A catalyst consisting of single-atom Ru sites supported on an N-MXene (Ti ₃ C ₂ T x ) was developed for pH-universal hydrogen generation based on theoretical predictions, whose performances are comparable to and better than those of Pt/C.

We report the development of a red-emitting fluorescence probe (XDS) for hydrogen sulfide (H₂S) detection in biosystems, real-world food samples, and application of this probe for monitoring of H₂S production during food spoilage. The XDS probe is developed by coupling of coumarin derivative to rhodanic-CN through a H₂S responsive CC bond. Remarkable fluorescence quenching of XDS is observed as a result of the response to H₂S. Semi-quantitative detection of H₂S in three real-world water and two beer samples and monitoring of H₂S production during food spoilage in real-time by "naked-eye" and smartphone colorimetric analysis are then achieved using XDS as the probe. Moreover, XDS is low toxicity, allowing it being used for visualizing endogenous and exogenous H₂S in vivo in a mouse model. It is expected that the successful development of XDS could provide an effective tool for investigating the roles of H₂S in biomedical system and for future food safety evaluation.

Chemosensors play important roles in cation and anion recognition in biological, industrial, and environmental processes. Although many efforts have been made to develop artificial fluorescent receptors for Cu²⁺ and S²⁻, their applications in the detection in bulk solutions are limited. In this work, we report a novel fluorescence chemosensor (NL) based on the 7-nitrobenz-2-oxa-1,3-diazole (NBD) fluorophore for the quantification of Cu²⁺ and S²⁻ in single intact cells. NL specifically binds to Cu²⁺ in the presence of other competing cations, and evident changes in UV-vis and fluorescence spectra in HEPES buffer are noticed. Based on the displacement approach, the selective sense S²⁻ with the in situ generated NL-Cu²⁺ ensemble gives a remarkable recovery of fluorescence and UV-vis absorption spectra. The detection limits of NL for Cu²⁺ and NL-Cu²⁺ for S²⁻ were estimated to be 1.6 nM and 0.17 μM, respectively. NL and the resultant complex NL-Cu²⁺ exhibit low cytotoxicity and cell-membrane permeability, which makes them capable of Cu²⁺ and S²⁻ imaging and quantification in living MDA-MB-231 cells.

Emission of toxic gaseous sulfur dioxide (SO₂) and its derivative bisulfite (HSO₃^-) from various industrial applications, like food processing, transportation, and the coking process, has raised substantial concerns regarding environmental quality and public health. The probes for specific and sensitive detection of SO₂ derivatives plays an essential role in their regulation, and ultimately mitigating their environmental and health implications, but the one that can detect SO₂ derivatives onsite by end users remains limited. Herein, we report a new near-infrared fluorescence probe (SL) for rapid and onsite detection of SO₂ derivative, HSO₃^- in industrial wastewater, food samples and for sensing its interaction with biological organisms. The SL is developed through coupling of quinolinium and coumarin moiety through an electron deficit CC bond that can specifically react with HSO₃^- via a Michael addition. By recording the blue shift of absorption and emission spectra, SL can sensitively detect HSO₃^- (limit of detection, 38 nM) in aqueous solution within 40 s SL is biocompatible, can be used for evaluating toxicity of SO₂ derivatives in living organisms. The preparation of SL-stained test paper allows the colorimetric/fluorometric analysis for quantification of HSO₃^- onsite in food, river and coking wastewater samples using a smartphone. The successful development of SL not only provides a new tool to investigate HSO₃^- in biological, food and environmental systems, but also potentially promotes the application of fluorescence technique for rapid and onsite analysis of real-world samples by end users.