Influence of lactose on the micellar behaviour and surface activity of bile salts as revealed through fluorescence and surface tension studies at varying temperatures

In this paper, an attempt has been made to explore some information about the effect of disaccharide (lactose) on the micellization mechanism of bile salts namely sodium cholate (NaC) and sodium deoxycholate (NaDC) by applying surface tension and fluorescence probe techniques for ternary (water + lactose + NaC/NaDC) system. The critical micelle (aggregation) concentration (CM(A)C) values for NaC (4 to 22 mmol.dm(-3)) and sodium NaDC (1 to 10 mmol.dm(-3)) in aqueous solutions of lactose (0.0, 0.5,1.0, and 15) % w/v in the temperature range 293.15 to 313.15 K at an interval of 5 K, has been determined from both the studies. Fluorescence probe study has also been applied in order to determine CM(A)C for the studied system, which endorses the results drawn from surface tension studies. Different interfacial and thermodynamic parameters derived from surface tension (gamma) values and their variations have been explained in terms of modification in surface activity and micellar behaviour of these bile salts. The CM(A)C values determined from these measurements are found to be in excellent agreement with each other. (C) 2016 Elsevier B.V. All rights reserved.