Yuan-Cheng Zhu

Organic photoelectrochemical transistor (OPECT) holds significant promise for bioanalysis, but its application is constrained by dual-voltage requirements. Here, we constructed a Bi-MOF@CdS@Au/DNA-gated self-powered OPECT for enrofloxacin (ENR) detection by integrating a solar cell between the source and drain electrodes. The presence of ENR initiates specific binding with the aptamer, which induces aptamer dissociation from the electrode surface and, consequently, enhances electron transfer efficiency. This enhances the photogenerated gate voltage and promotes cation migration, leading to a marked decrease in channel current (I_DS). The platform demonstrates good analytical capabilities, showing a wide linear detection range from 100 pg/mL to 100 μg/mL (R² = 0.993) with a detection limit of 0.568 pg/mL (S/N = 3). This work demonstrates that the self-powered OPECT provides a promising platform for environmental monitoring applications.

While existing graphene oxide frameworks (GOF) are extensively studied in various energy devices, no effort has been made to explore their potentials in organic photoelectrochemical transistor (OPECT) bioanalysis. Here, we introduce a GOF-gated OPECT, where the photocathodic and nanozymatic synergies of a layered porphyrin (Fe)-cross-linked GOF are synergistically harnessed to achieve enhanced-mode OPECT bioanalysis. The peroxidase-mimicking and photocathodic-responding properties of the as-prepared GOF could not only trigger the biomimetic precipitation (BMP) but also enable the photogating of a polyethylenimine-dedoped PEDOT:PSS channel. Linking with a magnetic separation-assisted hybridization chain reaction amplification correlating the target microRNA-17, the BMP could severely block its layered structure, consequently inducing the inhibition of interfacial charge and mass transfer and thus a pronounced gating effect. The good analytical performance of the developed OPECT bioanalysis is validated by experiments with a detection limit as low as 1 fM. This study demonstrates the potential of GOF in OPECT bioanalysis. Considering the large family of functional GOF, its implications are expected in OPECT.

Neuromorphic perception capable of multisensory integration (MSI) in electrolytes is important but remains challenging. Here, the aqueous implementation of artificial MSI is reported based on the newly emerged organic photoelectrochemical transistor (OPECT) by representative visual (light)‐gustatory (sour) perception. Under the co‐modulation of light and H⁺/OH⁻, multisensory synaptic plasticity and several typical MSI characteristics are mimicked, including “super‐additive response,” “inverse effectiveness effect” and “temporal congruency.” To demonstrate its potential usage, different types of multisensory associative learning and corresponding reflex activities are further emulated. The chemical MSI system is also utilized to control artificial salivation by a closed loop of real‐time perception, processing, integration, and actuation to emulate the biological responses toward external stimuli. In contrast to previous solid‐state operations, this work offers a new strategy for developing neuromorphic MSI in aqueous environments that are analogous to those in biology.

Organic photoelectrochemical transistor (OPECT) has shown substantial potential in the development of next-generation bioanalysis yet is limited by the either-or situation between the photoelectrode types and the channel types. Inspired by the dual-photoelectrode systems, we propose a new architecture of dual-engine OPECT for enhanced signal modulation and its biosensing application. Exemplified by incorporating the CdS/Bi₂S₃ photoanode and Cu₂O photocathode within the gate-source circuit of Ag/AgCl-gated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) channel, the device shows enhanced modulation capability and larger transconductance (g_m) against the single-photoelectrode ones. Moreover, the light irritation upon the device effectively shifts the peak value of g_m to zero gate voltage without degradation and generates larger current steps that are advantageous for the sensitive bioanalysis. Based on the as-developed dual-photoelectrode OPECT, target-mediated recycling and etching reactions are designed upon the CdS/Bi₂S₃, which could result in dual signal amplification and realize the sensitive microRNA-155 biodetection with a linear range from 1 fM to 100 pM and a lower detection limit of 0.12 fM.

The organic photoelectrochemical transistor (OPECT) has been proven to be a promising platform to study the rich light-matter-bio interplay toward advanced biomolecular detection, yet current OPECT is highly restrained to its intrinsic electronic amplification. Herein, this work first combines chemical amplification with electronic amplification in OPECT for dual-amplified bioanalytics with high current gain, which is exemplified by human immunoglobulin G (HIgG)-dependent sandwich immunorecognition and subsequent alkaline phosphatase (ALP)-mediated chemical redox cycling (CRC) on a metal-organic framework (MOF)-derived BiVO₄/WO₃ gate. The target-dependent redox cycling of ascorbic acid (AA) acting as an effective electron donor could lead to an amplified modulation against the polymer channel, as indicated by the channel current. The as-developed bioanalysis could achieve sensitive HIgG detection with a good analytical performance. This work features the dual chemical and electronic amplification for OPECT bioanalysis and is expected to stimulate further interest in the design of CRC-assisted OPECT bioassays.

Nowadays, the emerging photoelectrochemical (PEC) bioanalysis has drawn intensive interest due to its numerous merits. As one of its core elements, functional nanostructured materials play a crucial role during the construction of PEC biosensors, which can not only be employed as transducers but also act as signal probes. Although both chemical composition and morphology control of nanostructured materials contribute to the excellent analytical performance of PEC bioassay, surveys addressing nanostructures with different dimensionality have rarely been reported. In this review, according to classification based on dimensionality, zero-dimensional, one-dimensional, two-dimensional, and three-dimensional nanostructures used in PEC bioanalysis are evaluated, with an emphasis on the effect of morphology on the detection performances. Furthermore, using the illustration of recent works, related novel PEC biosensing patterns with promising applications are also discussed. Finally, the current challenges and some future perspectives in this field are addressed based on our opinions.

The design and development of a 3D hierarchical CdS/NiO heterojunction and its application in a self-powered cathodic photoelectrochemical (PEC) bioanalysis is introduced. Specifically, NiO nanoflakes (NFs) were in situ formed on carbon fibers via a facile liquid-phase deposition method followed by an annealing step and subsequent integration with CdS quantum dots (QDs). The glucose oxidase (GOx) was then coated on the photocathode to allow the determination of glucose. Under 5 W 410 nm LED light and at a working voltage of 0.0 V (vs. Ag/AgCl), this method can assay glucose concentrations down to 1.77×10⁻⁹ M. The linear range was 5×10⁻⁷ M to 1×10⁻³ M, and the relative standard deviation (RSD) was below 5%. The photocathodic biosensor achieved target detection with high sensitivity and selectivity. This work is expected to stimulate more passion in the development of innovative hierarchical heterostructures for advanced self-powered photocathodic bioanalysis. Graphical abstract Design of 3D hierarchical CdS/NiO heterojunction and its application in a self-powered cathodic photoelectrochemical (PEC) bioanalysis.

Photoelectrochemical (PEC) cytosensors, a combination of the PEC process and the living‐cell assay, have emerged as a powerful tool in the analytical and biological science. This mini review provides a brief introduction of this arena and summaries the key steps about the development of PEC cytosensors with representative examples, followed by future prospects based on our own opinions.