Colorimetric Determination of Chloridion in Domestic Water Based on the Wavelength Shift of CsPbBr3 Perovskite Nanocrystals via Halide Exchange

Sensing Utilities of Cesium Lead Halide Perovskites and Composites: A Comprehensive Review

Recently, the utilization of metal halide perovskites in sensing and their application in environmental studies have reached a new height. Among the different metal halide perovskites, cesium lead halide perovskites (CsPbX3; X = Cl, Br, and I) and composites have attracted great interest in sensing applications owing to their exceptional optoelectronic properties. Most CsPbX3 nanostructures and composites possess great structural stability, luminescence, and electrical properties for developing distinct optical and photonic devices. When exposed to light, heat, and water, CsPbX3 and composites can display stable sensing utilities. Many CsPbX3 and composites have been reported as probes in the detection of diverse analytes, such as metal ions, anions, important chemical species, humidity, temperature, radiation photodetection, and so forth. So far, the sensing studies of metal halide perovskites covering all metallic and organic-inorganic perovskites have already been reviewed in many studies. Nevertheless, a detailed review of the sensing utilities of CsPbX3 and composites could be helpful for researchers who are looking for innovative designs using these nanomaterials. Herein, we deliver a thorough review of the sensing utilities of CsPbX3 and composites, in the quantitation of metal ions, anions, chemicals, explosives, bioanalytes, pesticides, fungicides, cellular imaging, volatile organic compounds (VOCs), toxic gases, humidity, temperature, radiation, and photodetection. Furthermore, this review also covers the synthetic pathways, design requirements, advantages, limitations, and future directions for this material.

Double-enzyme active MnO2@BSA mediated lab-on-paper dual-modality aptasensor for di(2-ethylhexyl)phthalate

Di(2-ethylhexyl)phthalate (DEHP), as an environmental endocrine disruptor, has adverse effects on eco-environments and health. Thus, it is crucial to highly sensitive on-site detect DEHP. Herein, a double-enzyme active MnO2@BSA mediated dual-modality photoelectrochemical (PEC)/colorimetric aptasensing platform with the cascaded sensitization structures of ZnIn2S4 and TiO2 as signal generators was engineered for rapid and ultrasensitive detection of DEHP using an all-in-one lab-on-paper analytical device. Benefitting from cascaded sensitization effect, the ZnIn2S4/TiO2 photosensitive structures-assembled polypyrrole paper electrode gave an enhanced photocurrent signal. The MnO2@BSA nanoparticles (NPs) with peroxidase-mimic and oxidase-mimic double-enzymatic activity induced multiple signal quenching effects and catalyzed color development. Specifically, the MnO2@BSA NPs acted as peroxidase mimetics to generate catalytic precipitates, which not only obstructed interfacial electron transfer but also served as electron acceptors to accept photogenerated electrons. Besides, the steric hindrance effect from MnO2@BSA NPs-loaded branchy polymeric DNA duplex structures further decreased photocurrent signal. The target recycling reaction caused the detachment of MnO2@BSA NPs to increase PEC signal, realizing the ultrasensitive detection of DEHP with a low detection limit of 27 fM. Ingeniously, the freed MnO2@BSA NPs flowed to colorimetric zone with the aid of fluid channels and acted as oxidase mimetics to induce color intensity enhancement, resulting in the rapid visual detection of DEHP. This work provided a prospective paradigm to develop field-based paper analytical tool for DEHP detection in aqueous environment.

One-Step Ultrasonic Preparation of Stable Bovine Serum Albumin-Perovskite for Fluorescence Analysis of L-Ascorbic Acid and Alkaline Phosphatase

Halide lead perovskite has attracted increased attention due to its excellent optical properties. However, the poor stability of the halide lead perovskite nanocrystals has been a major obstacle to their application in biosensing. Here, we proposed a method to synthesize CsPbBr3/BSA NCs perovskite using bovine serum albumin (BSA) as a zwitterion ligand. Then, a fluorescent sensor for alkaline phosphatase determination based on CsPbBr3/BSA NCs was successfully built via the interaction of L-ascorbic acid (AA) with BSA on the perovskite surface. Under optimal conditions, the sensor showed a linear concentration range from 50 to 500 μM with a detection limit of 28 μM (signal-to-noise ratio of 3) for AA, and demonstrated a linear concentration range from 40 to 500 U/L with a detection limit of 15.5 U/L (signal-to-noise ratio of 3) for alkaline phosphatase (ALP). In addition, the proposed fluorescent biosensor exhibited good selectivity and recovery in the determination of ALP in human serum. This strategy offers an innovative way for enhancing the water stability of lead halide perovskite and promoting their application in biosensing areas.

