[B/F separation systems in enzyme immunoassay].

Methods for bound/free (B/F) separation in enzyme immunoassay are reviewed. In liquid-phase enzyme immunoassays, double antibody methods are used in small laboratories. In solid-phase enzyme immunoassay, which is a more popular and convenient method, antibody (antigen) is usually bound to the support by physical adsorption, and B/F separation is accomplished by washing the solid phase. Covalent binding of proteins, DNA, and oligosaccharides is also possible by using chemically modified supports. Indirect binding of antibody (antigen) to the support mediated by avidin-biotin methods has several merits in comparison with direct methods and double antibody methods. The immune complex transfer method has been used for ultrasensitive assays. The use of magnetic particles as a support can accelerate the immune complex formation, and is becoming more popular in clinical laboratories. A rapid sandwich enzyme immunoassay, using a porous filter as a support, has been developed for dry chemistry.