The influence of poly(ethylene oxide) grafting via siloxane tethers on protein adsorption

Amphiphilic PEO-silanes (a-c) having siloxane tethers of varying lengths with the general formula alpha-(EtO)(3)si-(CH2)(2)-oligodimethylsiloxane(n)-block-poly(ethylene oxide)(8)-OCH3 [n = 0 (a), n - 4 (b), and n = 13 (c)] were grafted onto silicon wafers and resistance to adsorption of plasma proteins was measured. Distancing the PEO segment from the hydrolyzable triethoxysilane [(EtO)(3)Si] grafting group by a oligodimethylsiloxane tether represents a new method of grafting PEO chains to surfaces. Properties of surfaces grafted with a-c were compared to surfaces grafted with a traditional PEO-silane containing a propyl spacer [(EtO)(3)Si-(CH2)(3)-poly(ethylene oxide)(8)-OCH3, PEO control]. As the siloxane tether length increased, chain density of PEO-silanes grafted onto oxidized silicon wafers decreased and hydrophobicity of the PEO-silane increased which led to a decrease in surface hydrophilicity. Despite decreased surface hydrophilicity, resistance to the adsorption of bovine serum albumin (BSA) increased in the order: PEO control < a < b approximate to c and to human fibrinogen (HF) increased in the order: PEO control < a < b < c. Published by Elsevier Ltd.