Gold Nanoparticle-Induced Photocurrent Quenching and Recovery of Polymer Dots: Toward Signal-On Energy-Transfer-Based Photocathodic Bioanalysis of Telomerase Activity in Cell Extracts

Energy transfer (ET) in photoelectrochemical (PEC) bioanalysis is usually generated between noble metal nanoparticles (NPs) and traditional inorganic quantum dots (QDs). Using the innovative polymer dot (Pdot)-involved ET, this work reports the first signal-on and cathodic PEC bioanalysis toward telomerase (TE) activity in cell extracts. Specifically, the sequential binding of capture DNA (cDNA), telomerase primer sequence (TS), and Au NP-labeled probe DNA (Au NP-pDNA) on the electrode would place the Au NPs in close proximity of the Pdots, leading to obvious quenching of the cathodic photocurrent. The subsequent extension of the TS by TE in the presence of deoxyribonucleoside triphosphates (dNTPs) would then release the Ag NP-pDNA from the electrode, leading to the recovery of the photocurrent. On the basis of the Au NP-induced photocurrent quenching and the recovery of Pdots, a sensitive biosensor could thus be developed by tracking the photocurrents to probe the TE activity. This strategy allows for signal-on and cathodic PEC bioanalysis of TE, which can be easily extended for numerous other targets of interest. We believe this work could offer a new perspective for the rational implementation of Pdot-involved ET for advanced PEC bioanalysis.