Grafting amine-terminated branched architectures from poly(L-lactide) film surfaces for improved cell attachment

Poly(L-lactide) (PLL) has been used as a bioabsorbable material in the medical and pharmaceutical fields. The unmodified hydrophobic PLL surface generally has low cell affinity; thus, modification of PLL film surface properties is necessary to improve its use as a biomaterial. Our surface modification method involved the use of photografting and typical wet chemistry to create branched architectures containing amine functionalities on the periphery of the grafted layers. Amine (-NH2) groups were first introduced on the PLL film surface by photoinduced grafting of 4,4'-diaminobenzophenone and the grafted branched architectures were created by subsequent reactions with succinic acid and tris(2-aminoethyl) amine. The resulting film surface was analyzed using contact angle goniometry and X-ray photoelectron spectroscopy. MC3T3 fibroblasts were cultured on unmodified PLL film and PLL films grafted with the branched structures and the films were subsequently analyzed by optical microscopy. The contact angle goniometry results showed an initial decrease and subsequent plateau in the water contact angles for the PLL films with each successive generation of the branched architectures. The X-ray photoelectron spectroscopy data provided insight into the structure of the grafted layer and revealed an increase in the nitrogen content with each generation. Optical micrographs showed enhanced cell attachment and viability on the surface-modified PLL films.