Comparison of resistance to protein adsorption and stability of thin films derived from α-hepta-(ethylene glycol) methyl ω-undecenyl ether on HSi(111) and HSi(100) surfaces

Oligo(ethylene glycol)-terminated thin films were prepared by photo-induced hydrosilylation of α-hepta-(ethylene glycol) methyl ω-undecenyl ether (EG7) on hydrogen-terminated silicon (111) and (100) surfaces. Their resistance to protein adsorption, and stabilities (from hours to days) under a wide variety of conditions, such as air, water, biological buffer, acid, and base, were investigated using contact-angle goniometry and ellipsometry techniques. Results indicated higher stability of the films chemisorbed on Si(111) than on Si(100). Furthermore, micron-sized patterns were fabricated on the films via AFM anodization lithography. Using atomic force microscopy (AFM) and fluorescence microscopy, we demonstrated that various proteins including fibrinogen, avidin, and bovine serum albumin (BSA) predominately adsorbed onto the patterns, but not the rest of the film surfaces.