New colorimetric and fluorometric chemosensor for selective Hg2+ sensing in a near-perfect aqueous solution and bio-imaging.

We report a new 7-nitrobenzo-2-oxa-1, 3-diazolyl (NBD)-based chemosensor containing a piperazine derivative, NBDP, for detection of mercury ions in almost 100% aqueous medium. The chemosensor shows sensing exclusively toward Hg2+ with a switch-on fluorescence response at 543 nm, which could be attributed to the blocking of PET (photo-induced electron transfer) process upon complexation with mercury ions. The molar ratio of Hg(Ⅱ) to NBDP in the complex is 1:1 based on the Job's plot and HRMS studies. Optimized configurations of NBDP and NBDP-Hg2+ complexes were simulated by means of DFT calculations. The reversible fluorescence response with low detection limit (19.2 nM) in the pH range of 6.0-7.5 renders NBDP a promising candidate for Hg2+ detection in neutral aqueous environments. For the practical application of the chemosensor, test strips were successfully fabricated for rapid detection of Hg2+ ions. Moreover, the utility of NBDP showing the mercury recognition in Human liver cancer cells (SMMC-7721) and zebrafish as well as in live tissues of Arabidopsis thaliana has been demonstrated as monitored by fluorescence imaging.

A new colorimetric and ratiometric fluorescent probe for selective recognition of cyanide in aqueous media.

A simple naphthopyran derivative (L) has been synthesized as a colorimetric and ratiometric fluorescent probe for cyanide sensing in the aqueous DMSO medium and paper strips. The nucleophilic addition of CN- to this probe blocks the π-conjugation and the intramolecular charge transfer (ICT) transition between naphthopyran and benzoindolium moieties and consequently results in remarkable color and spectral changes. Upon addition of cyanide, L displayed a ratiometric fluorescence response with a blue shift of the peak position and a noticeable color change from fuchsia to colorless within 90s. The probe exhibits high selectivity and sensitivity toward CN- over other anions and the detection limit was calculated to be 7.56×10-7M, which is well below the WHO cyanide standard in drinking water (1.9µM). In addition, the excitation and emission of the probe were within the visible wavelength range, which could benefit an application of the probe in an inexpensive portable cyanide sensor. The sensing ability of L has been successfully applied in real water samples. Furthermore, test strips based on L were fabricated, which can act as convenient and efficient test kits for detecting CN-.

Dexmedetomidine mitigates sevoflurane-induced cell cycle arrest in hippocampus.

BACKGROUND: Epidemiologic studies suggest the possibility of a modestly elevated risk of adverse neurodevelopmental outcomes in children exposed to anesthesia during early childhood. Sevoflurane is widely used in pediatric anesthetic practice because of its rapid induction and lower pungency. However, it is reported that sevoflurane leads to the long-term cognitive impairment. Some evidence revealed that the selective α2-adrenoreceptor agonist dexmedetomidine (DEX) exerts neuroprotective effects in various brain injury models of animals. But the role of DEX on sevoflurane-induced neuro-damage remains elusive. MATERIALS AND METHODS: In our study, we isolated the hippocampal neuron cells from newborn neonatal rats and verified the purity of neurons by immunocytochemistry. We employed the flow cytometry and western blot to examine the effect of sevoflurane, DEX and α2-adrenergic receptor antagonist yohimbine on cell cycle distribution. RESULTS: Immunocytochemistry results showed the purity of neurons > 94%, which provided a good model for neural pharmacology experiments. The exposure of sevoflurane-induced cell cycle arrest at S phase and suppressed the expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB). The addition of DEX suppressed sevoflurane-induced cell cycle arrest and the inhibitory of BDNF and TrkB expression. But the function of DEX was partly blocked by a α2 adrenergic receptor blocker yohimbine. CONCLUSION: Sevoflurane suppressed neuron cell proliferation via inhibiting the expression of BDNF and TrkB, and DEX relieved the neurotoxicity induced by sevoflurane via α2 adrenergic receptor. These findings provided new evidence that DEX exerted as a neuroprotective strategy in sevoflurane-induced neuro-damage, and provided new basis for the clinical application of DEX.

[Indirect determination of Vc with flame atomic absorption spectrometry].

In the present paper, a new method for indirect determination of Vc by atomic absorption spectrometry is proposed, based on the reducing properties of Ag+. The effects of temperature, reaction time and use level of Ag+ on the experiment were studied. Room-temperature and reaction time of 35 minutes were chosen. The oxidant amount is 2.0 mL solution of Ag+ (1.0 microg mL(-1)). Meanwhile the AAS working conditions for Ag determination were optimized. The proposed method allows the determination of Vc in a wide range with a relative standard deviation of 2.04%, and the detection limit is less than 1 microg x mL(-1). The method cannot be disturbed by the colour of sample. The interference of coexistent substance is also weak. Other methods for determining Vc could be remedied by this method. Two kinds of standard curves were plotted, standard working curve of sliver and standard working curve of Vc. The former is easier, while the latter is more accurate and could be applied flexibly according to the physical circumstances. This method is easy to control and has been applied to the determination of ascorbic acid in pharmaceutical preparations and orange juice. The recovery ratio of this method is 99.30%-106.06%. The results obtained in the analysis agreed well with the iodimetry in pharmacopeia.