BSA-assisted ultrasound synthesis of water stable CsPbBr3 nanocrystals for sensitive fluorescent detection of hydrogen sulfide in human serum

A bovine serum albumin (BSA)-assisted ultrasonication strategy was developed for the synthesis of CsPbBr₃ nanocrystals (NCs) with stable fluorescence properties in aqueous solution. Such a preparation method is simple, fast and does not require complex equipment. The results show that the synthesized CsPbBr₃ NCs are homogeneous in particle size and have good solubility and stability in water. The CsPbBr₃ NCs have been utilized as fluorescence probe for rapid detection of hydrogen sulfide (H₂S) in human serum. The reaction of H₂S with the lead sites on the surface of CsPbBr₃ NCs produces lead sulfide (PbS), resulting in the decrease of fluorometric intensity of CsPbBr₃ NCs. Our designed fluorescent assay has a linear S^2- detecting range of 10 ~ 800 nM with a detection limit of 7.05 nM. The assay was used to determine H₂S in human serum with spiked recoveries ranging from 94.98% to 102.69%. This work opens new avenues for the application of halide lead perovskite in different biosensing areas.

Photoelectrochemical sensors based on paper and their emerging applications in point-of-care testing

Point-of-care testing (POCT) technology is urgently required owing to the prevalence of the Internet of Things and portable electronics. In light of the attractive properties of low background and high sensitivity caused by the complete separation of excitation source and detection signal, the paper-based photoelectrochemical (PEC) sensors, featured with fast in analysis, disposable and environmental-friendly have become one of the most promising strategies in POCT. Therefore, in this review, the latest advances and principal issues in the design and fabrication of portable paper-based PEC sensors for POCT are systematically discussed. Primarily, the flexible electronic devices that can be constructed by paper and the reasons why they can be used in PEC sensors are expounded. Afterwards, the photosensitive materials involved in paper-based PEC sensor and the signal amplification strategies are emphatically introduced. Subsequently, the application of paper-based PEC sensors in medical diagnosis, environmental monitoring and food safety are further discussed. Finally, the main opportunities and challenges of paper-based PEC sensing platforms for POCT are briefly summarized. It provides a distinct perspective for researchers to construct paper-based PEC sensors with portable and cost-effective, hoping to enlighten the fast development of POCT soon after, as well as benefit human society.

A halide perovskite/lead sulfide heterostructure with enhanced photoelectrochemical performance for the sensing of alkaline phosphatase (ALP)

For the construction of halide perovskite-based photoelectrochemical (PEC) biosensors in aqueous solution, the balance between retaining the excellent photoelectric performances of the halide perovskite and the protective modification of the halide perovskite has always been a challenging problem. In this work, a simple and sensitive photoelectrochemical biosensor based on inorganic halide perovskite CsPbBr₃ as the photoactive material for the detection of alkaline phosphatase (ALP) was reported. The substrate sodium thiophosphate (Na₃SPO₃) can be catalyzed by ALP to produce hydrogen sulfide (H₂S), which can react with the lead site on the surface of the CsPbBr₃ film to form lead sulfide (PbS), resulting in a stable heterostructure and enhanced photocurrent intensity. The possible mechanism of enhanced photocurrent response of CsPbBr₃/PbS heterojunctions was studied in detail. This work paves a new way for applying halide perovskites in different biosensor designs.

Recent Progress of Perovskite Nanocrystals in Chem/Bio Sensing

Perovskite nanocrystals (PNCs) are endowed with extraordinary photophysical properties such as wide absorption spectra, high quantum yield, and narrow emission bands. However, the inherent shortcomings, especially the instability in polar solvents and water incompatibility, have hindered their application as probes in chem/bio sensing. In this review, we give a fundamental understanding of the challenges when using PNCs for chem/bio sensing and summarize recent progress in this area, including the application of PNCs in various sensors and the corresponding strategies to maintain their structural integrity. Finally, we provide perspectives to promote the future development of PNCs for chem/bio sensing applications.