Characterization and analysis of osteopontin-immobilized poly(2-hydroxyethyl methacrylate) surfaces.

A wide array of technologies exist for the characterization and quantification of molecules present at surfaces. We have used several of these experimental and instrumental techniques for the analysis of a novel biomaterial surface. Osteopontin, an extracellular matrix molecule involved in wound-healing processes, has been chosen as a relevant model protein to immobilize onto poly(2-hydroxyethyl methacrylate) [poly(HEMA)]. Electron spectroscopy for chemical analysis and time-of-flight secondary ion mass spectrometry were used to verify the surface chemistry and the presence of protein. Iodination of osteopontin yielded quantitative data supportive of dose-dependent immobilization. Enzyme-linked immunosorbent assay was also used to investigate the presence of osteopontin on poly(HEMA). Finally, the cell adhesive properties of immobilized osteopontin were confirmed by using a bovine aortic endothelial cell adhesion assay. The use of multiple tools to characterize the many facets of a biomaterial surface will undoubtedly improve our understanding of the surface and facilitate the amelioration of in vivo performance.