Solubilization of quercetin in P123 micelles: Scattering and NMR studies

Abstract

This study reveals the mechanistic aspects drug solubilization in Pluronic P123 (P123) micelles using NMR techniques, such as Diffusion-Ordered NMR Spectroscopy (DOSY), NMR relaxation time and quantitative NMR (qNMR). Quercetin was used as a model hydrophobic drug. The effect of shell-crosslinking upon drug-micelle interaction and drug release has also been studied. Average hydrodynamic size of micelles was found to be 22 nm. The size did not change appreciably even following shell-crosslinking and quercetin solubilization. The diffusion coefficient, as analyzed from DOSY spectra, verified that the drug molecules were completely encapsulated in the micelle core. The proportion of anhydrous methyl groups increased with a reduction in the proportion of hydrated methyl groups inside the micelle core. Together with the observations on crosslinked micelles and temperature-induced dehydration of core-forming block, it becomes clear that hydrophobic interaction between anhydrous methyl groups and quercetin could be the reason behind drug solubilization. Finally, we demonstrate that shell-crosslinking of the micelles can be a promising way of improving the loading capacity and prolonging the release for solubilized molecules.