Simultaneous detection of cysteine and glutathione in food with a two-channel near-infrared fluorescent probe.

L-Cysteine (Cys) and glutathione (GSH) are closely related biological species that widely exist in food and living cells. To simultaneously detect Cys and GSH from different emission channels, we developed a fluorescent probe (BDP-NBD) based on near-infrared BODIPY and 7-nitrobenzofurazan (NBD). Upon nucleophilic substitution reaction with GSH, BDP-NBD generated an emission band at 713 nm, which can be used to determine GSH (0-100 µM) with a low detection limit (34 nM). Different from GSH, BDP-NBD underwent a nucleophilic substitution-rearrangement reaction with Cys, affording two emission bands at 550 nm and 713 nm, respectively. BDP-NBD was successfully employed to quantify Cys and GSH in various food samples with good recoveries (86.6%-104.6%). Besides, BDP-NBD can image Cys and GSH in living cells from two emission channels. Therefore, this work developed a tool for the simultaneous determination of Cys and GSH in both food and living cells so as to ensure food safety and human health.

A highly sensitive fluorescence probe for on-site detection of nerve agent mimic diethylchlorophosphonate DCP.

Nerve agents are the most toxic chemical warfare agents that pose severe threat to human health and public security. In this work, we developed a novel fluorescent probe NZNN based on naphthylimide and o-phenylenediamine to detect nerve agent mimic diethylchlorophosphonate (DCP). DCP underwent a specific nucleophilic reaction with the o-phenylenediamine group of NZNN to produce a significant fluorescence turn-on response with high selectivity, exceptional linearity, bright fluorescence, rapid response (<6 s) and a low detection limit (30.1 nM). Furthermore, a portable sensing device was fabricated for real-time detection of DCP vapor with excellent performance. This portable and sensitive device is favorable for monitoring environmental pollution and defense against chemical warfare agents.

Molecular engineering of fluorescence probe for real-time non-destructive visual screening of meat freshness.

Spoiled meat poses a great challenge to food security and human health, which should be addressed by the early monitoring and warning of the meat freshness. We herein exploited a molecular engineering strategy to construct a set of fluorescence probes (PTPY, PTAC, and PTCN) with phenothiazine as fluorophore and cyanovinyl as recognition site for the facile and efficient monitoring of meat freshness. These probes produce an obvious fluorescence color transition from dark red to bright cyan in response to cadaverine (Cad) through the nucleophilic addition/elimination reaction. The sensing performances were elaborately improved to achieve quick response (16 s), low detection limit (LOD = 3.9 nM), and high contrast fluorescence color change by enhancing the electron-withdrawing strength of cyanovinyl moiety. Furthermore, PTCN test strips were fabricated for portable and naked-eye detection of Cad vapor with fluorescence color change from crimson to cyan, and accurate determination of Cad vapor level with RGB color (red, green, blue) mode analysis. The test strips were employed to detect the freshness of real beef samples, and demonstrated a good capability of non-destructive, non-contact and visual screening meat freshness on site.

A dual-analytes responsive fluorescent probe for discriminative detection of ClO- and N2H4 in living cells.

Hydrazine (N2H4) and ClO- are very harmful for public health, hence it is important and necessary to monitor them in living cells. Herein, we rationally designed and synthesized a dual-analytes responsive fluorescent sensor PTMQ for distinguishing detection of N2H4 and ClO-. PTMQ underwent N2H4-induced double bond cleavage, affording colorimetric and green fluorescence enhancement with good selectivity and a low detection limit (89nM). On the other hand, PTMQ underwent ClO--induced sulfur oxidation and displayed red fluorescence lighting-up response towards ClO- with good selectivity, rapid response (<0.2min) and a low detection limit (58nM). Moreover, PTMQ was successfully employed for in-situ imaging of N2H4 and ClO- in living cells.

A twisted intramolecular charge transfer probe for rapid and specific detection of trace biological SO2 derivatives and bio-imaging applications.

We reported a reactive probe for HSO3(-), which showed a colorimetric and ratiometric fluorescence response to HSO3(-) with fast response (t1/2 = 20 s), good specificity and low detection limit (3.0 nM). The probe was cell membrane permeable and successfully used for visualizing trace SO2 derivatives in living cells.

Effect of orally administered hydroxypropyl chitosan on the levels of iron, copper, zinc and calcium in mice.

Two hydroxypropyl chitosan HPCS samples (HPCS1 Mw 1.6 × 10(5), HPCS2 Mw 3.5 × 10(4)) were prepared by the reaction of chitosan with propylene oxide under alkali conditions. The median lethal dose of the hydroxypropyl chitosan was greater than 10 g/kg for the laboratory mice. HPCS1 at the 0.1%, 1.0%, 1.5% and HPCS2 at the 1.0% level in diets were used to feed the mice for 90 days respectively. No pathological symptoms, clinical signs or deaths were observed for all mice. The weights of the mice in HPCS groups and control group had no significant difference. The levels of Fe, Cu, Zn and Ca in the mice were measured by atomic absorption spectrophotometry. HPCS had no significant effect on the levels of Fe, Cu, Zn and Ca in the tested mice's livers and hearts. However, hydroxypropyl chitosan at high dose exhibited inhibitory effects on the levels of Fe, Zn and Ca in some organizations.

A novel and photostable pH probe for selectively staining nuclei in living cells.

A novel pH probe based on hemi-cyanine was synthesized, which displays extremely large Stokes shift (122 nm) and good photostability. The probe responds to basic pH (pKa 8.32) with a colorimetric and fluorescence turn-on signal. Interestingly, the probe has good cell membrane permeability and could selectively stain nuclei in living cells.

Vicinal-diamine-based chiral chain dienes as ligands for rhodium(I)-catalyzed highly enantioselective conjugated additions.

A variety of readily accessible vicinal-diamine-based chiral chain dienes were successfully synthesized and utilized as steering ligands for rhodium-catalyzed conjugated additions of organoboronic acids to α,ß-unsaturated carbonyl compounds to afford the desired adducts in good to excellent yields and ee's.

Simple chiral chain dienes as ligands for Rh(I)-catalyzed conjugated additions.

This paper describes that a simple and readily available chain diene (3R,4R)-hexa-1,5-diene-3,4-diol (L1) was successfully utilized as a novel steering ligand for Rh(I)-catalyzed asymmetric conjugated additions. Encouraging yields and ee's have been achieved, which may provide a new and practical direction for designing chiral diene ligands in the future.

CuI-catalyzed suzuki-miyaura and sonogashira cross-coupling reactions using DABCO as ligand.

In the presence of TBAB, CuI-catalyzed Suzuki-Miyaura cross-coupling of vinyl halides and aryl halides with arylboronic acids was conducted smoothly to afford the corresponding diarylethenes and polyaryls in moderate to good yields using DABCO (1,4-diazabicyclo[2.2.2]octane) as the ligand. We also found that the inexpensive CuI/DABCO catalytic system was effective for Sonogashira cross-couplings of aryl halides and vinyl halides. A variety of aryl halides and vinyl halides including activated aryl chlorides underwent the coupling with terminal alkynes in moderate to excellent yields.