Rapid and efficient assembly of functional silicone surfaces protected by PEG: cell adhesion to peptide-modified PDMS

While silicone elastomers generally have excellent biomaterials properties, their hydrophobicity can elicit undesired local biological responses through adsorption and denaturation of proteins. Surface-bound poly(ethylene glycol) (PEG) can ameliorate the situation by preventing contact between the external biology and the silicone elastomer. It is further possible to manipulate the biocompatibility of the surface by linking peptides, proteins or other biological entities to the PEG. Previous synthetic approaches to PEG-protected surfaces are compromised by issues of reproducibility. We describe two rapid and efficient approaches to silicone surface modification by PEG-linked adhesion peptides that overcome this problem: SiH groups are introduced throughout a silicone elastomer during elastomer synthesis or only at the surface after cure; then, in either case, protein-repellent PEG brushes at the surface are introduced by hydrosilylation to give surfaces that can be stored for extensive periods of time without degradation. Activation of the free alcohol with an NSC group followed by immediate conjugation to relevant biological molecules occurs in high yields, as shown for RGDS and GYRGDS. High surface grafting density of the peptides was demonstrated using radiolabeling techniques. Biological activity was demonstrated by a 5-fold increase in cell adhesion on the peptide-modified surfaces when compared to unmodified PDMS control surfaces.