Differential contribution of Igepal and CnTAB micelles on the photophysics of nonsteroidal drug Naproxen

Spectroscopic studies of Naproxen (NP), a nonsteroidal drug have been carried out in well characterized, micellar media of cationic surfactants of a homologous series having general formula CnTAB (alkyl trimethyl ammonium bromide) and of nonionic surfactants of Igepal (Ig) series (poly(oxyethylene) nonyl phenol). The fluorescence behavior of the drug molecule in CnTAB micelles has been found to be opposite to that in Igepal micelles. The binding constants during probe micelle binding have been evaluated from relevant fluorescence data. Location and nature of the surrounding medium of the probe in micellar media have been ascertained from fluorescence quenching study. Fluorescence anisotropy parameter has been monitored for exploring the imposed motional restriction of the microenvironment around the probe. Contrasting behavior of the drug molecule has been observed in two different types of micelles. Based on the experimental and theoretical studies, an attempt has been made to explain the different behavior of the probe in different media.

Effect of micelles of CnTAB and Igepals on the modulated photophysical properties of drug molecule NP, binding constant (Kb) and Stern–Volmer constant (Ksv).Figure optionsDownload as PowerPoint slideHighlights
► Naproxen exhibits different emission behavior in two types of micelles.
► Fluorescence quenching efficiency is greater in cationic micelles than nonionic micelles.
► Naproxen resides in two different regions in two types of micelles.
► Steady state anisotropy increases with the size of cationic micelles but reverse in nonionic micelles.