Latest ArticlesIn this paper, norbornene imidazolium hexafluorophosphate (NM-MIm-PF6) was modified on the surface of aminopropyl silica by ring-opening metathesis polymerization (ROMP), and then oligo(ethylene glycol) methacrylate (OEGMA) were grafted on the surface by atom transfer radical polymerization (ATRP). Some characterizations in this article confirmed that the synthesis of P(NM-MIm-PF6)-SiPOEGMA (P1-Si-P2) is successful. The P1-Si-P2 can separate sugars, amino acids, sulfonamides in a hydrophilic interaction mode and alkyl benzene, polycyclic aromatic hydrocarbon in a reverse phase mode. The experiment also found that the column has typical characteristics of hydrophobic/hydrophilic separation mechanism. Compared to single hydrophobic C18 column and single hydrophilic Si-NH2 column, this P1-Si-P2 shows certain advantages.
Nitrogen photofixation using g-C3N4-based photocatalysts have attracted abundant of attentions recently. Herein, in this study, holey g-C3N4 (HGCN) nanosheets possess a good deal of carbon vacancies were prepared by means of thermally treating bulk g-C3N4 (BGCN) under an NH3 atmosphere. Characterization analysis revealed that the as-synthesized sample have identical crystal structure, larger BET specific surface area, stronger reduction capability, and higher photogenerated charge carrier separation rate than that of BGCN. These properties may contribute to enhance the nitrogen photofixation activity. It was also found that the rate of NH4+ production for N2 photofixation of HGCN sample reached~25.54 mg L-1 h-1 gcat-1, which is approximately~5.87 times higher than that of BGCN sample under optimal reactive conditions. Moreover, a plausible mechanism of HGCN for nitrogen photofixation process was illuminated in detail.
β-Elemene is a volatile oil used for the treatment of cancer, but poor solubility, low bioavailability, and various adverse reactions limit its application. For ameliorating risks of the venous toxicity of β-elemene, intravenously injectable micelle of β-elemene was prepared using the thin-film hydration method. The results pointed out the micelles were uniformly spherical with about 20.96 ± 0.1966 nm in average diameter and exhibited high entrapment efficiency (99.02% ± 0.88%). As revealed by drug release studies in vitro, β-elemene micelles had sustained drug release. Compared with free β-elemene, the micelles increased the drug cellular uptake and enhanced the anti-tumor effect in vitro through retarding cell cycle and inducing apoptosis. Meanwhile, the elevated serum stability of β-elemene micelles implied less drug leakage and reduced toxicity. The wound healing and tube formation assay in vitro demonstrated the anti-metastasis and anti-angiogenesis effects of β-elemene micelles. Moreover, the pharmacokinetics study showed the AUC and T1/2 of β-elemene in micelle group were 1.79 and 1.62 times of that in free β-elemene group, suggesting the circulation time of β-elemene in the blood had been prolonged. In addition, β-elemene micelles showed a favorable antitumor response compared with the β-elemene solution on C26 colon cancer-bearing mice model. Local irritation study investigated in rabbits indicated that the β-elemene micelles strikingly mitigated the irritation to the injection sites compared with free β-elemene. These results proved that the micelle could be a good candidate as an auspicious drug delivery system of β-elemene for the prospective clinical treatment of carcinoma.
Spirooxindoles play an important role in drug discovery and development. The development of efficient methods for the synthesis of spirooxindoles from easily available starting materials is of current interest. Herein, we report in detail the In(OTf)3-catalyzed [3 + 3] annulation of spirocyclopropyl oxindoles and 1, 4-di-thiane-2, 5-diol, which allows the facile preparation of spiro[indoline-3, 4'-thiopyran]-2-ones bearing (tetrahydro)thiopyran skeleton.
Silicon (Si) materials as anode materials for applications in lithium-ion batteries (LIBs) have received increasing attention. Among the Si materials, the electrochemical properties of SiOx-based (0 < x ≤ 2) composites are the most prominent. However, due to the cycling stability of SiOx being far from practical, there are some problems, such as low initial coulombic efficiency (ICE), obvious volume expansion and poor conductivity. Researchers in various countries have optimized the electrochemical properties of SiOx-based composites by means of pore formation, surface modification, and the choice of constituents. In this review, SiOx-based composites are classified into three categories based on the valency of Si (SiO2 composites, SiO composites and SiOx (0 < x < 2) composites). The synthesis, morphologies and electrochemical properties of the SiOx-based composites that are applied in LIB are discussed. Finally, the properties of several common SiOx-based composites are briefly compared and the challenges faced by SiOx-based composites are highlight.
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.
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.
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.
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.
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