A dual-gate organic photoelectrochemical transistor with balanced photoanode voltage for ultrasensitive detection of miRNA-141.

Organic photoelectrochemical transistor (OPECT) has been demonstrated as advanced organic electronic sensing platforms for investigating a wide range of biomolecular species. However, their further development is constrained by the types of electrodes employed and the limitations of fixed signal modulation strategies. Inspired by self-powered photoelectrochemical biosensors with dual-photoelectrodes, a novel operational mode for OPECT was proposed in this work, which disrupted the potential equilibrium between CdS/Eu-MOF and CdIn2S4 dual photoanodes. Specifically, by integrating coenzyme-amplified bioassay technology with Ag+-induced modulation of the photoelectric conversion efficiency at the CdIn2S4 photoanode, the potential balance between the two photoanodes was perturbed to enable signal output. This configuration was embedded within a typical ion-gated circuit featuring an Ag/AgCl-gated poly(3,4-ethylenedioxythiophene): poly-(styrenesulfonate) channel. Through this design, highly sensitive detection of cancer biomarker microRNA-141 was achieved, with a linear detection range from 1 fM to 100 pM and a low limit of detection of 0.76 fM (S/N ≥ 3). This work establishes a biosensing platform with superior detection sensitivity, demonstrating significant potential for advanced biomolecular analysis.