An Antifouling Photoelectrochemical Ultramicrosensor for Unbiased Single‐Cell Analysis

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.

A responsive organic probe based photoelectrochemical sensor for hydrazine detection

This study developed a new photoelectrochemical (PEC) sensor for the detection of the hydrazine (N2H4, HZ) based on a donor-π-bridge-acceptor (D-π-A) configuration organic photoactive dye (Dye-HZ). The dye was covalently immobilized on an FTO/TiO2 (FTO: fluorine-doped tin oxide) substrate, resulting in a photoanode FTO/TiO2/Dye-HZ that exhibits a specific PEC response to N2H4. Hydrazine reacts with the acetyl group in the Dye-HZ molecule, leading to its removal and the formation of a hydroxy group. The hydroxy group dissociates a hydrogen ion, forming a phenoxide anion with strong electron-donating characteristics. As a result, the dye molecule exhibits a strong intramolecular charge transfer effect, significantly enhancing absorbance and photoelectric response under visible light irradiation, leading to a remarkable increase in photocurrent and enabling highly sensitive detection of hydrazine. Furthermore, the PEC sensor demonstrates excellent selectivity and can be applied for the detection of hydrazine in real water samples. This study presents an innovative PEC sensing approach for hydrazine based on responsive photoactive molecules, providing new insights for PEC detection of other environmental pollutants.

Zwitterionic Polymers Coating Antibiofouling Photoelectrochemical Aptasensor for In Vivo Antibiotic Metabolism Monitoring and Tracking

Long-term in vivo monitoring and tracking of target molecules in living organism is essential to reveal vital physiological activity. However, undesirable contamination of protein and biological cells may bring serious biofouling issues. Herein, zwitterionic sulfobetaine methacrylate (SBMA) polymers are grafted on the TiO₂ nanotube (NT) surface with polydopamine (PDA) as linker to fabricate a TiO₂ NTs/PDA/SBMA photoelectrode. The TiO₂ NTs/PDA/SBMA/aptamer-based PEC aptasensor can be sensitive and have selective detection of target molecules with excellent antibiofouling activity. Beneficial from the above advantages, the implantable micro-PEC aptasensor has implemented in vivo tracking and monitoring of the metabolism of antibiotics in a living mouse. The robust antibiofouling property generates new inquiries and an approach for long-standing questions in a new way for reliable and long-term sensing of vital biomolecules in complex biological fluids and uncovers a promising advance of intrinsic physiological mechanisms.

A Laser-Induced Photoelectrochemical Sensor for Natural Sweat Cu2+ Detection

Tracking fluctuations in the Cu2+ level in sweat is meaningful for non-invasive and real-time assessment of Cu2+-abnormality-related diseases and provides important diagnostic information. However, the user-unfriendly ways to obtain sweat and sweat biofouling have limited the development of this field. Herein, we exploit a highly sensitive photoelectrochemical (PEC) sensor as a detection method, a powerful laser engraving technique for the large-scale fabrication of laser-induced graphene and In-doped CdS (LIG-In-CdS) photoelectrodes, and a hydrophilic porous polyvinyl alcohol (PVA) hydrogel for natural sweat collection for fingertip touch sweat Cu2+ monitoring. The proposed sensor has several very attractive features: (i) the LIG-In-CdS photoelectrode with high photoelectric conversion efficiency can be produced by a cheap 450 nm semiconductor laser system; (ii) the sensor performs Cu2+ detection with a wide linear range of 1.28 ng/mL~5.12 μg/mL and good selectivity; (iii) the PVA hydrogel possesses an excellent antifouling effect ability and a rapid natural sweat collection ability; and (iv) the sensor exhibits feasibility and good reliability for PEC sensing of sweat Cu2+. Thus, these advantages endow the proposed method with a great deal of potential for smart monitoring of heavy metals in sweat in the future.