Poly(vinyl alcohol) as a blocking agent in enzyme immunoassays.

We examined the blocking ability of poly(vinyl alcohol) (PVA) in enzyme immunoassays by coating polystyrene microtiter wells with PVA of different molecular weights (MW) and percent hydrolysis (%Hyd). Blocking ability was measured by the differences in non-specific binding of an anti-rabbit IgG-horseradish peroxidase conjugate to coated and uncoated wells. PVA with a MW of 124,000-186,000 and > 99 %Hyd was the most effective in suppressing the binding of the conjugate. This PVA at 0.5% (w/v) was significantly better at reducing non-specific binding than commonly used blocking agents and did not interfere with the specific binding of the conjugate to antigen-coated microtiter wells.