Effect of spacer length of alkanediyl-α,ω-bis(dimethylcetylammonium bromide) gemini homologues on the interfacial and physicochemical properties of BSA

The interactions of bovine serum albumin (BSA) with cationic gemini surfactants alkanediyl-alpha,omega-bis(dimethylcetylammonium bromide) (designated as C16CsC16Br2, s = 4, 5, and 6) and single chain surfactant cetyltrimethylammonium bromide (CTAB) have been investigated with tensiometry, Rayleigh's scattering, fluorescence spectroscopy, and circular dichroism at physiological pH and 25 degrees C. The results of the multi-technique approach showed that the gemini surfactants interact more efficiently with the proteins than their conventional single chain counterparts and their efficiency increases with decrease in the length of the spacer. The saturation in interfacial tension occurred at a lower concentration in presence of BSA compared to CMC of the surfactants in absence of BSA and the concentration of gemini surfactants corresponding to interfacial saturation decreases with decrease in the spacer length. Fluorescence and circular dichroism spectroscopy results revealed increase in unfolding of BSA with decrease in spacer length of gemini surfactants. (C) 2010 Elsevier By. All rights reserved.