Biomimetic antifouling PDMS surface developed via well-defined polymer brushes for cardiovascular applications

Abstract

Despite the distinct advantages of poly(dimethylsiloxane) (PDMS) for biomedical applications, because of its hydrophobic nature, suffers from non-specific protein adsorption and platelet adhesion and activation when used as a blood-contacting material. To confer hydrophilicity and biomolecules repelling characteristics, well-defined and high-density poly(2-hydroxyethyl methacrylate) (PHEMA) brushes are synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP) on the PDMS substrate. First, PDMS surface is activated using an ultraviolet/ozone (UVO) wet treatment in water media to introduce hydroxy moieties without scarifying the surface property resulting a crack-free SiO2 surface. Then, 3-(2-bromoisobutyramido)propyl(trimethoxy)silane (BrTMOS), the active ATRP initiator, is immobilized on the UVO-treated PDMS surface to prepare a thin layer of hydrophilic PHEMA brush on PDMS substrate exhibiting excellent protein and platelet resistance. PHEMA brushes supply a biomimetic feature by combining antifouling properties due to hydrophilic characteristic with bioactive properties resulted from the presence of a high density hydroxy groups, which are subsequently used for biomolecules conjugation. The results indicate that grafting of PHEMA chains on the PDMS surface enhances the surface wettability which leads to a decrease in non-specific protein adsorption and platelet adhesion compared to the bare PDMS substrate. The adhered platelets on the PHEMA-tethered PDMS substrate maintain their normal round morphology. Furthermore, the conjugated gelatin macromolecules onto the tethered PHEMA chains promote the adherence and growth of human umbilical vein endothelial cells via ligand-receptor interactions.