Anti-protein and anti-bacterial behavior of amphiphilic silicones

Silicones with improved water-driven surface hydrophilicity and anti-biofouling behavior were achieved when bulk-modified with poly(ethylene oxide) (PEO)-silane amphiphiles of varying siloxane tether length: alpha-(EtO)(3)Si-(CH2)(2)-oligodimethylsiloxanem-block-poly(ethylene oxide)(8)-OCH3 (m = 0, 4, 13, 17, 24, and 30). A PEO8-silane [alpha-(EtO)(3)Si-(CH2)(3)-PEO8-OCH3] served as a conventional PEO-silane control. To examine anti-biofouling behavior in the absence versus presence of water-driven surface restructuring, the amphiphiles and control were surface-grafted onto silicon wafers and used to bulk-modify a medicalgrade silicone, respectively. While the surface-grafted PEO-control exhibited superior protein resistance, it failed to appreciably restructure to the surface-water interface of bulk-modified silicone and thus led to poor protein resistance. In contrast, the PEO-silane amphiphiles, while less protein-resistant when surface-grafted onto silicon wafers, rapidly and substantially restructured in bulk-modified silicone, exhibiting superior hydrophilicity and protein resistance. A reduction of biofilm for several strains of bacteria and a fungus was observed for silicones modified with PEO-silane amphiphiles. Longer siloxane tethers maintained surface restructuring and protein resistance while displaying the added benefit of increased transparency.