Detectable labeled nucleoside analogs and methods of use thereof

A method for detecting the presence or absence of a target nucleic acid in a test sample, comprising:

• a) contacting the test sample with a composition comprising an oligo- or poly nucleotide probe wherein the oligo- or polynucleotide probe comprises a detectable label of formula:
• base is
• wherein sugar is covalently bonded to N1 of the base;
• wherein R1 is —NHC(O)NH2;
• wherein R2 is —H or alkyl;
• each of X, Y, and Z is independently —H, —OH, —O-alkyl, —SH, —SR4, —NHR4, —NR4R5,
• wherein R3 is H or metal;
• R4 is —H or alkyl;
• R5 is —H or alkyl;
• linker is (CH2CH2O)nCH2CH2, (CH2CH2O)n, (CH2O)n or (CH2)n;
• wherein n is an integer from 1 to 30;
• Q is O, S, or NH;
• label is a colorimetric, chemiluminescent, bioluminescent, a fluorescent compound, or a non- or weakly fluorescent compound;
• wherein the oligonucleotide probe is capable of selectively or specifically hybridizing with the target nucleic acid under conditions of moderate stringency;
• optionally exposing the sample to light of said excitable wavelength;
• and
• b) detecting whether said contacting produces a change in color or fluorescence emission of the composition;
• such that a change in color or fluorescence emission of the composition indicates that the target nucleic acid is present in the test sample.