Antigen down format photoelectrochemical analysis supported by fullerene functionalized Sn3O4

Carbon-based photoelectrochemical sensors: recent developments and future prospects

Owing to the considerable potential of photoelectrochemical (PEC) sensors, they have gained significant attention in the analysis of biological, environmental, and food markers. However, the limited charge mass transfer efficiency and rapid recombination of electron hole pairs have become obstacles in the development of PEC sensors. In this case, considering the unique advantages of carbon-based materials, they can be used as photosensitizers, supporting materials and conductive substrates and coupled with semiconductors to prepare composite materials, solving the above problems. In addition, there are many types of carbon materials, which can have semiconductor properties and form heterojunctions after coupling with semiconductors, effectively promoting the separation of electron hole pairs. Herein, we aimed to provide a comprehensive analysis of reports on carbon-based PEC sensors by introducing their research and application status and discussing future development trends in this field. In particular, the types and performance improvement strategies of carbon-based electrodes and the working principles of carbon-based PEC sensors are explained. Furthermore, the applications of carbon-based photoelectric sensors in environmental monitoring, biomedicine, and food detection are highlighted. Finally, the current limitations in the research on carbon-based PEC sensors are emphasized and the need to enhance the sensitivity and selectivity through material modification, structural design, improved device performance, and other strategies are emphasized.

Ultrasensitive photoelectrochemical immunosensor based on Dual-Photosensitive electrodes

In the study, a photoelectrochemical (PEC) immunosensor based on dual-photosensitive electrodes was developed for cardiac troponin I (cTnI) detection. The sensing photocathode with biometric functions was prepared by CuInS₂ and narrow band gap semiconductor In₂S₃ as the counter electrode. In this way, the separation of photoanode and biometric events was realized, and the ability of stability of the immunosensor could be effectively improved. Moreover, the attraction to the photogenerated electrons (e^-) from photoanode would be increased by the abundant holes (h⁺) of photocathode, under the radiation of light. This tremendously improves the photoelectric response, which further improves the sensitivity of the immunosensor. The controllable-synthesis uncomplicated photoelectric material not only accords with the principle of simplicity of electrode modification but also makes the immunosensor more conducive to the practical application. Additionally, even in the case of zero bias voltage, the constructed PEC immunosensor can operate with high efficiency, namely, self-powered. The immunosensor could provide the quantitative readout photocurrent to a concentration of cTnI in the range of 0.10 pg/mL to 1.00 μg/mL and the detection limit was 0.0113 pg/mL under the optimal experimental conditions. With favorable performance in terms of anti-interference, stability, specificity and reproducibility, this immunosensor will provide new prospects for general PEC bioanalysis development.

Controllable signal molecule release from Au NP-gated MSNs for photocathodic detection of ultralow level AβO

By integrating a target-responsive MSN-based controlled release system with a sensitization-SPR co-enhanced thionine/MoS₂ QDs/Cu NWs photocathode, a highly sensitive split-type PEC aptasensing platform for AβO detection in blood is constructed. Ultralow detection limit (2.1 fM) and high selectivity show great potential in early AD diagnosis.

Photoelectrochemical immunoassay of interleukin-6 based on covalent reaction-triggered photocurrent polarity switching of ZnO@fullerenol

We report here a novel photocurrent polarity switching strategy for a photoelectrochemical immunoassay driven by the covalent reaction between fullerenol (COH) and chloranilic acid (CA). The sensitive detection of interleukin-6 is achieved by using CA-encapsulated liposome as the label and COH-coated ZnO as the photoactive material, with a detection limit of 1.0 fg mL^-1.

Rationally engineered high-performance BiVO4/Ag3VO4/SnS2 photoelectrodes for ultrasensitive immunosensing of CYFRA21-1 based on HRP-tyramine-triggered insoluble precipitates

A photoelectrochemical (PEC) biosensor capable of detecting cytokeratin 19 fragment 21-1 (CYFRA21-1) was optimized by taking advantage of the powerful conjugate repeats of horseradish peroxidase and tyramine (HRP-tyramine)-triggered enzymatic biocatalytic precipitation (BCP) on high-performance BiVO₄/Ag₃VO₄/SnS₂ photoelectrodes. Compared with the ubiquitous BCP strategy, we identified a design supporting conjugate repeats generated by HRP and tyramine-triggered immeasurable insoluble precipitates in the presence of hydrogen peroxide and 4-chloro-1-phenol (4-CN), and the steric hindrance improved sensitivity. Moreover, by virtue of BiVO₄, Ag₃VO₄, SnS₂ excellent level matching structure and chemical stability, a heterojunction (BiVO₄/Ag₃VO₄/SnS₂) with high light absorption efficiency has been successfully prepared. The novel heterostructure system of BiVO₄/Ag₃VO₄/SnS₂ with high detection current and low background signal exhibited high-performance PEC determination. Generally, the hitherto untapped biosensor resource realized the sensitive detection of CYFRA21-1 with a wide linear range from 50 fg/mL to 200 ng/mL, and a detection limit of 15 fg/mL, which illustrated the potential for biotechnological applications.

A new photoelectrochemical biosensor based on FeOOH and exonuclease III-aided dual recycling signal amplification for HPV-16 detection

Herein, based on iron oxyhydroxide (FeOOH) as the photoactive material and exonuclease III (exo III)-aided dual recycling signal amplification, a new photoelectrochemical (PEC) biosensor was successfully developed for human papillomavirus-16 (HPV-16) detection with a wide linear range from 0.5 fM to 1 nM and a low detection limit of 0.17 fM.

Separation of Biological Events from the Photoanode: Toward the Ferricyanide-Mediated Redox Cyclic Photoelectrochemical System of an Integrated Photoanode and Photocathode

Photoanode sensing platforms with remarkable photoelectrochemical (PEC) response and satisfying visible-light absorption have become the most promising detection systems. Nevertheless, their inevitable electrophilic character limits their expansion in the bioassay because of reductive substances in serum or other body fluids that can severely interfere with the photocurrent to be read. To solve it, a PEC platform-assembled dual-active electrode is designed to realize the separation of biological monitoring from the photoanode. The ferricyanide ([Fe(CN)₆]^3-)-mediated redox cycle is first proposed to meet the gain and loss electron requirements of the PEC system. It can avoid the self-reaction in the electrolyte caused by the addition of a traditional electron donor and acceptor, for instance, ascorbic acid and hydrogen peroxide. As a consequence, the traditional counter electrode (Pt wire) is replaced by Fe₂O₃/AgInS₂ heterojunction, which can amplify the PEC response of the cathode to meet the requirement of trace analysis. An aptasensor fabricated by the above strategies exhibits convincing data for 17β-estradiol (E2) detection from which a wide detection range is obtained in 10 fg/mL to 1 μg/mL with a detection limit of 2.74 fg/mL (S/N = 3). These advanced elements show a rosy prospect for environmental monitoring and point-of-care biomarker diagnosis.