NO donors are routinely used as the exogenous source in in vitro studies. However, the kinetics or the dose of NO release from the existing donors is not readily monitored. This complicates the elucidation of the involvement of NO in a biological response. We report herein a series of NO donors (NOD545a–g), whose NO release is triggered by UV light at 365 nm or a two-photon laser at 740 nm, and importantly, their NO release is accompanied by a drastic fluorescence turn-on, which has been harnessed to follow the kinetics and dose of NO release in a real-time fashion with spectroscopic methods or microscopic methods in in vitro studies. These merits have rendered NOD545a–g useful molecular tools in NO biology.

Development of a molecular probe for selective detection of MeHg+ in the presence of Hg2+ is a mission impossible to accomplish. Speciation analysis of two substrates with a single kinetic trace exploiting their differential reactivity toward a single probe, i.e., multiplexing in the time domain, is a cost-effective and powerful alternative. We have developed such a probe (Hg410) for simultaneously quantification of Hg2+ and MeHg+ in aqueous media. Hg410 is designed via the “covalent-assembly” approach, displays a zero background, and bears a very concise molecular construct. It has harnessed proximity-based catalysis to achieve high reactivity toward Hg2+ and MeHg+. An unprecedentedly low detection limit of ca. 4.6 pM and 160 pM was measured for Hg2+ and MeHg+, respectively.

We herein report a novel fluorescent probe for Hg2+ based on the deprotection of 1,3-dithiolane, via the covalent assembly principle. Presence of Hg2+ triggers a cascade, which ultimately furnishes the push–pull backbone of a fluorescent dye, rendering a turn-on signal from a zero background and hence high detection sensitivity.

On the basis of the structure of heterocyclic-fused cis configuration derivatives and chain-opening neonicotinoids, two series of novel chain-opening tetrahydropyridine analogues were designed and synthesized. The preliminary bioassay tests were determined on cowpea aphid (Aphis craccivora) and armyworm (Pseudaletia separata Walker). The results showed that some of the target compounds exhibited repellent effects, whereas others showed good insecticidal activities.

•Fipronil induced cell death in Drosophila S2 cells through apoptotic pathways in a dose- and time-dependent manner.•The depolarization of mitochondrial membrane potential and increase of ROS were contributed to the apoptosis of S2 cells.•Apoptotic proteins Bcl-2, DIAP1, Cyt c and caspase were changed in the S2 cells.Fipronil is the first phenylpyrazole insecticide widely used in controlling pests, including pyrethroid, organophosphate and carbamate insecticides. It is generally accepted that fipronil elicits neurotoxicity via interactions with GABA and glutamate receptors, although alternative mechanisms have recently been proposed. This study evaluates the genotoxicity of fipronil and its likely mode of action in Drosophila S2 cells, as an in vitro model. Fipronil administrated the concentration- and time-dependent S2 cell proliferation. Intracellular biochemical assays showed that fipronil-induced S2 cell apoptosis coincided with a decrease in the mitochondrial membrane potential and an increase reactive oxygen species generation, a significant decrease of Bcl-2 and DIAP1, and a marked augmentation of Cyt c and caspase-3. Because caspase-3 is the major executioner caspase downstream of caspase-9 in Drosophila, enzyme activity assays were used to determine the activities of caspase-3 and caspase-9. Our results indicated that fipronil effectively induced apoptosis in Drosophila S2 cells through caspase-dependent mitochondrial pathways.Download full-size image

We herein report a novel fluorescent probe for Hg2+ based on the deprotection of 1,3-dithiolane, via the covalent assembly principle. Presence of Hg2+ triggers a cascade, which ultimately furnishes the push–pull backbone of a fluorescent dye, rendering a turn-on signal from a zero background and hence high detection sensitivity.