Abstract: A diagnostic reagent is disclosed which is capable of binding to a target nucleotide sequence which is bound to a labeled polynucleotide in a target binding region which is at least partially co-extensive with the target binding region in the probe polynucleotide which is capable of binding to the target nucleotide sequence. A method is disclosed in which the reagent is contacted with a sample and with a capturing polynucleotide under conditions such that target nucleotide which may be present in the sample binds to the probe polynucleotide and displaces labeled polynucleotide from the reagent complex, and the capturing polynucleotide binds selectively to the displaced labeled polynucleotide in the region of the labeled polynucleotide that had been bound to the probe polynucleotide. Determination of the displaced nucleotide gives a value which is a function of the presence and concentration of target nucleotide in the sample.

Abstract: A diagnostic reagent is disclosed containing a complex of a probe polynucleotide (P) bound via purine/pyrimidine hydrogen bonding to a labeled polynucleotide (L). The probe (P) contains a target binding region (TBR) capable of binding to a target nucleotide sequence (G) of a biological sample. A method is disclosed in which contact with a sample containing the target nucleotide sequence (G) causes binding, initially between G and a single-stranded portion (IBR) of the target binding region (TBR). Thereafter the labeled polynucleotide (L) is displaced from the complex by branch migration of (G) into the (P)/(L) binding region. A volume excluding polymeric agent such as poly(ethylene oxide) (PEO or PEG) or other polyethers enhances the rate of appearance of displaced labeled polynucleotide. Determination of displaced labeled polynucleotide (L) gives a value which is a function of the presence and concentration of target nucleotide sequence (G) in the sample.

Abstract: A diagnostic reagent is disclosed containing a complex of a probe polynucleotide (P) bound via purine/pyrimidine hydrogen bonding to a labeled polynucleotide (L). The probe (P) contains a target binding region (TBR) capable of binding to a target nucleotide sequence (G) of a biological sample. A method is disclosed in which contact with a sample containing the target nucleotide sequence (G) causes binding, initially between G and a single-stranded portion (IBR) of the target binding region (TBR). Thereafter the labeled polynucleotide (L) is displaced from the complex by branch migration of (G) into the (P)/(L) binding region. Determination of displaced labeled polynucleotide (L) gives a value which is a function of the presence and concentration of target nucleotide sequence (G) in the sample.