Enhanced cathodic photocurrent derived from N-type S doped-Bi2WO6 nanoparticles through an antenna-like strategy for photoelectrochemical biosensor

Construction of built-in correction photoelectrochemical sensing platform for diagnosis of Alzheimer's disease

The occurrence of Alzheimer's disease (AD) is strongly associated with the progressive aggregation of a 42-amino-acid fragment derived from the amyloid-β precursor protein (Aβ1-42). Therefore, it is crucial to establish a versatile platform that can effectively detect Aβ1-42 to aid in the early-stage preclinical diagnosis of AD. Herein, we introduce a specialized split-type analytical platform that enables sensitive and accurate monitoring of Aβ1-42 based on a self-corrected photoelectrochemical (PEC) sensing system. To realize this design, gelatinized Ti3C2@Bi2WO6 Schottky heterojunctions were prepared and served as photoelectrodes for tackling the photoinduced charge carriers. Functionalized CaCO3@CuO2 nanocomposites were used as signal converters to detect Aβ1-42 and amplify the signal further. Benefiting from the glucose oxidation induced acid microenvironment and H2O2 output, the nanocomposites are able to rapidly decompose, producing Ca2+ and Fenton-like catalyst Cu2+. The Cu2+-driven Fenton-like reaction generated ·OH, which accelerated the 3,3',5,5'-tetramethylbenzidine (TMB) oxidation. Additionally, Ca2+ was cross-linked with alginate inducing gelation on the surface of Ti3C2@Bi2WO6 Schottky heterojunctions, influencing mass transfer and light absorption. Eventually results in the shift of photocurrent, allowing for precise quantification with a detection limit of 0.06 pg mL-1. The combination of colorimetric variation and the photoelectric effect provide a more accurate and reliable result. This research opens up new possibilities for constructing PEC platforms and beyond.

Photocathodic Activation of Peroxymonosulfate in a Photofuel Cell: A Synergetic Signal Amplification Strategy for a Self-Powered Photoelectrochemical Sensor

A self-powered photoelectrochemical (PEC) sensor has attracted widespread attention in the field of analysis, but it is still a challenge to enhance its response signals with rational strategies. In this work, a novel self-powered PEC sensing platform was developed for the quantitative detection of gatifloxacin (GAT) based on a photofuel cell consisting of two types of ZIF-derived ZnO/Co3O4 heterojunctions as photoactive materials. Peroxymonosulfate (PMS) was first used as an electron acceptor coupled with a photofuel cell to develop a synergetic signal amplification strategy. In a dual-photoelectrode system, the PMS activation on the ZnO@Co3O4 photocathode not only accelerated electron transfer from the Co3O4@ZnO photoanode to achieve strong signal intensity but also improved the sensing sensitivity by the oxidation reaction of generated highly active radicals to GAT. Compared with the absence of electron acceptors, the introduction of PMS produced a 2-fold enhancement in the signal output performance and a more than 72-fold improvement in the signal sensitivity. For the construction of the sensing interface, a molecularly imprinted polymer was assembled on the photocathode to specifically recognize GAT. The proposed sensor exhibited a detection range of 10-1 to 105 pM with a detection limit of 0.065 pM. The proposed sensing method has the advantages of sensitivity, simplicity, reliable stability, and anti-interference ability, which opens the door to the design of high-performance self-powered PEC sensors.

Recent Trends in Self-Powered Photoelectrochemical Sensors: From the Perspective of Signal Output

Revolutionary developments in analytical chemistry have led to the rapid development of self-powered photoelectrochemical (PEC) sensors. Different from conventional PEC sensors, self-powered PEC sensors do not require an external power source or complex devices for the sensitive detection of targets. As a result, these sensors have enormous application potential for the development of novel portable sensors. An increasing body of work is making excellent progress toward the implementation of self-powered PEC sensors for detection, but there have been no reviews to date. The present review first introduces the state of the art in the development of self-powered PEC sensors. Then, different types of self-powered PEC sensors are summarized and discussed in detail, including their current, power, and potential. Additionally, single- and dual-photoelectrode systems are classified and systematically compared. Finally, the current developments and major challenges that need to be addressed are also summarized. This review provides valuable insights into the current state of self-powered PEC sensors to promote further progress in this field.

