Aggregation behaviour of octyl-β-thioglucopyranoside in the presence of glycine

Micelle formation and structure of the non-ionic surfactant octyl-β-thioglucopyranoside (OTG) in aqueous solutions in the presence of different concentrations of glycine has been studied by using the fluorescence probe technique. By using the pyrene 1:3 ratio method it has been found that the addition of glycine produces a decrease in the critical micelle concentration of the surfactant. However, it seems that the presence of the additive does not modify the micellar size and shape in comparison with those observed in aqueous medium. In order to obtain information on the microstructural characteristics of the aggregates, the effect of glycine on the microenvironmental properties has been examined. The pyrene 1:3 ratio index and the intramolecular excimer formation of 1,3-bis-(1-pyrenyl)propane revealed that both micropolarity and microviscosity of micelles were practically unaffected with the presence of glycine in the medium. The most relevant conclusion that we can draw from this study is that glycine causes stabilization of the octyl-β-thioglucopyranoside micelles, acting through an indirect mechanism, but without affecting the general structure of the micelles.