H2S-based fluorescent imaging for pathophysiological processes.

Hydrogen sulfide (H2S), as an important endogenous signaling molecule, plays a vital role in many physiological processes. The abnormal behaviors of hydrogen sulfide in organisms may lead to various pathophysiological processes. Monitoring the changes in hydrogen sulfide is helpful for pre-warning and treating these pathophysiological processes. Fluorescence imaging techniques can be used to observe changes in the concentration of analytes in organisms in real-time. Therefore, employing fluorescent probes imaging to investigate the behaviors of hydrogen sulfide in pathophysiological processes is vital. This paper reviews the design strategy and sensing mechanisms of hydrogen sulfide-based fluorescent probes, focusing on imaging applications in various pathophysiological processes, including neurodegenerative diseases, inflammation, apoptosis, oxidative stress, organ injury, and diabetes. This review not only demonstrates the specific value of hydrogen sulfide fluorescent probes in preclinical studies but also illuminates the potential application in clinical diagnostics.

A novel fluorescent probe for the detection of formaldehyde in real food samples, animal serum samples and gaseous formaldehyde.

Formaldehyde (FA) is widely used as an adhesion promoter and dyeing aid in industrial production. Ingestion of a certain amount of formaldehyde may cause corrosive burns in the mouth, throat, and digestive tract. Therefore, it is very necessary to use simple and effective detection methods to ensure human health and food safety. Herein, a novel fluorescent probe NFD based on naphthalimide for the detection of formaldehyde in food was designed and synthesized. The probe had a remarkable fluorescence response to formaldehyde at 554 nm. And it exhibited fascinating advantages of good selectivity, high sensitivity, and low detection limit. In addition, the solid sensor prepared by loading the probe on the filter paper was successfully realized the visual detection of liquid and gaseous formaldehyde. More importantly, the probe possessed excellent stability in the detection of formaldehyde in real food samples and animal serum samples.

Development of a responsive probe for colorimetric and fluorescent detection of bisulfite in food and animal serum samples in 100% aqueous solution.

Bisulfite (HSO3-) has the functions of bleaching, antiseptic, antioxidant, inhibiting bacterial growth, and controlling enzymatic reactions in food. However, long-term consumption of foods containing excessive amounts of bisulfite can be harmful to health. In addition, large doses of sulfur dioxide (SO2) can cause diarrhea, hypotension, allergic and asthmatic reactions in susceptible individuals. Therefore, it is urgent and essential to explore some rapid, reliable, and convenient tools to detect HSO3- in food and SO2 gas. Herein, we exploited a fluorescent probe, NPO, to detect HSO3- in 100 % aqueous solution. The probe has the advantages of easy synthesis, excellent water solubility, significant colorimetric change, good selectivity, high sensitivity, and fast response (within 1 min). Probe NPO was successfully applied for testing strips to visualize the behavior of HSO3- and SO2 gas. Moreover, the probe has been used to monitor the behavior of HSO3- in real food samples and animal serum samples.

Modification of a nitrocellulose membrane with nanofibers for sensitivity enhancement in lateral flow test strips.

Lateral-flow analysis (LFA) is a convenient, low-cost, and rapid detection method, which has been widely used for screening of diseases. However, sensitivity enhancement in LFA is still a focus in this field and remains challenging. Herein, we propose an electrospinning coating method to modify the conventional nitrocellulose (NC) membrane and optimize the liquid flow rate for enhancing the sensitivity of the NC based LFA strips in the detection of human chorionic gonadotropin (HCG) and luteinizing hormone (LH). It can be seen that coating the NC membrane with nitrocellulose fibers could obtain a NC based strip with HCG and LH detection limits of 0.22 and 0.36 mIU mL-1 respectively, and a quantitative linear range of 0.5-500 mIU mL-1. The results show that electrospinning is effective in modifying conventional NC membranes for LFA applications.

Electrospun nitrocellulose membrane for immunochromatographic test strip with high sensitivity.

