Interaction of Indole-3-Propionic Acid (IPA) and Surfactant Micelles: A Fluorescence Study

The study of interaction of indole-3-propionic acid (IPA) a biologically and analytically important molecule, with the micelles of non-ionic and ionic surfactants. IPA is a plant growth hormone in the auxin family and is an ingredient in many commercial horticulture plant rooting product. The studies have been conducted by fluorescence spectral technique at room temperature. IPA shows fluorescence excitation peak at 285 nm and emission peak at 370 nm. The non-ionic surfactants decreased the fluorescence intensity of IPA. The ionic surfactants enhanced the fluorescence intensity except CPC. Except few, all the surfactants caused a blue shift of 15 nm in the emission peak position. These spectral observations were supplemented by parallel absorption studies and some theoretically calculated spectral parameters. The fluorescence properties as well as the theoretically calculated spectral data have been used to characterize the heteroenvironments of the micelles in terms of their polarity, probe solubilization site and critical micelle concentration. This paper briefly discusses the importance of surfactants and biological system model as well as the use of micelles in pharmacy as an important tool that finds numerous applications.