Rationalising the design of polymeric thermoresponsive biomaterials.

We investigated the cell adhesion and growth of a series of thermoresponsive copolymers of N-isopropylacrylamide (NIPA) and N-tert-butylacrylamide (NtBA) above their lower critical solubility temperatures (LCST). It was found that cell adhesion and growth on the solvent cast films improved with increasing the NtBA content in the copolymers. The improvement was dependent on cell line. The surfaces of copolymers were analysed by atomic force microscopy. The topography of polymer films was not dependent on composition. The differences in the cell attachment and growth were attributed to the variation of surface energy with composition. The surface energy of copolymers decreased with the increase in the NtBA content. We conclude that poly(N-isopropylacrylamide) (poly(NIPA)) is a relatively poor substrate for cell growth and proliferation. However, its ability to support cell growth can be significantly improved by suitable modification.