title: Microcalorimetry of the adsorption of lysozyme onto polymeric substrates.
abstract: The conformation of blood proteins adsorbed on biomaterial surfaces probably plays a significant role in the biocompatibility of blood-contacting implants. This paper reports heats of adsorption of a globular protein, lysozyme, onto three uncharged polymeric substrates. Variations in heats among substrates reflect differences in the lysozyme/substrate interaction as well as the possibility of substrate-dependent conformations. In each case, a series of plateaus appeared in the adsorption isotherm with increasing concentration. In the cases of two substrates, polystyrene and poly(styrene-co-butyl methacrylate), endothermic discontinuities appeared at rises between plateaus. It is proposed that the step pattern in each isotherm reflects distinct conformational states of lysozyme on the substrate surfaces. Endothermic discontinuities may be latent heats associated with change to a more stable conformation after initial adsorption. The absence of discontinuities in the case of poly(styrene-co-allyl alcohol) suggests structural transitions occur to a smaller extent on this material and results in conformations different from those which occur when lysozyme is adsorbed by polystyrene or by poly(styrene-co-butyl methacrylate).
authors.affiliation: University of Texas Health Science Center at San Antonio, TX, USA. leev@uthscsa.edu
authors.forename: Valerie A
authors.initials: VA
authors.lastname: Lee
authors.forename: Robert G
authors.initials: RG
authors.lastname: Craig
authors.forename: Frank E
authors.initials: FE
authors.lastname: Filisko
authors.forename: Robert
authors.initials: R
authors.lastname: Zand
mesh_terms: D000327:Adsorption; D001672:Biocompatible Materials / Q000737:chemistry*; D002151:Calorimetry / Q000379:methods*; D008689:Methacrylates / Q000737:chemistry; D008832:Microchemistry; D009113:Muramidase / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D008689:Methacrylates; D011137:Polystyrenes; C481875:poly(styrene-co-allyl alcohol); D009113:Muramidase