The effect of the chemical structure of the phospholipid polymer on fibronectin adsorption and fibroblast adhesion on the gradient phospholipid surface

The interaction between biocomponents and the polyethylene (PE) surface modified with poly[ω-methacryloyloxyalkyl phosphorylcholine (MAPC)] was considered taking into account the surface characteristics, i.e., density, mobility, and orientation of the poly(MAPC). The PE surface, grafted gradually with the poly(MAPC) was prepared by corona irradiation method. The amount of peroxide produced on the PE surface which was determined with 1,1- diphenyl-2-picryl-hydrazyl, increased with an increase in the energy of the corona. The surface density of the poly(MAPC) was increased with an increase in the amount of the peroxides produced by the corona irradiation. The orientation and mobility of the poly(MAPC) grafted on the PE surface was evaluated with 1,6-diphenyl-1,3,5-hexatriene. The orientation of the poly[6- methacryloyloxyhexyl phosphorylcholine (MHPC)] which has six methylene chains between the phospholipid polar group and the backbone was higher than that of other poly(MAPC)s. The mobility of the poly(MAPC) decreased with an increase in the methylene chain length in the MAPC unit. The fibronectin adsorption on the gradient PE sheet grafted with poly(MAPC) was determined with enzyme- labeled immunoassay. The amount of adsorbed fibronectin on the PE grafted with poly[2-methacryloyloxyethyl phosphorylcholine (MPC)] and poly(MHPC) decreased with an increase in their surface density. Especially, the PE sheet grafted with the poly(MHPC) was effectively reduced compared with other poly(MAPC)s. On the poly[10-methacryloyloxydecyl phosphorylcholine (MDPC)], there is a minimum amount of adsorbed fibronectin. The fibronectin adsorption pattern on the PE sheet grafted with poly(MAPC) was quite different from the chemical structure of the MAPC unit. The human normal diploid fibroblasts (WI-38 cells) were cultured on the gradient PE sheet grafted with poly(MAPC) changing the concentration of seeded WI-38 cells. The adhesion behavior of the WI-38 cells was different depending on the concentration of the seeded WI-38 cells. When the concentration was low, the number of the adherent WI-38 cells had the same tendency as fibronectin adsorption. The gradient PE sheet grafted with the poly(MHPC) effectively reduced WI-38 cells adhesion even when the concentration of the WI-38 cells was high. The biocompatibility of polymer surfaces can be improved by highly oriented phosphorylcholine group.