In the sandwich hybridization ELISA assay format, the antigen ligand and antibodies in ELISA are replaced with a nucleic acid analyte, complementary oligonucleotide capture and detection probes.
Generally, in the case of nucleic acid hybridization, monovalent salt concentration and temperature are controlled for hybridization and wash stringency, contrary to a traditional ELISA, where the salt concentration will usually be fixed for the binding and wash steps (i.e. PBS or TBS). Thus, optimal salt concentration in hybridization assays varies dependent upon the length and base composition of the analyte, capture and detection probes.