Polymer brushes and self-assembled monolayers: Versatile platforms to control cell adhesion to biomaterials (Review)

This review focuses on the surface modification of substrates with self-assembled monolayers (SAMs) and polymer brushes to tailor interactions with biological systems and to thereby enhance their performance in bioapplications. Surface modification of biomedical implants promotes improved biocompatibility and enhanced implant integration with the host. While SAMs of alkanethiols on gold substrates successfully prevent nonspecific protein adsorption in vitro and can further be modified to tether ligands to control in vitro cell adhesion, extracellular matrix assembly, and cellular differentiation, this model system suffers from lack of stability in vivo. To overcome this limitation, highly tuned polymer brushes have been used as more robust coatings on a greater variety of biologically relevant substrates, including titanium, the current orthopedic clinical standard. In order to improve implant-bone integration, the authors modified titanium implants with a robust SAM on which surface-initiated atom transfer radical polymerization was performed, yielding oligo(ethylene glycol) methacrylate brushes. These brushes afforded the ability to tether bioactive ligands, which effectively promoted bone cell differentiation in vitro and supported significantly better in vivo functional implant integration.