Poly( -lysine)–GRGDS as a biomimetic surface modifier for poly(lactic acid)

The immobilization of adhesion peptide sequences (such as RGD) at the surfaces of poly(α-hydroxyacid)s, including poly(lactic acid) (PLA), is complicated by an absence of functional groups to support covalent attachment. We demonstrate a method to overcome this problem, by attaching the peptide to poly( -lysine) (PLL), which immobilizes the sequence through adsorption at the poly(α-hydroxyacid) surface. When coated using a 0.01% w/v solution of PLL–GRGDS, bovine aortic endothelial cells seeded upon the modified PLA showed a marked increase in spreading over unmodified PLA. However, inhibition of the cell-spreading effect occurred when using higher concentrations of PLL–GRGDS, which we attribute to the PLL component. This inhibitory effect can be challenged by increasing the amount of GRGDS attached to each PLL molecule. Potentially, this is a flexible method of surface modification that can engineer many different types of tissue engineering scaffolds with a variety of biomolecules, thus allowing initial cell adhesion to be controlled.