Biosynthesis-mediated Ni-Fe-Cu LDH-to-sulfides transformation enabling sensitive detection of endogenous hydrogen sulfide with dual-readout signals

Photoelectrochemical Sensor for H2S Based on a Lead-Free Perovskite/Metal-Organic Framework Composite

Halide perovskites have emerged as a highly promising class of photoelectric materials. However, the application of lead-based perovskites has been hindered by their toxicity and relatively weak stability. In this work, a composite material comprising a lead-free perovskite cesium copper iodide (CsCu2I3) nanocrystal and a metal-organic framework (MOF-801) has been synthesized through an in situ growth approach. The resulting composite material, denoted as CsCu2I3/MOF-801, demonstrates outstanding stability and exceptional optoelectronic characteristics. MOF-801 may serve a dual role by acting as a protective barrier between CsCu2I3 nanocrystals and the external environment, as well as promoting the efficient transfer of photogenerated charge carriers, thereby mitigating their recombination. Consequently, CsCu2I3/MOF-801 demonstrates its utility by providing both stability and a notably high initial photocurrent. Leveraging the inherent reactivity between H2S and the composite material, which results in the formation of Cu2S and structural alteration, an exceptionally sensitive photoelectrochemical sensor for H2S detection has been designed. This sensor exhibits a linear detection range spanning from 0.005 to 100 μM with a remarkable detection limit of 1.67 nM, rendering it highly suitable for precise quantification of H2S in rat brains. This eco-friendly sensor significantly broadens the application horizon of perovskite materials and lays a robust foundation for their future commercialization.

Advances in electrochemical-optical dual-mode biosensors for detection of environmental pathogens

Electrochemical techniques are commonly used to analyze and screen various environmental pathogens. When used in conjunction with other optical recognition methods, it can extend the sensing range, lower the detection limit, and offer mutual validation. Nowadays, electrochemical-optical dual-mode biosensors have ensured the accuracy of test results by integrating two signals into one, indicating their potential use in primary food safety quantitative assays and screening tests. Particularly, visible optical signals from electrochemical/colorimetric dual-mode biosensors could meet the demand for real-time screening of microbial pathogens. While electrochemical-optical dual-mode probes have been receiving increasing attention, there is limited emphasis on the design approaches for sensors intended for microbial pathogens. Here, we review the recent progress in the merging of optical and electrochemical techniques, including fluorescence, colorimetry, surface plasmon resonance (SPR), and surface enhanced Raman spectroscopy (SERS). This study particularly emphasizes the reporting of various sensing performances, including sensing principles, types, cutting-edge design approaches, and applications. Finally, some concerns and upcoming advancements in dual-mode probes are briefly outlined.

New two-dimensional nanocomposites combined with target-induced strategy in an electrochemical aptasensor for sensitive determination of sulfadimethoxine

Ni-Zn bimetallic organic framework nanosheets (NiZn-MOF NSs) were modified onto PEI-functionalized MXene for the first time. The combination of the two kinds of nanosheets forms a sensing platform with superior conductivity and biocompatibility. On this basis, a highly sensitive biosensor was developed for the determination of sulfadimethoxine (SDM). Furthermore, Au and Mn nanoparticles decorated reduced graphene oxide (Au-Mn/rGO) was introduced as a signal hindering molecule under the target-induced amplification strategy. When the Au-Mn/rGO-labelled SDM-binding aptamer (Au-Mn/rGO-SBA) specifically bound to target SDM, it detached from the electrode, thereby further amplifying the electrochemical signal of [Fe(CN)6]3-/4-. The developed aptasensor for SDM showed excellent response signals in the range 1 pg mL-1 to 100 ng mL-1, with a limit of detection (LOD) as low as 0.22 pg mL-1. Significantly, the proposed sensor also showed satisfactory results in milk samples with recoveries ranging from 87.0 to 96.4% and RSD from 1.5 to 5.1%, which is believed to be useful in food safety assays.

Engineering sensitive gas sensor based on MOF-derived hollow metal-oxide semiconductor heterostructures

Metal-organic frameworks (MOFs) derived hollow heterostructured metal oxide semiconductors (MOSs) are a class of functional porous materials exhibiting distinctive physiochemical properties. Owing to the unique advantages, including large specific surface, high intrinsic catalytic performance, abundant channels for facilitating electron transfer and mass transport, and strong synergistic effect between different components, MOF-derived hollow MOSs heterostructures can work as promising candidates for gas sensing, which have thus attracted increasing attention. Aiming to provide a deep understanding on the design strategy and MOSs heterostructure, this review presents a comprehensive overview on the advantages and applications of MOF-derived hollow MOSs heterostructures when they used n for the detection of toxic gases. In addition, a deep discussion about the perspective and challenge of this interesting field is also well organized, hoping to provide guidance for the future design and development of more accurate gas sensors.