Achieving Ultralow Fouling Performance for Poly(Hydroxy-Functional Methacrylates) Grafted Surfaces via Atom Transfer Radical Polymerization

Abstract

The development of nonfouling biomaterials to prevent nonspecific protein adsorption and cell/bacterial adhesion is critical for many biomedical applications, such as antithrombogenic implants and biosensors. In this work, we synthesize and characterize two polymer brushes on the gold substrate by using surface-initiated atom transfer radical polymerization (SI-ATRP) of Hydroxy-Functional Methacrylates monomers: HEMA and HPMA. We investigate the effect of film thickness on protein adsorption from single protein solution to complex human blood media, as well as bacterial adhesion. Surface plasmon resonance (SPR) results show a correlation between antifouling properties and film thickness, that is, optimal film thickness of 25-45 nm for polyHPMA and 20-45 nm for polyHEMA is obtained to achieve almost zero protein adsorption (< 0.3 ng/cm2) from single protein solution, 10% human blood plasma, and 10% human blood serum. Furthermore, polyHEMA brushes remain its excellent resistance to 100% human serum and plasma with < 5 ng/cm2 adsorption amount, while polyHPMA brushes adsorb more proteins of 13.5 ng/cm2 and 50.0 ng/cm2 from 100% human serum and plasma, respectively. More strikingly, static bacteria adhesion assay shows that there are almost no bacteria adhered to polyHEMA and polyHPMA surfaces as compared to full coverage of bacteria on the bare gold surface. In addition, stability tests show a very stable polyHPMA and polyHEMA surfaces without polymer degradation within 20 days. PolyHEMA and PolyHPMA provide effective nonfouling biomaterials, alternative to poly (ethylene glycol), to highly resist nonspecific protein adsorption and cell/bacteria adhesion.