Insights into self-degradation of cysteine esters and amides under physiological conditions yield new cleavable chemistry.

An unprecedented HS release from cysteine esters and amides (CysO/NHR) under physiological conditions was discovered and the plausible mechanism was proposed. Alkylation of the amino moiety of cysteine esters enables the HS release to be tuned and further provides support to the mechanistic insights. This discovery not only provides new insights into several fundamental science issues including non-enzymatic HS-produced pathways, but also inspires new tunable cleavable motifs for sustained release of arylthiols and even for prodrug design.

Rational design of a dual-reactive probe for imaging the biogenesis of both HS and GSH from l-Cys rather than d-Cys in live cells.

Biothiols and their interconversion are involved in cellular redox homeostasis as well as many physiological processes. Here, a dual-reactive dual-quenching fluorescent probe was rationally developed based on thiolysis reactions of 7-nitrobenzoxadiazole (NBD) tertiary amine and 7-cyanobenzoxadiazole (CBD) arylether for imaging of the biothiol interconversion. We demonstrate that the NBD-CBD probe exhibits very weak background fluorescence due to the dual-quenching effects, and can be dual-activated by HS and GSH with an over 500-fold fluorescence increase at 525 nm.

DBSCAN Spatial Clustering Analysis of Urban "Production-Living-Ecological" Space Based on POI Data: A Case Study of Central Urban Wuhan, China.

As urban spatial patterns are the prerequisite and foundation of urban planning, spatial pattern research will enable its improvement. The formation mechanism and definition of an urban "production-living-ecological" space is used here to construct a classification system for POI (points of interests) data, crawl POI data in Python, and DBSCAN (density-based spatial clustering of application with noise) to perform cluster analysis. This mechanism helps to determine the cluster density and to study the overall and component spatial patterns of the "production-living-ecological" space in the central urban area of Wuhan.

Cell-Trappable BODIPY-NBD Dyad for Imaging of Basal and Stress-Induced HS in Live Biosystems.

HS is a gaseous signaling molecule that is involved in many physiological and pathological processes. In general, the level of intracellular HS (<1 μM) is much lower than that of GSH (∼1-10 mM), leading to the remaining challenge of selective detection and differentiation of endogenous HS in live biosystems. To this end, we quantitatively demonstrate that the thiolysis of NBD amine has much higher selectivity for HS over GSH than that of the reduction of aryl azide.

Thiolysis of CBD arylethers for development of highly GSH-selective fluorescent probes.

Thiolysis of 7-cyanobenzoxadiazole (CBD) arylether was investigated for development of GSH-selective fluorescent probes for the first time. The results demonstrate that CBD-based probes have tunable reactivities and appropriate dissociation constants for GSH, and are highly GSH-selective and suitable for bioimaging.

Investigation of thiolysis of 4-substituted SBD derivatives and rational design of a GSH-selective fluorescent probe.

In order to evaluate 7-sulfonamide benzoxadiazole (SBD) derivatives for the development of fluorescent probes, herein we investigated the thiolysis reactivity and selectivity of a series of SBD compounds with different atoms (N/O/S/Se) at the 4-position. Both SBD-amine and SBD-ether are stable toward biothiols in buffer (pH 7.4), while SBD-selenoether can react efficiently with biothiols GSH/Hcy, Cys, and H2S to produce SBD-SG/S-Hcy, SBD-NH-Cys, and SBD-SH, respectively, with three different sets of spectral signals.

A H S-Specific Ultrasensitive Fluorogenic Probe Reveals TMV-Induced H S Production to Limit Virus Replication.

Understanding the role of H S in host defense mechanisms against RNA viruses may provide opportunities for the development of antivirals to combat viral infections. Here, we have developed a green-emitting fluorogenic probe, which exhibits a large fluorescence response at 520 nm (>560-fold) when treated with 100 μM H S for 1 h. It is highly selective for H S over biothiols (>400-fold F/F ) and has a detection limit of 12.