Preparation of a chemically anchored phospholipid monolayer on an acrylated polymer substrate

This paper describes a strategy for designing a chemically anchored phospholipid monolayer that could be used as coating materials for biomedical implants. To make a chemically anchored phospholipid monolayer on the polymer substrate, we prepared the mono-acrylated phospholipid (1-palmitoyl-2-[12-(acryloyloxy)-dodecanoyl]-sn-glycero-3-phosphocholine; acryloyl-PC) and the acrylated polymer (poly(octadecylacrylate-co-4-acryloyloxy butylacrylate)), which was synthesized by the acrylation of poly(octadecyl acrylate-co-hydroxybutyl acrylate, poly(OA-co-HA)) with acryloyl chloride. The chemically anchored phospholipid monolayer was prepared by using in situ photopolymerization of a pre-assembled phospholipid monolayer, produced by lipid vesicle fusion, onto the acrylated polymer coated silicon wafer. Optimal condition of vesicle fusion and irradiation time was determined from the degree of hydrophilicity rendered by the polymerized phospholipid surface. The physicochemical properties of polymerized phospholipid monolayer on the substrate were evaluated using water contact angle, field-emission scanning electron micrograph (FE-SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). These results confirmed that the polymerized phospholipid monolayer was chemically anchored on the acrylated polymer substrate. The chemically anchored phospholipid monolayer was stable in aqueous condition for 2 weeks, but the physically adsorbed phospholipid monolayer got removed within 1 day. Moreover, the polymerized phospholipid monolayer also suppressed albumin absorption and platelet adhesion, in vitro. This polymerized phospholipid monolayer provides a new biomimetic system for coating medical devises.