Latest ArticlesThe synthesis of α-ZrP with a range of crystallinity is of high importance due to the different requirements in various applications. Nanosized crystalline α-ZrP is typically obtained by refluxing amorphous ZrP in concentrated H3PO4 solutions. Microcrystalline α-ZrP are obtained by direct precipitation in the presence of either HF or oxalic acid which are used as complexing agents for zirconium. These larger crystals are useful as ion-exchangers in column-type applications as the back pressure can be significantly reduced. A novel minimalistic synthesis that is green, simple and fast is highlighted in this review. Both nano-sized and micro-sized α-ZrP can be prepared via this protocol to meet many potential applications. Applications of α-ZrP in ion-exchange, catalysis, lubricants, intercalation hosts, polymer fillers and fire retardants are discussed.
The acetyl ester plays an important role for protection of the hydroxyl groups in carbohydrates synthesis. In the present study, we described an efficient deprotection of acetyl group of pentacyclic triterpenoid by using methanolic ammonia in THF solution. Good selectivity for cleaving gal-C2-OAc group of 3β-hydroxy-olean-12-en-28-oic acid 28-N-2, 3, 4, 6-tetra-O-acetyl-β-D-galactopyranoside (3) was achieved in the presence of methanolic ammonia within 4 h at low temperature (-60℃) in a yield of 56%. The reaction disclosed here provides a new method for the synthesis of C2 selective modified carbohydrates, which is more useful than conventional synthesis procedure that usually requires many steps including temporary regioselective protection and deprotection. When the reaction temperature was increased from -60℃ to room temperature, the cleavage of the other three acetyl groups of galactose in an order of C4-OAc > C3-OAc > C6-OAc was observed. Based on this study, a plausible route for the deacetylation reaction has been proposed.
Thiophonate-methyl (TPM) is one of fungicides and pesticides widely used in agriculture field. However, the residue of its benzimidazole (BZD) metabolites in related agricultural products poses a potential risk to consumers. In this paper, nickel oxide nanoparticle-deposited silica (SiO2@NiO) composite was used for the selective enrichment and purification of TPM's BZD metabolites in celery cabbage sprayed with TPM. Meanwhile, high-performance liquid chromatography coupled with precursor ion scan-mass spectrometry (HPLC-PIS-MS) and high-resolution MS/MS analysis (HR-MS/MS) was utilized for their qualitative and quantitative analysis. Twenty-one potential TPM's BZD metabolites were found and four of them were identified. One metabolite was discovered for the first time. Besides, a robust and sensitive quantitative method was developed with good linearities (R2 > 0.9972) within a wide range of 10.00-1000 ng/g. The detection limits of three known TPM's metabolites were within the range of 3.20-4.90 ng/g. Relative standard deviations (RSDs) of intra-day and inter-day precisions were less than 18.3%, which showed perfect reproducibility. The method was successfully applied to monitoring TPM's BZD metabolites in celery cabbage sprayed with TPM and the concentration versus time curves of TPM's metabolites in celery cabbage were plotted. This method is expected to be used to monitor BZD residues in various fruits and vegetables.
A novel donor-acceptor (D-A) type of two-photon (TP) fluorescent probe, i.e. Lyso-OSC, based on the lysosome-targeting morpholine group was developed. The polarity sensing coumarin group was functionalized as the acceptor and the 1-vinyl-4-methoxybenzene group was engineered as the donor. The fluorescence intensity and emission maximum wavelength of Lyso-OSC are highly sensitive to the polarity changes of solvent. The two-photon absorption cross-section and tissue penetration depth are up to 254 GM and 150 μm, respectively. The strong fluorescence, high sensitivity to polarity, low cytotoxicity, and accurate lysosome-targeting ability entail Lyso-OSC the excellent performance in detecting the polarity changes of cellular environment. To this end, a bright, real-time imaging autophagy of living cells has been achieved.
Ribonucleotides are usually functioned as biomarkers to diagnose diseases and monitor the life activities in living organisms, and their discrimination is of great significance but challenging. Taking advantage of the unique characteristics of gold nanorods (AuNRs), herein, a colorimetric sensor array for discrimination of twelve ribonucleotides was developed based on the chemical etching of AuNRs with controllable aspect ratios. During the etching process, AuNRs were preferentially shortened and eventually turned into Au(Ⅲ) state by Fenton's reaction. The morphological change of AuNRs led to the significant color change and blue shift in the corresponding extinction spectrum. However, when Fe2+ bound with ribonucleotides, the Fenton's reaction was prevented and the ability to etch AuNRs was weakened or disappeared. Due to the different structures of nucleotides, the binding ability of them with Fe2+ was distinct, resulting in the discrepancy in the chemical etching of AuNRs, which could be developed for distinguishing ribonucleotides. Moreover, the proposed sensor array was successfully explored to distinguish ribonucleotides in complex human urine samples.