A self-powered photoelectrochemical biosensing platform for H-FABP monitoring mediated by CsPbBr3@COF-V

Advanced bioelectronic detection based on the integration of modern optical electronics and biological systems has a broad prospect. The strategy of cathode signal amplification in self-powered photoelectrochemical (PEC) immunosensors with excellent performance is rarely reported in the field of immune analysis. Herein, the work demonstrates a self-powered PEC biosensor formed with BiOI photocathode and WO3/SnS2/ZnS photoanode, and CsPbBr3@COF-V was used as the photocathode signal quenching source for the quantitative monitoring of heart fatty acid binding protein (H-FABP). The high efficiency and stable self-powered biosensor formed not only provides continuous and powerful photocurrent response for bioanalysis through reasonable stepped band structure, but also effectively eliminates the interference of reducing substances. The quenching source CsPbBr3@COF-V greatly affects the photocurrent response due to steric hindrance, weak conductivity, competition with the substrate for dissolved oxygen and excitation light source. And the intervention of this key factor achieves multiple signal amplification effect and opens up an innovative vision for self-powered PEC immunosensor. Taking H-FABP as a representative analyte, the proposed signal amplification self-powered photoelectrochemical presents a broad linear range from 0.0005 to 150 ng/mL with the detection limit of 0.19 pg/mL.

Self-powered photoelectrochemical/visual sensing platform based on PEDOT/BiOBr0.8I0.2 organic-inorganic hybrid material and MWCNTs/SnS2 heterojunction for the ultrasensitive detection of programmed death ligand-1

Programmed death ligand-1 (PD-L1) can enhance the immune tolerance of tumor cells by suppressing the activity of T-cells, and is one of the culprits that lead to the immune escape of tumor cells. Thus, the sensitive and portable detection of PD-L1 levels is essential for many types of tumor prognosis. Herein, a novel dual-mode analytical device for the ultrasensitive detection of PD-L1 has been developed. In this configuration, an advanced organic-inorganic hybrid material of poly(3,4-ethylenedioxythiophene) -BiOBr0.8I0.2 is designed as photocathode to enhance the photogenerated electron migration efficiency of the MWCNTs/SnS2-photoanode by external circuit, amplifying cathodic photocurrent without extra energy supply. The PD-L1 aptamer is loaded on the photocathode surface to ensure selectivity. The obtained sensing platform can achieve highly sensitive and specific detection of PD-L1 in complex environment, with a low detection limit of 0.29 pg mL-1. On the other hand, electrochromic material Prussian blue (PB) and MWCNTs/SnS2 are integrated to fabricate a portable sensing chip for PD-L1. Under illumination, photogenerated electrons of MWCNTs/SnS2 are injected into Prussian blue, and the blue PB is reduced to white product, indicating the concentration of PD-L1, without need of other instrument. This self-powered photoelectrochemical and visual analysis system has good practicability and is a promising clinical diagnosis tool.

