Conjugation of arginine-glycine-aspartic acid peptides to thermoreversible N-isopropylacrylamide polymers

Thermoreversible polymeric biomaterials are finding increased acceptance in tissue engineering applications. One drawback of the polymers is their synthetic nature, which does not allow direct interaction of mammalian cells with the polymers. This limitation may be alleviated by grafting arginine-glycine-aspartic acid (RGD) containing peptides onto the polymer backbone to facilitate interactions with cell-surface integrins. Toward this goal, N-isopropylacrylamide (NiPAM)-based thermoreversible polymers containing amine-reactive N-acryloxysuccinimide (NASI) groups were synthesized. Conjugation of RGD-containing peptides to polymers was demonstrated with H-1 NMR spectroscopy and reverse-phase high-pressure liquid chromatography. The conjugation reaction was optimal at 4 degreesC and pH of 8.0, and increased with the increasing NASI content of polymers. With a peptide grafting ratio of 0.25 mol %, there was no significant change in the lower critical solution temperature of the polymers. Finally, the NASI-containing polymers, cast as films, on tissue culture polystyrene, were shown to conjugate to RGD-containing peptides and support C2C12 cell attachment. We conclude that NASI-containing thermoreversible polymers are amenable for grafting biomimetic peptides to impart cell adhesiveness to the polymers. (C) 2003 Wiley Periodicals, Inc.