Patent ID: 7868161

Claim:
A method of determining the presence of a target nucleic acid molecule in a sample, said method comprising: contacting a probe molecule with a sample comprising a target nucleic acid molecule, wherein the probe molecule comprises one or more 5-halo-4-thiouracil nucleobases, wherein each of the one or more 5-halo-4-thiouracil nucleobases is a 5-chloro-4-thiouracil nucleobase or a 5-fluoro-4-thiouracil nucleobase, and wherein the target nucleic acid comprises a thymidine; irradiating the sample for a period of time at a wavelength at which the one or more 5-halo-4-thiouracil nucleobases is selectively photoexcited to form between a 5-halo-4-thiouracil nucleobase of the probe molecule and the thymidine of the target nucleic acid a fluorescent crosslinked product comprising a fluorophore having the structure of Formula (I): wherein Y is selected from the group consisting of H, C 1 -C 5 linear or branched alkyl, cyano, nitro, carboxy, —NR 1 R 2 , —C(O)R 3 , and —NH—C(O)—R 4 , wherein R 1 , R 2 , R 3 , and R 4 are selected from H and C 1 -C 5 alkyl; and detecting the fluorescence of the fluorophore of Formula (I) at a chosen emission wavelength, thereby determining the presence of a target nucleic acid molecule in the sample.