Growth of human cells on plasma polymers: putative role of amine and amide groups

The attachment and growth of human endothelial cells and fibroblasts was studied on polymer surfaces fabricated by the polymerization of volatile amine and amide compounds in a low pressure gas plasma, and by the treatment of various surfaces in ammonia plasmas, which served to increase the nitrogen content of the surface layers. Infrared spectra showed the presence of amide groups, including those cases where the volatile compound ('monomer') did not contain oxygen. The performance of the surfaces in cell attachment correlated with the surface hydrophilicity and the nitrogen content, although for the latter a fair degree of scatter indicated that a more complex relationship applies. All these surfaces supported the attachment and growth of human cells. Generally, amide plasma polymers were best but the individual monomer and the plasma parameters also played a role. From comparisons of the various surfaces, it is suggested that the amide group is the main promoter of cell attachment in nitrogen-containing plasma surfaces.