Conductivity and fluorescence studies on the micellization properties of sodium cholate and sodium deoxycholate in aqueous medium at different temperatures: Effect of selected amino acids

• Micellization of (NaC/NaDC + amino acid) system has been investigated by conductivity and fluorescence probe studies.
• Leucine has advanced the micellization predominantly among all amino acids.
• Both types of hydrations have governed the temperature dependence of CMCCMC values.
• Micellization of NaDC is found to be more entropy controlled than that of NaC.
• (Enthalpy + entropy) compensation phenomenon has been observed.

In order to add to the existing knowledge of aqueous solution behavior of bile salts in presence of amino acids, the micellization properties of sodium cholate (NaC) (1 to 20) mmol · kg−1, and sodium deoxycholate (NaDC) (0.5 to 10) mmol · kg−1 in 0.1 mol · kg−1 aqueous solution of glycine, leucine, methionine, and histidine have been investigated at different temperatures (293.15 to 318.15) K at intervals of T = 5 K by using conductivity and fluorescence probe studies. The critical micelle concentration (CMC) values have been determined and elucidated in terms of hydrophobicity as well as hydrophilicity of NaC and NaDC in aqueous solution of these additives. Thermodynamic parameters of micellization viz. standard Gibbs free energy (ΔmicGo), standard enthalpy (ΔmicHo), and standard entropy (ΔmicSo) have also been calculated to extract information regarding the nature of micellization of bile salts in aqueous solutions. The (enthalpy + entropy) compensation plots have been interpreted to the contribution of chemical part towards micellization or stability of the micelle formed.

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