Effectiveness of detergents in blocking nonspecific binding of IgG in the enzyme-linked immunosorbent assay (ELISA) depends upon the type of polystyrene used.

Since nonspecific binding of immunoglobulins to polystyrene is a major factor in the nonspecific reactions observed in the ELISA, we studied the effect of a nonionic detergent (Tween-20) on the binding of human IgG to polystyrene. Pretreatment of polystyrene with detergent did not provide a permanent barrier to adsorption of IgG, because washing with water completely removed the blocking ability of detergents from low-binding plates, but only partially removed the blocking power from high-binding plates. On high-binding plates, human IgG molecules suspended in detergent solution attached to the plastic surface, an effect not seen with low-binding plates. Consequently, the binding power of the plastic that is used greatly affects the ability of nonionic detergents to prevent nonspecific binding of immunoglobulins.