Protein and lipid adsorption by acrylic hydrogels and their relation to water wettability

Radiochemical techniques were applied to determine protein and lipid uptake by acrylic hydrogels. The water wettability of these gels was previously obtained by using contact angle goniometry and was found to depend mainly on the composition of the polymer matrix but not on the equilibrium water content. Three hydrogels, poly(hydroxyethyl acrylate), poly(glyceryl methacrylate), and poly(acrylamide), had approximately the same equilibrium water content, therefore the same approximate penetrability with respect to protein. The uptake of both the protein (bovine serum albumin) and the lipid (cholesteryl oleate) appeared to be directly related to the water–gel interfacial tension, whereas the ease of removal was inversely related to water wettability. A cationic preservative, benzalkonium chloride, increased the protein uptake somewhat for two of the hydrogels. Preexposure to proteinaceous solutions had a pronounced effect, increasing the lipid uptake by the hydrogels, with the exception of PGMA. The results obtained appear to support the minimum interfacial free‐energy hypothesis of biocompatibility.