Poly(ethylene oxide)-modified carboxylated polystyrene latices--immobilization chemistry and protein adsorption

alpha,omega-Diamino poly(ethylene oxides) (PEOs) with different molecular weights (148, 1000, and 3400) were covalently immobilized onto carboxylated polystyrene latices. The immobilization of PEO was carried out with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) in aqueous media. The reaction conditions were optimized to obtain a maximal coupling of PEO. The degree of coupling was determined by the surface concentration of amino groups. The maximal surface concentrations of amino groups were close to what is expected for a complete coverage of the surface with PEO. Adsorption of albumin from a buffer solution onto PEO-containing surfaces was about 85% less than the albumin uptake by unmodified polystyrene latices. Protein adsorption from plasma dilutions was lower on surfaces containing PEO molecules with a higher molecular weight. The reduction of the protein uptake from plasma by surfaces containing PEO-3400 molecules was only 40% compared to the adsorption to unmodified surfaces. These results indicate that plasma proteins have a low affinity for surfaces modified with PEO. However the PEO modified surfaces are by no means 'protein resistant' when exposed to plasma.