Satyajit Mondal

Role of curcumin on the determination of the critical micellar concentration by absorbance, fluorescence and fluorescence anisotropy techniques.

Curcumin (C(21)H(20)O(6)) is a natural antioxidant which has a wide range of physiological and pharmacological actions. Here, first time this is employed for the determination of the critical micellar concentration (cmc) of both ionic and nonionic surfactants using the measurements of UV absorption, fluorescence spectroscopy and fluorescence polarization anisotropy. Results on a number of surfactants have agreed with those evaluated from conductometric, tensiometric and calorimetric methods. The absorbance and fluorescence intensities of curcumin are enhanced by different micellar solutions. The profiles of the absorbance and fluorescence intensities as a function of concentration of surfactant can be described by sigmoidal function to evaluate the cmc of the studied amphiphiles. However, we have found that some of the anisotropy profiles are sigmoidal in nature.

Stability of curcumin in different solvent and solution media: UV-visible and steady-state fluorescence spectral study.

In aqueous solution, curcumin is photodegradable (light sensitive), it is also self-degradable in the dark. In basic medium, the second process is enhanced. The dark process has been studied in water and also in a number of protic and aprotic solvents, and aqueous solutions of ionic liquids, pluronics, reverse micelles and salt. The kinetics of the process followed the first order rate law; a comparative as well as individual assessment of which has been made. The kinetics of curcumin self-degradation has been found to be fairly dependent on salt (NaCl) concentration. Curcumin molecules in solution may remain in the enol or keto-enol form. From the visible spectral analysis, an estimate of the proportions of these forms in aqueous ethanol medium has been made. The temperature effect on the visible and fluorescence spectra of curcumin has been also studied. The steady state fluorescence anisotropy of the photoactive curcumin has been evaluated in different solvent and solution media. The reversibility of the steady state fluorescence anisotropy of curcumin on heating and cooling conditions has been examined. The results herein presented are new and ought to be useful as the study of physicochemistry of curcumin has been gaining importance in the light of its biological importance.

Interaction of cationic gemini surfactant tetramethylene-1,4-bis(dimethyltetradecylammonium bromide) with anionic polyelectrolyte sodium carboxymethyl cellulose, with two different molar masses, in aqueous and aquo-organic (isopropanol) media

A comparative study of the interactions of the cationic gemini surfactant tetramethylene-1,4-bis(dimethyltetradecylammonium bromide) (14-4-14) with anionic polymer sodium carboxymethylcellulose (NaCMC), with two different molar masses, was performed in water and isopropanol (IP)–water media. The interaction process was studied in detail using conductometry, tensiometry, turbidimetry and viscometry. At very low concentration, 14-4-14 monomers interact with the polymer. Above the critical aggregation concentration (cac), small micelle-like aggregates form complexes with the polymer. During the interaction process, coacervates are formed beyond Cs (polymer saturation concentration), which initially grow by aggregation and stay in the solution throughout the process. The interaction process is affected by addition of isopropanol into the medium. The intrinsic viscosities of the two NaCMCs were determined by using Huggins and Kraemer equations. Dynamic light scattering (DLS) study helps to determine the hydrodynamic size of the dispersed polymer and its surfactant-interacting complexes. The hydrodynamic size of the dispersed polymer and its interacting complex in IP–water media is lower than that obtained in aqueous solution. The surface morphology of the solvent removed polymer and its surfactant-interacting complex were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The pattern of the morphologies depends on the polymer–surfactant composition and the solvent environment.

Colloidal Dispersions of Lipids and Curcumin, and the Solubility and Degradation Kinetics of the Latter in Micellar Solution

A simple but potentially useful technique has been used to prepare colloidal dispersions of weakly soluble cholesterol(CS), Dipalmitoyl-Phosphocholine (DPPC), hexadecane dioic acid (HDA) and curcumin (CM) stabilized by the surfactants, SDS, NaC, CTAB, Tween-20, and NaDA at their critical micelle concentrations (CMC). The dispersions of DPPC were also vesicles (or liposomes); their nature, shape, and size were characterized and determined by flourimetry, dynamic light scattering (DLS), and field emission scanning electron microscopy (FESEM) methods. The solubility of CM in the micellar solution of concentrations, 1 to 10 CMC was also studied. The kinetics of degradation (instability) of the CM in basic medium in micellar solutions was investigated. The findings on the biologically important materials have been analyzed and presented.