The main goal of this work is to develop an economical, portable, disposable, and reliable point of care paper biosensor based on visualization, which can be used to detect viruses, bacteria, and proteins. However, the sensitivity of immunochromatography test (ICT) strips based on nitrocellulose to target detection has always been a problem. Here, we use an electrospun nitrocellulose (ENC) fiber membrane instead of traditional nitrocellulose fiber membrane to construct ICT strips for early pregnancy detection. By proper selection of the diameter of the ENC fiber to adjust the pore size, porosity, and morphology of the membrane, ICT strips with low flow rate and high protein loading were obtained. Based on these properties, a convenient and sensitive method for the colorimetric determination of human chorionic gonadotropin was developed. Under the optimal conditions, the detection limit of ICT based on ENC membrane is 10 mIU mL-1 (S/N = 3), the linear detection range is 5-1000 mIU mL-1, and the linear relationship is Y = 0.0434 X - 0.0136 (R2 = 0.9802). In addition, the test strip has good specificity and stability, and will not produce false-positive results. Graphical abstract.

Tuning the properties of atomically precise gold nanoclusters for biolabeling and drug delivery.

A structure-determined gold-levonorgestrel nanocluster, Au10(C21H27O2)10 (Au10NC), has been obtained via solvent induced crystal transformation from Au8(C21H27O2)8 (Au8NC), accompanied by a fluorescence color change from green to yellow. A cationic polymer, poly(allylamine hydrochloride) (PAH), was chosen to assemble with Au10NC to prepare monodisperse and stable particles (Au10NC-PAH) with an increased quantum yield of 49.8%. The as-fabricated Au10NC-PAH realized effective antibody-mediated actin imaging and sustained drug release.

Atomically Precise Gold-Levonorgestrel Nanocluster as a Radiosensitizer for Enhanced Cancer Therapy.

Gold nanoclusters have become promising radiosensitizers due to their ultrasmall size and robust ability to adsorb, scatter, and re-emit radiation. However, most of the previously reported gold nanocluster radiosensitizers do not have a precise atomic structure, causing difficulties in understanding the structure-activity relationship. In this study, a structurally defined gold-levonorgestrel nanocluster consisting of Au8(C21H27O2)8 (Au8NC) with bright luminescence (58.7% quantum yield) and satisfactory biocompatibility was demonstrated as a nanoradiosensitizer. When the Au8NCs were irradiated with X-rays, they produced reactive oxygen species (ROS), resulting in irreversible cell apoptosis. As indicated by in vivo tumor formation experiments, tumorigenicity was significantly suppressed after one radiotherapy treatment with the Au8NCs. In addition, compared with tumors treated with X-rays (4 Gy) alone, tumors treated with the nanosensitizer exhibited an inhibition rate of 74.2%. This study contributes to the development of atomically precise gold nanoclusters as efficient radiosensitizers.

Atomically Precise Site-Specific Tailoring and Directional Assembly of Superatomic Silver Nanoclusters.

Convenient generation of stable superatomic silver clusters and their systematic site-specific tailoring and directional assembly present an enduring and significant challenge. In this work, we prepared a face-centered cubic (fcc) array of Ag14 superatoms protected by face-capping 1,2-dithiolate-o-carborane (C2B10H10S2) ligands, each produced from 1-thiol-o-carborane in crystallization with simultaneous reduction of Ag+ to Ag0. We find that the corner N-donor ligands contribute predominately to the stability and luminescence of the Ag14 superatom. As the first-formed nanocluster [Ag14(C2B10H10S2)6(CH3CN)8]·4CH3CN (NC-1) with labile vertex-coordinated CH3CN ligands is highly unstable, monodendate pyridine ligands were used to replace these CH3CN species site-specifically, giving [Ag14(C2B10H10S2)6(pyridine/p-methylpyridine)8] (NCs-2,3) in gram scale with its core structure intact, which features ultrastability up to 150 °C in air. Moreover, using bidentate N-containing ligands to bridge the superatomic Ag14 building blocks, we constructed an unprecedented hierarchical series of 1D-to-3D superatomic silver cluster-assembled materials (SCAM-1,2,3,4), and SCAM-4 is air-stable up to 220 °C. Furthermore, this series of stable solid-state superatomic-nanocluster materials exhibit tunable dual emission with wide-range thermochromism. The present study constitutes a major step toward the development of ligand-modulation of the structure, stability, assembly, and functionality of superatomic silver nanoclusters.