Bismuth Tungstate Nanoplates-Vis Responsive Photocatalyst for Water Oxidation

The development of visible-light-responsive (VLR) semiconductor materials for effective water oxidation is significant for a sustainable and better future. Among various candidates, bismuth tungstate (Bi2WO6; BWO) has attracted extensive attention because of many advantages, including efficient light-absorption ability, appropriate redox properties (for O2 generation), adjustable morphology, low cost, and profitable chemical and optical characteristics. Accordingly, a facile solvothermal method has been proposed in this study to synthesize two-dimensional (2D) BWO nanoplates after considering the optimal preparation conditions (solvothermal reaction time: 10-40 h). To find the key factors of photocatalytic performance, various methods and techniques were used for samples' characterization, including XRD, FE-SEM, STEM, TEM, HRTEM, BET-specific surface area measurements, UV/vis DRS, and PL spectroscopy, and photocatalytic activity was examined for water oxidation under UV and/or visible-light (vis) irradiation. Famous commercial photocatalyst-P25 was used as a reference sample. It was found that BWO crystals grew anisotropically along the {001} basal plane to form nanoplates, and all properties were controlled simultaneously by tuning the synthesis time. Interestingly, the most active sample (under both UV and vis), prepared during the 30 h solvothermal reaction at 433 K (BWO-30), was characterized by the smallest specific surface area and the largest crystals. Accordingly, it is proposed that improved crystallinity (which hindered charge carriers' recombination, as confirmed by PL), efficient photoabsorption (using the smallest bandgap), and 2D mesoporous structure are responsible for the best photocatalytic performance of the BWO-30 sample. This report shows for the first time that 2D mesoporous BWO nanoplates might be successfully prepared through a facile template-free solvothermal approach. All the above-mentioned advantages suggest that nanostructured BWO is a prospective candidate for photocatalytic applications under natural solar irradiation.

Photo-assisted Zn-air battery-driven self-powered aptasensor based on the 2D/2D Schottky heterojunction of cadmium-doped molybdenum disulfide and Ti3C2Tx nanosheets for the sensitive detection of penicillin G

A novel photocatalyzed Zn-air battery-driven (ZAB)-based aptasensor has been manufactured using the two dimensional (2D)/2D Schottky heterojunction as photocathode and Zn plate as photoanode. It was then employed to sensitively and selectively detect penicillin G (PG) in the complex environment. The 2D/2D Schottky heterojunction was established by the in situ growth of cadmium-doped molybdenum disulfide nanosheets (Cd-MoS₂ NSs) around Ti₃C₂T_x NSs (denoted as Cd-MoS₂@Ti₃C₂T_x) by using phosphomolybdic acid (PMo₁₂) as precursor, thioacetamide as sulfur source, and Cd(NO₃)₂ as a doping agent through the hydrothermal method. The gained Cd-MoS₂@Ti₃C₂T_x heterojunction possessed contact interface, hierarchical structure, and plenty of sulfur and oxygen vacancies, thus showing the enhanced separation ability of photocarriers and electron transfer. Due to the enhanced UV-vis light adsorption ability, high photoelectric conversion efficiency, and exposed catalytic active sites, the constructed photocatalyzed ZAB displayed a boosted output voltage of 1.43 V under UV-vis light irradiation. The developed ZAB-driven self-powered aptasensor demonstrated an ultralow detection limit of 0.06 fg mL^-1 within a PG concentration ranged from 1.0 fg mL^-1 to 0.1 ng mL^-1, as deduced from the power density-current curves, along with high specificity, good stability and promising reproducibility, as well as excellent regeneration ability and wide applicability. The present work provided an alternative analysis method for the sensitive analysis of antibiotics based on the portable photocatalyzed ZAB-driven self-powered aptasensor.

PEDOT/FeOOH/BiVO4 Nanohybrids with Excellent Photoelectric Performance Promoted by Photothermal Effects for the Ultrasensitive Detection of MicroRNA-375-3p

Herein, a novel photoactive poly(3,4-ethyl-enedioxythiophene) (PEDOT)/FeOOH/BiVO₄ nanohybrid with excellent photoelectrochemical (PEC) efficiency was assembled for the construction of an ultrasensitive biosensor for microRNA-375-3p (miRNA-375-3p) detection. In comparison with the traditional FeOOH/BiVO₄ photoactive composite, the PEDOT/FeOOH/BiVO₄ nanohybrids exhibited markedly enhanced photocurrent due to the promoted interfacial charge separation by PEDOT, which was used not only as an electron conductor but also as a localized photothermal heater to enhance the photogenerated carrier separation. Based on this PEDOT/FeOOH/BiVO₄ photoelectrode and an enzyme-free signal amplification strategy including a target-induced catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR), a PEC sensing platform for the detection of miRNA-375-3p was established, achieving a wide linear range from 1 fM to 10 pM with a low detection limit of 0.3 fM. Moreover, this work provides a general photocurrent enhancement strategy for the development of high-performing PEC biosensors for sensitive detection of biomarkers and early disease diagnosis.

