as about 90% of the initial recovery after the sorbent usage for three times; therefore, the Fe3O4/Cu CuO/GO-NC can readily be regenerated.Protein-encapsulated gold nanoclusters (Au NCs) have recently gained much attention in biosensing and bioimaging applications owing to their remarkable fluorescence properties, nontoxicity and good biocompatibility. In this work, the mannose was grafted onto the bovine serum albumin (BSA) encapsulated Au NCs (BSA-Au NCs) to produce a mannose functionalized BSA-Au NCs (Man-BSA-Au NCs) as a new fluorescence probe for Concanavalin A (Con A) detection and human breast cancer cell imaging. A new strategy with mannose-BSA conjugates as template was firstly applied for the synthesis of Man-BSA-Au NCs, leading to a high loading of mannose (767.6 ± 7.2 mg/L) onto BSA-Au NCs. The as-prepared Man-BSA-Au NCs showed advantages of facile preparation, good monodispersity and strong red-emission. Notably, aggregation-induced fluorescence quenching of Man-BSA-Au NCs was triggered by Con A due to the multivalent cooperative interactions between mannose and Con A, which was subsequently confirmed by MALDI-TOF MS. Hence highly selective and sensitive fluorescence detection of Con A was achieved by using Man-BSA-Au NCs as a fluorescence sensor. A good linear relationship was obtained over the range of 0.01-1 μM (R2 = 0.994) with a detection limit of 0.62 nM (S/N = 3). The developed sensor was then applied to determine Con A in human serum with acceptable recoveries of 93.70-104.8%. Moreover, based on the specific recognition between mannose and overexpressed mannose receptors on human breast cancer cells, the Man-BSA-Au NCs were successfully utilized for cancer cell imaging with good specificity.A new procedure is proposed for the determination of metal contaminants (Cr, Fe, Mg, Mn, Na and Ni) in polymeric diphenylmethane diisocyanate (PMDI), a raw material used to produce polyurethane polymers. The feasibility of using Zeeman-effect background correction graphite furnace atomic absorption spectrometry (GF AAS) and direct sampling (DS) was evaluated. Calibration using aqueous standard solutions was feasible and chemical modifiers as well as reference materials for this purpose were unnecessary. Relatively high sample masses (up to 23 mg) were used allowing very low limits of detection ranging from 0.06 ng g-1 to 1 ng g-1 (Fe and Mg) up to 3 ng g-1 (Ni), with relative standard deviation lower than 15%. The following parameters were evaluated pyrolysis and atomization temperatures , sample mass, as well as the use of low sensitivity conditions (Zeeman effect background correction magnetic field strength adjustment and the use of a secondary wavelength for Fe and Na determinations, respectively).  https://www.selleckchem.com/products/gne-049.html  Results were compared with those obtained by microwave-assisted digestion and microwave-induced combustion with subsequent analytes determination by inductively coupled plasma optical emission spectrometry (ICP-OES) and by inductively coupled plasma mass spectrometry (ICP-MS). No significant difference was observed between the results obtained by DS-GF AAS, ICP-MS and ICP-OES after both digestion systems. The proposed DS-GF AAS method allowed the determination of six elements in PMDI (which is considered as a complex matrix) with limits of detection lower than those achieved by other methods. This new procedure can be used as quality control of polyurethanes industry for ultra-trace inorganic impurities.A novel and sensitive method for the selective determination of Cr(VI) and non-chromatographic speciation of Cr(VI) and Cr(III) was developed based on chemical vapor generation (CVG) in KBH4-acid system for sample introduction into an inductively coupled plasma mass spectrometer (ICP-MS) for detection. The CVG of Cr(VI), rather than Cr(III), was found to be remarkably enhanced in the presence of sodium diethylaminodithioformate (DDTC). After the oxidation of Cr(III) to Cr(VI) by KMnO4, the quantitation of Cr(III) could be obtained based on the difference between the concentration of total chromium and that of Cr(VI). Parameters affecting the CVG reaction and determination of Cr(VI) were evaluated in detail, including the concentrations of DDTC, hydrochloric acid and KBH4, the sample flow rate, as well as the length of reaction and transferring tubing. Under optimal conditions, the CVG efficiency and the limit of detection (LOD) of Cr(VI) were found to be 28% and 0.2 ng mL-1, respectively. The relative standard deviations for seven replicate measurements of 20 ng mL-1 of Cr(Ⅵ) was 1.8%. Furthermore, with excess DDTC (100 μg mL-1) added to the test solutions, possible interferences from Cu2+ (up to 400 ng mL-1) could be eliminated. The proposed method was thus successfully applied to the determination of Cr(VI) in three real water samples and one certified reference water sample, as well as two simulated water samples of Cr(VI) and Cr(III), all with satisfactory results. The possible reasons were discussed for the varied degrees of enhancement between Cr(III) and Cr(VI).Although biothiols, including cysteine (Cys), glutathione (GSH), and homocysteine (Hcy) can be used to diagnose many diseases and research physiological metabolism in many physiological processes, in situ real-time detection and differentiation of biothiols is still challenging because their similar chemical properties and molecular structures. Herein, we utilized the native chemical ligation (NCL) reaction mechanism to develop a Förster resonance energy transfer (FRET) strategy for designing a cell penetration peptide TAT-modified ratiometric two-photon biothiols probe (TAT-probe). The TAT-probe can not only rapidly enter into mitochondria assisted by TAT peptide, but also simultaneously detect biothiols and sequentially distinguish GSH. When the TAT-probe was excited with 404/820 nm wavelength light, it showed a change in the ratio of fluorescence after adding biothiols, including a quenched red fluorescence intensity (λem = 585 nm) and an enhanced signal in green fluorescence intensity (λem = 520 nm). Excitingly, the TAT-probe excited at 545 nm could display a red fluorescence (λem = 585 nm) towards GSH and a quenched signal towards Hcy or Cys. This specific fluorescence response indicated the TAT-probe could effectively detect biothiols and differentiate GSH from Cys/Hcy in mitochondria. This work pioneered a new approach to design and synthesize biothiol-probes based on peptides and NCL reaction mechanism.