Organocatalysis represents a promising field in chemical fixation of CO2. Herein, a facile metal-free strategy was reported for the one-pot preparation of cyclic carbonates and α-hydroxy ketones from vicinal diols, propargylic alcohols and CO2. Wide scope of vicinal diols and propargylic alcohols was demonstrated to be efficient under the DBU-catalyzed conditions. A plausible mechanism was proposed, which included detailed main and side reactions under the metal-free conditions.
Four new seco-dibenzocyclooctadiene lignans, kadlongilignans A-D (1-4), consisting of a rare 6, 7-seco-(1), two 15, 16-seco-(2 and 3) and a 9, 10-seco-dibenzocyclooctadiene (4) lignans, were isolated from the roots of Kadsura longipedunculata. Their structures were elucidated by spectroscopic analysis, including extensive NMR, MS and ECD (electronic circular dichroism) spectra. Compounds 3 and 4 exhibited potent inhibitory activities against NO (nitric oxide) production of LPS (lipopolysaccharide)-induced murine macrophages with the inhibition rates of 36.3% and 26.9%, respectively.
Aggregation-induced emission (AIE) active photochromic molecules have attracted growing attention for their versatile applications. Here we designed and synthesized five newly unsymmetrical photochromic diarylethene (DAE) dyads (BTE1-5) by connecting tetraphenylethene (TPE) and aromatic substituent via bithienylethene (BTE) bridge. The chemical structures of those compounds were identified by 1H NMR, 13C NMR and HRMS.The absorption and emission of these dyads were investigated by UV-vis and fluorescence spectroscopy, respectively. The results showed that all those compounds exhibited typically AIE or aggregation-induced emission enhancement (AIEE) characteristic. Particularly, when an aggregation caused quenching (ACQ) fluorophore (triphenylamine) was grafted to the molecule, connecting with TPE via BTE-bridge, the ACQ phenomenon was dissipated and converted to an AIE luminophore, and those compounds exhibited photochromism upon irradiation with alternative UV and visible light. The solution or solid of those compounds showed distinctly fluorescence switching "ON" or "OFF" observation upon irradiation with alternative UV and visible light.It is interesting that BTE1 could be applied in recording and rewritable information storage, and the cyclization quantum yields could be affected by substituent significantly.
A simple and feasible potentiometric immunosensing platform based on enzymatic biocatalytic precipitation technique was designed for the sensitive detection of thyroid-stimulating hormone (TSH; a typical kind of biomarkers for thyroid carcinoma), using horseradish peroxidase (HRP)-loaded liposome for the signal amplification. To construct such an assay system, a sandwich-type immunoreaction was readily carried out on monoclonal anti-TSH capture antibody-coated electrode by using polyclonal antiTSH secondary antibody-conjugated HRP-loaded liposome. Accompanying the formation of sandwichtype immunocomplex, the carried liposome was lysed through the added Triton X-100 to release the entrapped HRP molecules, which catalyzed the oxidation of 4-chloro-1-naphthol to produce an insoluble and uncharged organic precipitation on the electrode surface, thereby causing the change of the local electrical potential. Two labeling protocols with and without the liposome were investigated for detection of target TSH, improved analytical features were achieved with HRP-entrapped liposome. Under optimal conditions, the potentiometric immunosensor had good responses for TSH detection within the linear range of 0.01-30 μIU/mL at a detection limit of 0.0067 μIU/mL. Good reproducibility, high specificity and long-time stability were acquired during the assay procedure. Importantly, a wellmatched accuracy between the potentiometric immunosensor and commercial human TSH ELISA kit was gave for the analysis of human serum samples.
Carbon dots (CDs) with multi-color emissive properties and a high photoluminescent quantum yield (PLQY) have attracted great attention recently due to their potential applications in chemical, environmental, biological and photo-electronic fields. Solvent-dependent effect in photoluminescence provides a facial and effective approach to tune the emission of CDs. In this study, green emissive nitrogen-doped carbon dots (N-CDs) are synthesized from p-hydroquinone and ethylenediamine through a simple hydrothermal method. The as-prepared N-CDs possess a robust excitation-independent green luminescence and a high PLQYof up to 15.9%. Further spectroscopic characterization indicates that the high PLQY is achieved by the balance of nitrogen doping states and the surface passivation extent in CDs. The N-CDs also exhibit solvent-dependent multi-color emissive property and distinct PLQY in different solvents (the maximum can reach up to 25.3%). Furthermore, the as-prepared N-CDs are applied as fluorescence probes to detect acetone and H2O2 in water. This method has exhibited a low detection limit of acetone (less than 0.1%) and a quick and linear response to the H2O2 with the concentration from 0 to 120 μmol/L. This work broadens the knowledge of applying CDs as probes in the bio and chemical sensing fields.
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