Dose response in solid-phase radioimmunoassay to human IgG on plasma-polymerized films coated with F (ab′) 2 anti-human IgG antibody

Many amounts of antibody should be fixed in order to increase the sensitivity of an immunoassay. We investigated several materials for their suitability in a solid-phase radioimmunoassay (SPRIA). Nineteen materials were examined, including 10 plasma-polymerized films coated with glass plates (pp-), three plasma-ablated Polyvinylchloride (PVC plate), four commercially available polymers, and one glass and one siliconated glass plate. F(ab′)2 anti-human IgG antibody (100 μg ml−1) was coated with these materials, and the dose response of 125I-protein A uptake to human immunoglobulin G (hIgG) was investigated. The following results were obtained: (1) A small dose response was obtained at 1 μg ml−1 hIgG. Suitable responses were obtained at 10 and 100 μg ml−1 hIgG. (2) Large dose responses were obtained when plasma-polymerized films coated glass and plasma-ablated PVCs such as pp-acrolein, pp-methacrolein, pp-allylalcohol, pp-allylamine, PVC + NH3, PVC + H2O and PVC + HCHO were used. In particular, aldehyde or OH group-containing films show good response of 125I-protein A uptake to hIgG. (3) Dose responses were obtained on substrata having a contact angle of surface between 60 and 90 °.