Protein−Silicone Interactions:  How Compatible Are the Two Species?

Protein-on-silicone and silicone-on-protein films were made by the sequential coating of the human serum albumin (HSA) onto silicone films on glass or vice versa. The silicones used were either trimethylsilyl-terminated poly(dimethylsiloxane) (unfunctionalized PDMS) or (triethoxysilyl)propyl-terminated poly(dimethylsiloxane) (functionalized TES−PDMS). Angular-dependent X-ray photoelectron spectroscopy (AD-XPS) and contact angle measurements (CA) were used to characterize the modified surfaces. Irrespective of the order of building the films, protein-on-silicone or silicone-on-protein both showed essentially identical surface compositions, suggesting a significant degree of mixing between the protein and silicone. The TES−PDMS was found to have a greater affinity for HSA: thicker and more homogeneous silicone films were found with TES−PDMS/HSA than with PDMS/HSA films.