Codoping g-C3N4 with boron and graphene quantum dots: Enhancement of charge transfer for ultrasensitive and selective photoelectrochemical detection of dopamine

The development of superior photoelectrochemical (PEC) sensors for biosensing has become a major objective of PEC research. However, conventional PEC-active materials are typically constrained by a weak photocurrent response owing to their limited surface-active sites and high electron-hole recombination rate. Here, a boron and graphene quantum dots codoped g-C₃N₄ (named GBCN) as PEC sensor for highly sensitive dopamine (DA) detection was fabricated. GBCN exhibited the greatest photocurrent response and PEC activity compared to free g-C₃N₄ and g-C₃N₄ doped with boron. The proposed PEC sensor for DA determination exhibited a broad linear range (0.001-800 μM) and a low detection limit (0.96 nM). In particular, a sensitivity up to 10.3771 μA/μM/cm² was seen in the case of GBCN. The high PEC activity can be attributed to the following factors: (1) the boron and graphene quantum dots co-doping significantly increased the specific surface area of g-C₃N₄, providing more adsorption sites for DA; (2) the dopants extended the absorption intensity of g-C₃N₄, red-shifting the absorption from 470 to 540 nm; and (3) the synergism of boron and graphene quantum dots efficiently boosted the photogenerated electrons migration from the conduction band of g-C₃N₄ to graphene quantum dots, facilitating charge separation. In addition, GBCN also exhibited good anti-interference ability and stability. This research may shed light on the creation of a highly sensitive and selective PEC platform for detecting biomolecules.

Current development of stretchable self-powered technology based on nanomaterials toward wearable biosensors in biomedical applications

In combination with the growing fields of artificial intelligence and Internet-of-things (IoT), the innovation direction of next-generation biosensing systems is toward intellectualization, miniaturization, and wireless portability. Enormous research efforts have been made in self-powered technology due to the gradual decline of traditional rigid and cumbersome power sources in comparison to wearable biosensing systems. Research progress on various stretchable self-powered strategies for wearable biosensors and integrated sensing systems has demonstrated their promising potential in practical biomedical applications. In this review, up-to-date research advances in energy harvesting strategies are discussed, together with a future outlook and remaining challenges, shedding light on the follow-up research priorities.

Z-scheme Bi2O3/CuBi2O4 heterojunction enabled sensitive photoelectrochemical detection of aflatoxin B1 for health care, the environment, and food

Designing a photoelectrochemical (PEC) biosensor with preponderant sensitivity and anti-interference is a challenge for detecting small molecules in real samples with complex matrices. To this end, the Bi₂O₃/CuBi₂O₄ was synthesized in one step to enhance visible light's absorption ability, transferring the interfacial carrier's efficiency, a high-active Z-scheme heterojunction, and a photocathode biosensor was proposed. For the first time, we used the density functional theory to verify a Z-scheme transfer pathway of photogenerated electrons in Bi₂O₃/CuBi₂O₄ and the energy band structure of Bi₂O₃ and CuBi₂O₄, respectively. Bi₂O₃/CuBi₂O₄-based PEC biosensor was developed for competive immunoassay of small molecular, aflatoxin B1 (AFB1) as an example, resulting in a low detection limit of 297.4 fg/mL and a linear range of 1.4 pg/mL-280 ng/mL in urine, water, peanut, and wheat samples. Using spiked experiments, the satisfied repeatability, reproducibility, stability, and specificity of the Bi₂O₃/CuBi₂O₄-based PEC biosensor indicated a promise for application in health care, the environment, and food.