Protein adsorption from buffer and plasma onto hydrophilic—hydrophobic poly(ethylene oxide)—polystyrene multiblock copolymers

Abstract

The influence of substrate hydrophilic—hydrophobic balance on the adsorption of proteins from buffer and plasma was investigated using a series of amphiphilic multiblock copolymers composed of poly(ethylene oxide) (PEO) and polystyrene (PS). Adsorption of albumin, fibrinogen, and immunoglobulin G was monitored from single-component buffer, multicomponent buffer, and plasma solutions in contact with polymer-coated beads. Protein adsorption from buffer demonstrated kinetics and adsorption totals that correlated to the hydrophilic—hydrophobic content of the PEOPS surfaces; however, no significant correlations existed between bulk composition, in vitro, and ex vivo blood compatibility tests. From plasma, adsorption to the surfaces showed two interesting results. First, minimum levels of protein adsorption witnessed on a PEOPS (40% PEO) copolymer were not observed in the competitive adsorption of the same species from buffer. These results were correlated to minimum platelet adhesion and activation in vitro and optimal whole blood compatibility ex vivo. Second, fibrinogen uptake from plasma exhibited transient, fluctuating kinetics on both the PEO and PS homopolymer surfaces while two PEOPS copolymer surfaces showed no fluctuations. Overall, few correlations between buffer adsorption, plasma adsorption, or resulting in vivo and ex vivo analyses were observed. This suggests that buffered systems oversimplify the protein adsorption scenario and lack significant correlations to surface interactions in whole blood and plasma.