Self-Cleaning Recyclable Multiplexed Photoelectrochemical Sensing Strategy Based on Exonuclease III-Assisted Signal Discrimination

For discriminating the signals of multi-targets, multiplexedphotoelectrochemical(PEC) detection is generally accomplished by modulating the lightsource or voltage, which prospect is usually limited by expensiveinstrumentation, tedious operational steps, and time-consuming materialscreening. To realize multiplexed determination on single photoelectricinterface using the routine technique, a non-instrument-assisted strategyfor signal discrimination needs to be explored. Herein, we proposean exonuclease III-mediated multiple PEC signals resolution strategyand construct a self-cleaning recyclable multiplexed PEC sensor usinga porphyrin-bipyridine-based covalent organic framework (Por-Bpy COF)photocathode. Specifically, following the dual-target recognitionevent, exonuclease III cleaves the DNA strand attached to the magneticbead so that the two signal labels can be separated. Once the signallabel binds to the DNA on the electrode surface (E-DNA), exonucleaseIII turns to excise the DNA strand of the signal label and consequentlythe E-DNA can repeatedly bind different signal labels. As a result,distinguishable photocurrent signals of different targets can be generatedon a single photoelectric interface. The feasibility of this multiplexedsensor is verified by detecting two coexisting mycotoxins aflatoxinB1 and zearalenone. On account of eliminating the instrumentationconstraints and simplifying the experimental procedures, the proposedsensing strategy may provide a brand-new idea for the explorationof portable multiplexed PEC sensing devices.