Antibody binding, platelet adhesion, and protein adsorption on various polymer surfaces

Commercially available polymer surfaces for in vitro applications are characterized to different extents in terms of hydrophobicity, binding preferences, and immunoglobulin capacity. We compared five, well or poorly defined polystyrene plates, used as standard hydrophobic surfaces for studying biological interactions. Antibody binding (ELISA) and platelet adhesion (release of alkaline phosphatase from adhered platelets) were contrasted with total protein adsorption (alkaline phosphatase assay and bicinchoninic acid assay). In the assays, we utilized four plasma proteins: human serum albumin (HSA), C-reactive protein (CRP), fibronectin, and fibrinogen. At 0.5 μg antigen/well, all antibodies bound to their antigens most effectively on Nunc (MaxiSorp and MediSorp, Waltham, Massachusetts, USA) microplates, as compared to Sarstedt (Nümbrecht, Germany) and Corning microplates (Tewksbury, Massachusetts, USA). The significant differences between Nunc and Corning were seen in the binding of anti-HSA (P ≤ 0.01) and anti-fibronectin (P ≤ 0.0002). Similar patterns were shown in experiments of ADP-induced platelet adhesion to fibrinogen immobilized at 200 μg/well. Platelet adhesion noted on Corning microplates was roughly three times lower compared to those observed on MaxiSorp (P < 0.01), MediSorp (P < 0.02), and Sarstedt (P < 0.05). In a parallel study, we have also shown the superiority of tissue culture-Sarstedt surface over micro test Sarstedt plate. Furthermore, the antibody binding, but not platelet adhesion, was positively correlated with total protein adsorption. Our findings indicate that of five polystyrene surfaces, Nunc microplates are optimal for studies of protein adsorption, as they had the highest binding capacity and relatively the least affected protein structure, pointing to the role of surface chemistry in protein adsorption and adsorption-induced conformational changes in a protein structure.