Formation of the dispersed particles composed of retinol and phosphatidylchiline

Abstract

The purpose of this study was to investigate the dispersal mechanism of retinol (Vitamin A, VA) into phospholipid. VA was dispersed with soybean phosphatidylcholine (PC) using sonication and the dispersal mechanism was evaluated by characterizing the dispersed particles using dynamic light scattering, fluorescence spectroscopy and surface monolayer techniques. The dispersions in the VA mole fraction range of 0.1–0.7 were stable at room temperature for 3 days. A limited amount of VA was incorporated into PC bilayer membranes (approximately 3 mol%). The excess VA separated from the PC bilayers was stabilized as emulsion particles by the PC surface monolayer. When the PC content was less than the solubility in VA (mole fraction of VA: more than 0.8), the PC monolayer did not completely cover the hydrophobic VA particle surfaces. In the case, the particle size increased drastically and the separation into oil/water occurred. The miscibility between VA and PC and the lipid composition were critically important for the stability of the dispersed particles (coexistence of emulsion particles (surface monolayer of PC+core of VA) with vesicular particles (bilayer)) of the lipid mixtures.