Adsorption of 125I-labeled immunoglobulin G, its F(ab′)2 and Fc fragments onto plasma-polymerized films

Plasma-polymerized films were formed on flat glass plates using allylamine, acrylic acid, acrolein, and allylcyanide as monomers. Adsorption of 125I-labeled-proteins such as immunoglobulin G (IgG), its F(ab′)2 and Fc fragments, and human serum albumin (HSA) was measured on these plasma-polymerized (PP) films covering the glass plates and on commercially available polymer plates. The adsorption isotherm followed the Langmuir equation, from which the binding constant and amount of saturation binding were estimated. We found that, in general, a cationic surface had higher affinity for protein adsorption than an anionic surface. Among the surfaces examined, the PP-allylamine surface showed the highest binding capacity (264.2 nmol/m2) for F(ab′)2 fragment: it was remarkably high. Of the surfaces examined, the PP-acrylic acid surface showed the lowest binding capacity (12.8 nmol/m2) for F(ab′)2 fragment. The PP-acrylic acid surface also indicated the lowest protein binding capacity for IgG (16.5 nmol/m2), Fc-IgG (32.4 nmol/m2) and HSA (16.7 nmol/m2), respectively. These imply that the PP-acrylic acid film is useful to fabricate as a low protein adsorption material which expected to decrease cell adhesion. Results of our investigation indicate that the plasma-polymerization technique is promising for fabrication of a smart NanoBio-interface which can control the protein adsorption on a solid-phase substrate using a suitable monomer such as allylamine for the large adsorption and acrylic acid for the small adsorption.