DIFFUSE-REFLECTANCE FOURIER-TRANSFORM INFRARED-SPECTROSCOPY OF PHOSPHOLIPID ADSORPTION ONTO SILICIC-ACID

Diffuse reflectance Fourier transform infrared spectroscopy was used to study the mode of adsorption of phosphatidylcholine (PC) in hexane onto silicic acid (SA). PC adsorption was mainly through the charged phosphate group with minimal binding through the ester carbonyl. When the SA surface with adsorbed PC is washed with hexane, containing a small concentration of isopropanol, the desorbed PC is recovered without structural change, i.e., there is no evidence of PC hydrolysis in the adsorption process. Adsorbent moisture probably promotes PC adsorption due to the increased availability of surface water hydroxyl groups for interaction with the PC phosphate groups. Isopropanol promoted PC binding by destabilizing PC reverse miscelles in solution, thus promoting its adsorption.