Fast quantification of nucleic acid hybrids by affinity-based hybrid collection.

A hybridization technique for the quantification of nucleic acids is described. In the method a probe pair is allowed to form hybrids with the target nucleic acid in solution. One of the probes has been modified with an affinity label, by which the formed hybrids can be isolated after the reaction. Streptavidin-agarose was used to capture hybrids containing biotinylated DNA. The hybrids were measured using radioiodine as label on the second probe. The rate of the hybridization reaction in solution is fast, allowing the whole procedure to be carried out in 3 h. The method is quantitative with a detection limit of 4 X 10(5) molecules (0.67 attomoles) target DNA. The test is insensitive to impurities in biological samples, which are analyzed without purification of the target DNA. Non-isotopic measurement of the hybrids can also be applied. In this case the hybrids are bound to microtitration wells and detected spectrophotometrically by peroxidase-catalyzed colour development.