Advanced organic bioelectronics enable smooth fusion between modern electronics and biological systems for better physiological monitoring and pathological examinations. Photon-regulated bioelectronics are especially desirable due to the non-contact impact, remote-control, and even selfpowered operation. However, few studies have addressed the advanced photon-enabled organic photoelectrochemical transistor (OPECT) biosensors capable of operation at zero gate bias. Here, on the basis of a hydrogel/graphene oxide hybrid (denoted as HGH), a multifunctional HGH-gated OPECT biosensor is presented, which is exemplified by Ca 2+ -triggered gelation on the CdS quantum dot (QD) photoelectrode linking with a sandwich immunoassay toward human IgG as the model target. Gelation of HGH on the CdS QD gate electrode can not only inhibit the interfacial mass transfer on the gate/ electrolyte interface, but also significantly block the light absorption of CdS QDs, leading to the corresponding change of the channel currents of OPECT device. At zero gate bias, this OPECT biosensor exhibits high gain in response to light and good analytical performance for human IgG with a detection limit of 50 fg mL -1 . Given the numerous intelligent hydrogel materials and their potential interactions with light, this work unveils a general platform for developing a new class of hydrogel-gated OPECT bioelectronics and beyond.
Although great advances have been achieved in the field of organic electrochemical transistor (OECT) biodetection, its fundamental sensing principles are still highly limited. Different from current dominating protocols for OECT biodetection, herein, the bio‐dependent regulation of light‐sensitive gate electrode for transducing the corresponding biological events is introduced. Exemplified by the enzymatically catalytic growth of gold nanoclusters to gold nanoparticles on the 3D TiO2/carbon fiber matrix gate electrode, the photoelectrochemistry of the hybrid gate photoanode shifts from the type‐II heterojunction to plasmonic type, rendering reduced photon‐to‐electron efficiency and thus decreased current response of the gate photoanode. By connecting to an alkaline phosphatase‐associated sandwich immunoassay event toward the representative analyte of C‐reactive protein, the model system exhibits target‐dependent tunability and good analytical performance at zero gate bias. A new sensing principle for OECT biodetection is manifested, and would spur more creativity to explore the rich light–matter interplay for advanced OECT biodetection.
Nature makes use of molecular charges to operate specific biological synthesis and reactions. Targeting advanced opto-bioelectronic sensors, organic photoelectrochemical transistors (OPECTs), taking advantage of the light fuel substituting an external gate potential, is now debuting and expected to serve as a universal platform for studying the rich light–biomatter interplay for new bioanalytics. Given the ubiquity of charged biomolecules in nature, molecular charge manipulation should underpin a generic route for innovative OPECT regulation and operation, which nevertheless has remained unachieved. Herein, this work manifests the biological tuning of surface charge toward the OPECT biosensor, which was exemplified by a light-sensitive CdS quantum dot (QD) gate electrode interfaced by a smart DNA superstructure with adenosine triphosphate (ATP) responsiveness. Highly negative-charged supramolecular DNA concatemers were self-assembled via sequential hybridization, and the ATP-triggered disassembly of the DNA concatemers would cause a tandem change of the effective gate voltage and transfer characteristics with significantly improved resolution. The present opto-bioelectronic device translates the events of charged molecules into amplified electrical signals and outlines a generic format for the future exploitation of rich biological tunability and light–biomatter interplay for innovative bioanalytics and beyond.
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