Abstract: Nucleic acid probes are immobilized on polystyrene surfaces such as the wells of microtiter plates for use in solution phase nucleic acid sandwich hybridization assays, particularly those using large branched DNA amplification multimers, by: (a) cleansing the surface by washing it sequentially with a strong acid, a strong base, and water, (b) passively adsorbing a polypeptide having primary amino groups onto the cleansed surface, and (c) covalently bonding the probe to the adsorbed polypeptide via a base-stable bifunctional crosslinking agent, and (d) subjecting the surface to conditions that simulate the hybridization conditions used in the assay.

Abstract: In one aspect of this invention, various protein/nucleic acid hybrid probes are described which can be used to amplify the detectable signal in immunoassays. The protein moiety is capable of functioning either as an antibody or an antigen. The nucleic acid moiety serves as a signal amplifier. In another aspect, various methods of amplifying the detectable signal in immunoassays by use of the hybrid probes and related polynucleotide probes are disclosed.