PREPARATION AND CHARACTERIZATION OF POLYSTYRENE MICROSPHERES SURFACE-MODIFIED WITH GLUCOSIDE MOIETIES

The emulsifier-free emulsion copolymerization of 2-(glucosyloxy) ethyl methacrylate (GEMA) and styrene (St), yielded a series of copolymer microspheres [poly(GEMA-co-St) microspheres] with varying content of the GEMA moiety. 2-[(2-Ethylphosphatoethyl)dimethylammonio]ethyl 4,4'-azobis(4-cyanovalerate) (EAP-501) and potassium persulfate (KPS) were used as initiators. From the copolymerization of GEMA and St it was found that the initial rate of polymerization of St increased in the presence of a small amount of GEMA. Poly(GEMA-co-St) microspheres showed unimodal distribution of particle sizes with 240-440 nm, which depended on mol% of GEMA to St in feed and species of initiator. The zeta-potential of the particles was nearly zero (0 approximately - 9mV) and -68 approximately -99 mV for poly(GEMA-co-St) microspheres produced by EAP-501 and KPS, respectively. From XPS measurements the GEMA moiety was found located on the surface of the particles. Poly(GEMA-co-St) microspheres with a hydrophilic surface suppressed the adsorption of albumin (Alb) and globulin (Glo), less than the poly(St) microspheres as the control. It was concluded that the suppression of adsorption of a protein onto poly(GEMA-co-St) microspheres is dependent on hydrophilicity due to the GEMA moiety and ammonium phosphate group derived from EAP-501 on the surface of particles.