Protein adsorption from plasma onto poly(n-alkyl methacrylate) surfaces

Protein adsorption of human serum albumin (HSA), human fibrinogen (Fg), human immunoglobulin G (IgG), high density lipoprotein (HDL) and high molecular weight kininogen (HMWK) from plasma onto poly (n-alkyl methacrylate) (PAMA) surfaces was measured using a semi-quantitative enzyme-immunoassay. Adsorption was investigated for PAMA(n = 1) (n is the number of C-atoms in the n-alkyl side chain), PAMA(n = 8) and PAMA(n = 18). PAMA(n = 1) has a relatively hydrophilic surface as compared to the more hydrophobic PAMA(n = 8) surface. Both polymers have surface chains which do not reorient after contact with water. The PAMA(n = 18) surface is relatively hydrophobic but in this case polymer surface chains and segments are able to reorient after contact with water. Protein adsorption was measured both as a function of time and as a function of the plasma dilution. If adsorption from plasma was measured as a function of time no exchange of proteins could be observed. The amount of adsorbed protein was always larger in the case of the hydrophobic PAMA(n = 8) as compared to PAMAS(n = 1 and 18), probably due to hydrophobic interactions between the proteins and the PAMA(n = 8) surface. At high plasma concentration relatively large amounts of HDL adsorb onto PAMA(n = 8), indicating that this lipoprotein preferentially adsorbs onto this surface.