Monitoring oligonucleotide binding processes using chemiluminescence quenching

Method for detecting and / or quantifying a nucleic acid target in a sample comprising: contacting said sample with an oligonucleotide sequence containing at least one probe sequence that can bind to said target nucleic acid in which the said oligonucleotide is labeled with each of at least one chemiluminescent molecule and at least one quencher molecule that can attenuate the chemiluminescence of said chemiluminescent molecule, the molecules being arranged chemiluminescent and quencher so that the interaction thereof changes depending on whether the probe sequence is bonded to said target nucleic acid, so that in one state bound or unbound such chemiluminescence is attenuated substantially, and in the other thereof there is reduced of attenuation or no attenuation not chemiluminescence; and change the conditions to cause the chemiluminescent molecule to undergo a chemiluminescent reaction; and monitoring the chemiluminescence emission and comparing said emission with that corresponding to the absence of said target nucleic acid.