Determination of the concentration of transcription factor by using exonuclease III-aided amplification and gold nanoparticle mediated fluorescence intensity: A new method for gene transcription related enzyme detection.

Herein, we report a new probe for the determination of the concentration of NF-κB p50, one kind of DNA-binding transcription factors (TFs), by using Exonuclease III (Exo III)-aided amplification and gold nanoparticle mediated fluorescence intensity. Since TFs play critical roles in various biological processes, the detection of TFs can provide a lot of useful biological information for studding gene expression regulation related disease. In our system, in the presence of transcription factor, Exo III based amplification reaction was trigged. This enzymatic digestion results in the release of intermediate DNA and ultimately liberating the fluorophore (which, separated from the quencher of AuNP and BHQ2, now fluoresces). The released intermediate DNA then hybridizes with another strand3, whence the cycle starts anew. So, the fluorescence intensity reflects the NF-κB p50 concentration with a detection limit of 1.32 pM. Importantly, this method might be further extended to selectively detect various dsDNA-binding proteins by simply changing the binding-site sequences of strand1/strand2 duplex probes.