DNA-silver nanoclusters/polypyrrole nanoparticles: A label-free and enzyme-free platform for multiplexed transcription factors detection

Transcription factors (TFs) regulate information flow from gene to protein, and they are recognized as key indicators to reflect cellular processes. Facile monitoring of TFs may aid diagnostics and treatment, but we still lack of techniques for highly efficient detection of them. In this research, a hybrid material consisting of DNA-silver nanoclusters (DNA-AgNCs) and polypyrrole nanoparticles (PPyNPs) was built for TFs detection. The designed DNA-AgNCs have a hairpin-shaped nucleic acid architecture with a double-stranded stem for recognizing TFs and a single-stranded loop for interacting with PPyNPs. In the absence of TFs, DNA-AgNCs are absorbed to PPyNPs, resulting in fluorescent quenching. While in the presence of TFs, the binding between TFs and the DNA-AgNCs caused desorption of DNA-AgNCs via steric hindrance mechanism. Accordingly, the increase of fluorescence derived from desorption is used for quantifications. Derived from low non-specific protein absorption features of PPyNPs, detection limit of 70 pM for NF-kappa B p50 and 110 pM for p53 were obtained. Then, by absorbing two kinds of DNA-AgNCs to PPyNPs, label-free multiplexed detection of TFs was first realized. Additionally, we suggested that this platform can be developed for drug screening by evaluating inhibitory effect of a pair of optical isomers towards TFs.