Self-Circulation Oxygen-Hydrogen Peroxide-Oxygen System for Ultrasensitive Cathode Photoelectrochemical Bioassay Using a Stacked Sealed Paper Device

In this work, a self- circulation oxygen-hydrogen peroxide-oxygen (O-2-H2O2-O-2) system with photogenerated electrons as fuel and highly active hemin monomers as operators was engineered for ultrasensitive cathode photoelectrochemical bioassay of microRNA-141 (miRNA-141) using a stacked sealed paper device. During the circulation, the photogenerated electrons from BiVO4/Cu2O photosensitive structures assembled on a reduced graphene oxide paper electrode first reduced the electron acceptors (dissolved O-2) to H2O2, which was then catalytically decomposed by hemin monomers to generate O-2 again. The regenerated O-2 continued to be reduced, which made O-2 and H2O2 stuck in the infinite loop of O2H2O2-O-2 accompanied by the fast consumption of photogenerated electrons, generating an amplified photocurrent signal. When a target existed, a duplex-specific nuclease-induced target recycling reaction with dual trigger DNA probes as the output was performed to initiate the assembly of bridge-like DNA nanostructures, which endowed the self-circulation system with dual destruction functions as follows. (i) Reduced fuel supply: the assembled DNA bridges acting as a negatively charged barrier prevented the photogenerated electrons from participating in the O-2 reduction to H2O2. (ii) Incapacitation of operators: DNA bridging induced the dimerization of hemin monomers linked on the DNA hairpins to catalytically inactive hemin dimers, leading to the abortive regeneration of O-2. These destruction functions resulted in the circulation interruption and a remarkably decreased photocurrent signal. Thus, the developed cathode photoelectrochemical biosensing platform achieved ultrasensitive miRNA-141 detection with a linear range of 0.25 fM to 1 nM and a detection limit of 83 aM, and it also exhibited high accuracy, selectivity, and practicability.

Automated summary

A self-circulation oxygen-hydrogen peroxide-oxygen system with photogenerated electrons as fuel and hemin monomers as operators was engineered for ultrasensitive cathode photoelectrochemical bioassay of microRNA-141. The system achieved ultra-sensitive miRNA-141 detection with a wide linear range, low detection limit, high accuracy, selectivity, and practicability.