemistry - Abstract
The room temperature synthesis of water soluble, stable rare earth (RE) metal nanoparticles (MNPs) with controlled size is a long standing interest. In the present work, we have established a synthetic strategy for the preparation of pure europium (Eu0) metal nanoparticles (NPs) in aqueous solution employing a γ-radiolytic reduction technique. Since radiolysis is the cleanest method amongst all other chemical routes, we preferentially choose this technique for the reduction of precursor Eu3+ ions to nanoscale metals in our work. This has been possible as hydrated electrons (e−aq) having a very high reduction potential (E0(H2O/e−aq) = −2.87 VNHE) produced in situ can efficiently reduce Eu3+ to Eu0. Synthesized Eu0 MNPs were stabilised within the matrices of biocompatible polymers, polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP). Reduction of the metal ion has been conducted at different irradiation doses with a maximum dose of 83.88 kGy. The irradiated solution shows an absorption maximum at 266 ± 2 nm and an emission maximum at 394 ± 5 nm. Analysis of transmission electron microscopy (TEM) images shows that the average sizes of PVA and PVP encapsulated Eu0 NPs are 13 ± 0.6 nm and 17 ± 1.01 nm, respectively ([Eu3+] = 5.0 × 10−3 mol dm−3, [polymer] = 1.0%). Formation of monodisperse pure Eu0 MNPs was further characterised by dynamic light scattering (DLS), energy dispersive X-ray (EDX) as well as Fourier transformed infrared (FTIR) spectroscopy and cyclic voltammetry (CV) studies.
- Published
- 2012
49. Temperature dependence of quenching of fluorescence of anthracene sulphonates by small inorganic anions
- Author
-
Subhash Chandra Bhattacharya and K.K. Rohatgi-Mukherjee
- Subjects
Anthracene ,Quenching (fluorescence) ,Stereochemistry ,General Chemical Engineering ,Analytical chemistry ,General Physics and Astronomy ,Entropy of activation ,General Chemistry ,Redox ,Electron transfer ,chemistry.chemical_compound ,Reaction rate constant ,chemistry ,Ionic strength ,Azide - Abstract
The fluorescence quenching of water-soluble and amphiphilic anthracene sulphonates (monosulphonates and disulphonates) by I − , N 3 − , Br − and Cl − was studied. The rate constants for quenching depend on the ionic strength of the solution, and at μ = 0 they are observed to be a function of the redox potentials of the quenchers, except for the azide iron. The free energy Δ G ° of the quenching reaction was calculated for anthracene-1-sulphonate and anthracene-1,5-disulphonate from the redox potentials of the fluorescers and quenchers. A linear correlation is observed in the endoergic region of Δ G ° (for Br − and Cl − , including I − in the exoergic region, suggesting an electron transfer mechanism. The slope is only about 2 eV −1 , compared with the ideal value of 17 eV −1 . From the temperature dependence of the quenching the thermodynamic parameters Δ H ≠ , Δ S ≠ and Δ G ≠ were evaluated for I − , N 3 − and Br − , and the results indicate that the entropy of activation Δ S ≠ plays a definite role. N 3 − does not follow an isokinetic plot.
- Published
- 1988
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