Alkaline Phosphatase-Mediated Bioetching of CoOOH/BiVO4 for Signal-On Organic Photoelectrochemical Transistor Bioanalysis

Dual Engine Boosts Organic Photoelectrochemical Transistor for Enhanced Modulation and Bioanalysis

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 (gm) against the single-photoelectrode ones. Moreover, the light irritation upon the device effectively shifts the peak value of gm 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.

MXene-Enhanced Bi2S3/CdIn2S4 Heterojunction Photosensitive Gate for DEHP Detection in a Signal-On OPECT Aptamer Biosensor

Organic electrochemical transistors with signal amplification and good stability are expected to play a more important role in the detection of environmental pollutants. However, the bias voltage at the gate may have an effect on the activity of vulnerable biomolecules. In this work, a novel organic photoelectrochemical transistor (OPECT) aptamer biosensor was developed for di(2-ethylhexyl) phthalate (DEHP) detection by combining photoelectrochemical analysis with an organic electrochemical transistor, where MXene/Bi2S3/CdIn2S4 was employed as a photoactive material, target-dependent DNA hybridization chain reaction was used as a signal amplification unit, and Ru(NH3)63+ was selected as a signal enhancement molecule. The poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-based OPECT biosensor modulated by the MXene/Bi2S3/CdIn2S4 photosensitive material achieved a high current gain of nearly a thousand times at zero bias voltage. The developed signal-on OPECT sensing platform realized sensitive and specific detection of DEHP, with a detection range of 1-200 pM and a minimum detection limit of 0.24 pM under optimized experimental conditions, and its application to real water samples was also evaluated with satisfactory results. Hence, the construction of this OPECT biosensing platform not only provides a promising tool for the detection of DEHP but also reveals the great potential of the OPECT application for the detection of other environmental toxins.

Signal Modulation of Organic Photoelectrochemical Transistor by a Z-Scheme Photocathodic Gate: An Innovative Dual Amplification Strategy for Sensitive Aptasensing Application

Pursuing a more efficient signal amplification strategy is highly demanded for improving the performance of the promising cathodic photoelectrochemical (PEC) sensors. In this work, we present an extremely effective dual signal amplification strategy by the integration of a Z-scheme nanohybrids-based photocathode with the effective signal modulation of an organic photoelectrochemical transistor (OPECT) device. Specifically, photocathodic gate material of CdTe-BiOBr nanohybrids with a Z-scheme electron-transfer route was designed and synthesized for preliminary improvement of the activity of the photogate; afterward, signal modulation of the OPECT system by the photocathodic gate of CdTe-BiOBr was then accomplished for further signal amplification by 2 orders of magnitude. As a result, the output PEC signal of CdTe-BiOBr was enhanced by 17.5-fold as compared to BiOBr, and the channel current (IDS) of the OPECT device was 117-fold magnified than its gate current (IG) response. Exemplified by tetracycline (TC) as a model target and aptamer as the specific recognition element, a versatile cathodic aptasensing platform was constructed based on the proposed OPECT device. The introduced OPECT aptasensor merits advantages, including a good linear range (1.0 × 10-12 to 1.0 × 10-6 M), a low limit of detection (4.2 × 10-13 M), and superior sensitivity than the traditional PEC methods for TC detection, which represents a universal protocol for developing the innovative photocathodic OPECT sensing platform toward accurate analysis.

Metallointercalated-DNA Nanotubes as Functional Light Antenna for Organic Photoelectrochemical Transistor Biosensor with Minimum Background

Organic photoelectrochemical transistor (OPECT) biosensor with a removed background is desired but remains challenging. So far, scientists still lack a solution to this issue. The light-matter interplay is expected to achieve an advanced OPECT with unknown possibilities. Here, we address this challenge by tailoring a unique heterogeneous light antenna as the functional gating module and its cascade interaction with a proper channel, which is exemplified by bioinduced [Ru(bpy)2dppz]2+-intercalated DNA nanotubes (NTs)/NiO heterojunction and its modulation against a diethylenetriamine-treated poly(ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) channel. Light stimulation of the antenna can generate the obvious cathodic photocurrent and, hence, modulate the channel, accomplishing OPECT with a minimal background and the hitherto highest current gain of 19 000. Linking with nucleic acid hybridization using microRNA-155 as the representative target, the device achieves sensitive biosensing down to 5.0 fM.

Polymer Dot-Gated Accumulation-Type Organic Photoelectrochemical Transistor for Urea Biosensing

Organic photoelectrochemical transistor (OPECT) biosensing represents a new platform interfacing optoelectronics and biological systems with essential amplification, which, nevertheless, are concentrated on depletion-type operation to date. Here, a polymer dot (Pdot)-gated accumulation-type OPECT biosensor is devised and applied for sensitive urea detection. In such a device, the as-designed Pdot/poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) is validated as a superior gating module against the diethylenetriamine (DETA) de-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) channel, and the urea-dependent status of Pdots has been shown to be sensitively correlated with the device's response. High-performance urea detection is thus realized with a wide linear range of 1 μM-50 mM and a low detection limit of 195 nM. Given the diversity of the Pdot family and its immense interactions with other species, this work represents a generic platform for developing advanced accumulation-type OPECT and beyond.