Influence of block copolymers on the adsorption of plasma proteins to microspheres

SDS-PAGE in combination with densitometry has been used to evaluate the adsorption of plasma and serum proteins to polystyrene microspheres (PS) coated with block copolymers of the poloxamer and poloxamine series. The protein-resistant nature of coated PS was demonstrated for these systems when incubated in dilutions of plasma and serum. The total amount of protein and the type of proteins adsorbed were dependent on the plasma and serum incubation concentration used. At 0.3% serum concentrations the total amount of protein adsorbed was found to be related to the polyoxyethylene (PEO) chain length of the block copolymer, whilst at 0.3% or 50% plasma concentrations a relationship was shown between the polyoxypropylene (PPO) chain and the plasma protein adsorption for the range of block copolymers studied. Immunoblotting studies revealed the adsorption of immunoglobulin G, complement C3, transferrin and fibronectin to all microspheres previously incubated in 50% serum and plasma, whilst fibrinogen was also adsorbed after incubation in 50% plasma; with similar quantities of each protein adsorbed to PS and block copolymer-coated PS.