THE EFFECT OF TEMPERATURE-SENSITIVE COMB-BLOCK COPOLYMERS ON PROTEIN ADSORPTION RESISTANCE OF POLYSTYRENE MICROSPHERES

Thermo-sensitive poly(N-isopropylacrylamide)(PNIPAM)-poly(N-vinylpyrrolidone)(PVP)and PNIPAM-poly(ethylene oxide)(PEO)comb-block copolymers with PVP and PEO hydrophilic branches,respectively,were synthesized using RAFT polymerization of NIPAM and PVP or PEO macromonomers.Polystyrene(PS)microspheres were treated in aqueous suspension with different copolymers obtained to allow polymer adsorbing on PS microsphere surface.Protein adsorption resistance of the PS microsphere with pre-adsorbed copolymer was evaluated,using lysozyme as the model protein,by flocculating test,particle coagulation(by dynamic light scattering),electrophoretic mobility measurement and quantitative analysis of protein adsorption.It was found that pre-adsorption of the comb-block copolymer on PS microsphere surface could effectively inhibit protein adhesion to the surface.A larger number of hydrophilic branches in the copolymer resulted in a better protein resistance both at room temperature and at temperatures higher than the LCST of PNIPAM.Transmission electron microscopy and dynamic light scattering measurements of the copolymer colloids confirmed that the hydrophilic branches formed an outer adsorb-layer and provided resistance to protein when the copolymer adsorbed on PS microsphere surface.Moreover,flocculation tests on heating and cooling of PS microsphere suspension in the presence of protein provided a simple and effective method to qualitatively evaluate the protein resistance of the polymers used for pre-adsorption treatment.