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Mandal, Asit Baran
- Physicochemical Properties of PEO-PPO-PEO Triblock Copolymer (Mol.Wt. 2000) Micelles in Sodium Dodecyl Sulfate (SDS) Micellar Environment
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Authors
Affiliations
1 Chemical Laboratory, Physical and Inorganic Chemistry Division, Central Leather Research Institute, Adyar, Chennai 600 020, IN
2 Department of Chemistry, Loyola College, Chennai 600 034, IN
1 Chemical Laboratory, Physical and Inorganic Chemistry Division, Central Leather Research Institute, Adyar, Chennai 600 020, IN
2 Department of Chemistry, Loyola College, Chennai 600 034, IN
Source
Journal of Surface Science and Technology, Vol 21, No 1-2 (2005), Pagination: 23-42Abstract
The hydration of the polymer micelles has been directly determined from the measurements of conductance of micellar solutions of the triblock copolymer (PEO-PPO-PEO) in 25 mM SDS (fixed) and in 5 mM NaCl (fixed), using the principle of the obstruction of electrolyte migration by the polymer. The asymmetry of the micellar entities of the polymer and the polymer-SDS mixed micellar systems and their average axial ratios are calculated using the intrinsic viscosity and hydration data obeying Simha-Einstein equation. The hydration of the polymer has also been determined by Einstein and Vand equations, and good agreement with the conductivity results obtained. Hydration number and micellar sizes are found to be variable with temperature. The aggregation number, ̅N of the polymer in an aqueous solution of SDS (25 mM, fixed) was determined by fluorescence spectroscopic technique considering the SDS solution as the solvent only in one case, and in the other case, the micellar concentration of SDS had been taken into account to consider the SDS-polymer mixed system. Both ̅N and the Stern-Volmer constant (Ksv) are variable with temperature. The shape of the polymer micelles has been observed to be ellipsoidal rather than spherical. From the absolute values of the axes, the micellar volume, hydrodynamic radius, radius of gyration, diffusional coefficients as well as translational (τD), rotational (τr) and effective (τa) correlation times have been calculated. The partial molal volume of the polymer micelles has also been determined and its comparison with the molar volume of the pure polymer suggested a volume contraction due to the immobilization of the water phase by the hydrophilic head groups of the polymer. The thermodynamic activation parameters for the viscous flow favour a more ordered water structure around the polymer micelles at higher temperatures.Keywords
Geometry of the Micelles, Triblock Copolymer, Mixed Micelles, Aggregation, Correlation Times and Thermodynamic Parameters.
- Kinetics of the Reaction of Cutch (Acacia catechu) with Sodium Sulphite in Tween-80 Micellar Environment
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Authors
Affiliations
1 Chemical and FT NMR Laboratory, Central Leather Research Institute, Adyar, Madras 600 020, IN
1 Chemical and FT NMR Laboratory, Central Leather Research Institute, Adyar, Madras 600 020, IN
Source
Journal of Surface Science and Technology, Vol 3, No 1 (1987), Pagination: 31-38Abstract
The rate constants and thermoydnamic activation parameters of the reactions of cutch tannins with Na2SO3 in the presence and absence of Tween-80 micelles were studied. Tween-80 micelles profoundly decelerated the reaction rate with the increase of temperature. High negative entropy of activation in presence of Tween-80 micelles suggest an overall organised transition state. The δ(ΔG*), the free energy difference between the reaction of cutch with Na2SO3 in aqueous environment and in Tween-80 micellar environment became less negative with increase of temperature from 60°C and became positive at 90°C presumably due to the instability of the micelles. The enthalpy entropy compensated each other. Microscopic measurements showed that the bigger size particles of cutch are formed in presence of Tween-80 micelles than in absence. Polvoxyethylated nonionic surfactant micelle is advantageous in solubilization of cutch tannins.Keywords
Thermodynamics, Transport Properties, Cutch, Tween-80, Micelles.- Interaction of Silver Nanoparticles with DNA Building Blocks
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Authors
Affiliations
1 Chemical Laboratory, Council of Scientific and Industrial Research (CSIR)–Central Leather Research Institute (CLRI), Chennai, 600 020, IN
1 Chemical Laboratory, Council of Scientific and Industrial Research (CSIR)–Central Leather Research Institute (CLRI), Chennai, 600 020, IN
Source
Journal of Surface Science and Technology, Vol 27, No 3-4 (2011), Pagination: 193-209Abstract
The interaction of DNA bases and corresponding nucleotides with silver nanoparticles (AgNPs) biofunctionalized by tryptophan, has been investigated by absorption spectroscopy and dynamic light scattering. Aggregation of AgNPs was observed in the presence of ATP and GTP, in contrast to nucleoside. This is due to change in pH of the medium in the presence of triphosphates. Aggregation due to ATP was found to be greater than that of GTP, which is due to the interaction between adeninium ion and tryptophanyl residue on the surface of nanoparticle. There is a direct relationship between ATP concentration and aggregation of AgNPs, which in future might assist in developing new protocols for sensing of adenine nucleotides.Keywords
Tryptophan, Adenine, ATP, Plasmon Resonance Absorption, Aggregation, Adsorption.- BSA can form Micelle in Aqueous Solution
Abstract Views :476 |
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Authors
Affiliations
1 Chemical Laboratory, Council of Scientific and Industrial Research (CSIR)–Central Leather Research Institute (CLRI),Chennai 600020, IN
1 Chemical Laboratory, Council of Scientific and Industrial Research (CSIR)–Central Leather Research Institute (CLRI),Chennai 600020, IN
Source
Journal of Surface Science and Technology, Vol 31, No 1-2 (2015), Pagination: 21-29Abstract
Protein aggregation is pathogenic and plays significant role in causing neurodegenerative diseases in biological system. Although the evolution of different types of protein aggregation mediated diseases are well-known, the origin and molecular mechanism of these aggregates remain unclear. In the present investigation, self-assembling characteristics of BSA is discussed by evaluating its critical micelle concentration (cmc) and aggregation number using surface tension and various spectroscopic techniques. The cmc of BSA is estimated to be 0.65-0.69 μM in solution. Steady state and time resolved fluorescence methods are employed to determine the aggregation number of the BSA micelles, which is found to be ~ 44. The accessibility of the fluorophore to the CPC quencher in the BSA micelle is assessed using Lehrer’s plot. Furthermore, the morphology and size of the aggregates are studied using HRTEM, Scanning Electron Microscopy, Confocal microscopy and Dynamic light scattering methods. The present study helps in understanding the physicochemical properties of BSA protein aggregation and also provides the mechanistic details of the phenomenon.Keywords
Aggregation, BSA, Lifetime, Micelle, Microscopy, SizeReferences
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