Physicochemical Studies on the Phospholipid Bilayer Incorporated Sialoglycolipid

Abstract

With the intention of obtaining a novel liposome as a drug carrier able to avoid clearance by the reticuloendothelial system (RES), the authors synthesized two sialoglycolipids, i.e., 2-O-(8-hexadecanoylamino-3, 6-dioxaoctyl)-β-N-acetylneuraminic acid sodium salt (Sia-t-pa) and 2-O-[8-(2-hexadecyloctadecanoylamino)-3, 6-dioxaoctyl]-β-N-acetylneuraminic acid sodium salt (Sia-t-psa) and modified the surface of their liposomal membrane.Sia-t-pa was found to be eluted from the liposomal membrane by serum albumin, whereas Sia-t-psa was not, using the gel filtration method. In order to clarify the reason why there was such a difference between Sia-t-pa and Sia-t-psa, we investigated the properties of the phospholipid bilayer-incorporated sialoglycolipids physicochemically.The effect of the anchor structure of the sialoglycolipids, i.e., single acyl chain (Sia-t-pa) or double acyl chain (Sia-t-psa), on the fluidity and calorimetric properties was noticeably different. It was inferred that the effect was attributable to a difference in the position of the sialoglycolipid incorporated in the bilayer membrane.