Measurements of water sorption enthalpy on polymer surfaces and its effect on protein adsorption

The molar enthalpy of sorption (Delta H-m(s)) of water vapor onto three polymer surfaces and its effect on nonspecific protein adsorption were investigated by inverse gas chromatography (IGC). The values of Delta H-m(s) measured by IGC were found to be -16.9 +/- 1.2, -18.6 +/- 1.3, and -29.9 +/- 2.4 kJ/mole for polystyrene (PS), polymethylmethacrylate (PMMA), and poly(2-hydroxyethyl methacrylate) (PHEMA), respectively, over a temperature range of 333-423 K. Protein adsorption to three polymer-coated substrates was conducted as a function of the bulk protein concentration using lysozyme, fibrinogen, and bovine serum albumin (BSA), and the amount of adsorbed protein was measured by the solution depletion method. For a given bulk protein concentration, a larger amount of protein is adsorbed on PS and PMMA surfaces which have greater Delta H-m(s) than that of PHEMA surfaces. Although Delta H-m(s) for PS and PMMA are close to each other. PS surfaces were found to exhibit a higher adsorption affinity than PMMA surfaces over the proteins and concentrations investigated. Our results indicate that the strength of water-polymer interactions and the functional groups on the polymer surface are important factors for controlling the amount of nonspecifically adsorbed protein. Published by Elsevier B.V.