EPR SPECTROSCOPY ANALYSIS OF HYDROPHOBICALLY-MODIFIED DEXTRAN-COATED POLYSTYRENE

In order to decrease their hydrophobicity and thus to reduce nonspecif ic protein adsorption, macroporous polystyrene-divinylbenzene (PS-DVB) particles have been coated with dextran. To favor its adsorption, the polysaccharide was previously substituted with low concentrations of phenoxy groups. Different hydrophobically modified dextrans, labeled w ith 4-amino-TEMPO, were allowed to adsorb onto PS-DVB, and the conform ation of polymer chains in the deposited layer was studied by EPR spec troscopy. For a given polymer, it was found that the mobility of chain s increases with the surface coverage. Conversely, the stiffness of th e adsorbed layer was shown to increase with the phenoxy group content of dextran. Furthermore, results of EPR experiments carried out in the presence of bovine serum albumin (BSA) were in good agreement with me asured nonspecific BSA adsorption and were of significance in interpre ting the interaction mechanism between proteins and dextran-modified p olystyrenes. (C) 1998 Academic Press.