Preservative solubilization induces microstructural change of Triton X-100 micelles

Abstract

The interaction of preservatives which are extensively used in food, pharmaceutical and personal care products, such as p-hydroxy benzoic acid esters (parabens) and gallic acid ester for instance propyl gallate has been investigated with commonly used non-ionic surfactant p-tert-octylphenoxy polyethylene (9.5) ether, Triton X-100 (TX-100). Solubilization of these preservatives alters the micellar behaviour of TX-100 elucidated by cloud point (CP), viscometry, dynamic light scattering (DLS), small angle neutron scattering (SANS) and NOESY measurement techniques. The changes in size/shape of TX-100 micelles depend on the hydrophilic and hydrophobic interactions with preservatives. These types of interaction facilitate the site of solubilization of preservatives in TX-100 micelles. Micellar growth of TX-100 was more pronounced for parabens as their alkyl ester chain length increases. Moreover, the micellar growth was more prominent for propyl paraben (PP) as compared to more polar propyl gallate (PG). The salt induced changes in the interaction between preservatives and TX-100 micelles have also been determined.