Metal-organic gel as a fluorescence sensing platform to trace copper(II).

Metal-organic gel (MOG), as a novel type of metallic organic hybrid material, exhibits diverse properties. However, its application in fluorescence detection for specific metal ions has rarely been exploited. In this work, we have designed and synthesized a MOG based on Al-carboxylate coordination assemblies (denoted as MOG-Al). The resultant MOG-Al shows good specific fluorescence signal response to trace Cu2+. Under optimal conditions, the fluorescence quenching degrees (F0 - F) of the MOG-Al have a linear correlation with Cu2+ concentration ranging from 0.05 to 100 µM, and the limit of detection (LOD) is 45.00 nM. The proposed sensing platform was also applied for the detection of Cu2+ in real samples. Satisfactory recoveries (92-116%) for Cu2+ in rice, soybean milk powder and pork liver were obtained. These results indicate that MOG-Al is a promising material for the specific and sensitive sensing of Cu2+.

Strong Visible Light Absorption and Abundant Hotspots in Au-Decorated WO3 Nanobricks for Efficient SERS and Photocatalysis.

Metal/semiconductor hybrids show potential application in fields of surface-enhanced Raman spectroscopy (SERS) and photocatalysis due to their excellent light absorption, electric field, and charge-transfer properties. Herein, a WO3-Au metal/semiconductor hybrid, which was a WO3 nanobrick decorated with Au nanoparticles, was prepared via a facile hydrothermal method. The WO3-Au hybrids show excellent visible light absorption, strong plasmon coupling, high-performance SERS, and good photocatalytic activity. In particular, on sensing rhodamine B (RhB) under 532 nm excitation, bare WO3 nanobricks have a Raman enhancement factor of 2.0 × 106 and a limit of detection of 10-8 M due to the charger-transfer property and abundant oxygen vacancies. WO3-Au metal/semiconductor hybrids display a largely improved Raman enhancement factor compared to pure Au and WO3 components owing to the synergistic effect of electromagnetic enhancement and charge transfer. The Raman enhancement factor and limit of detection are further improved, reaching 5.3 × 108 and 10-12 M, respectively, on increasing the content of Au to 2.1 wt %, owing to the strong plasmon coupling between the Au nanoparticles. Additionally, the WO3-Au hybrids also exhibit excellent photocatalytic activity toward degradation of RhB under visible light irradiation. WO3-Au (2.1 wt %) possesses the fastest photocatalytic rate, which is 6.1 and 2.0 times that of pure WO3 nanobricks and commercial P25, respectively. The enhanced photocatalytic activity is attributed to the strong plasmon coupling and the efficient charge transfer between Au and WO3 nanobricks. The as-prepared materials show great potential in detecting and degrading pollutants in environmental treatment.

[Remediation performance and mechanism of aquatic plants for iron polluted water]. / 水生植物修复铁污染水体的效果及作用机制.

To solve the yellow colorization in water caused by iron ion, we evaluated the remediation performances of six aquatic plant species (Hygroryza aristata, Myriophyllum verticillatum, Hydrocotyle verticillata, Jussiaea stipulacea, Pistia stratiotes and Rotala rotundifolia) using hydroponic experiment. Effects of iron concentration, pH, plant biomass on iron removal were investigated, and the intensification of removing iron incurred by aeration was also discussed. Results showed that all the examined plant species could improve both divalent iron and total iron removal, but with significant difference in their performance. Divalent iron concentrations were decreased by H. aristata and H. verticillata from 5.0 mg·L-1 to 0.23 and 0.26 mg·L-1 within 24 h, respectively, meeting the standard of supplementary items for the drinking water and surface water sources (divalent iron concentration ≤0.3 mg·L-1), while total iron concentrations declined to 0.84 and 1.21 mg·L-1 with removal efficiency of 83.2% and 75.8%, respectively. Concentrations of divalent iron and total iron of plant treatment plots at pH 5, 6, 7, 8 were not significantly different, with removal efficiency of divalent iron and total iron being among 95.4%-98.4% and 92.2%-94.6%, separately. When initial divalent iron concentration was less than 5.0 mg·L-1, removal efficiency of divalent iron and total iron increased with the increases of divalent iron concentration. The growth of H. aristata was inhibited at divalent iron concentration of 10.0 mg·L-1. Total iron removal was not stable during the trial. Removal efficiency of plant treatment rose only by 7.0% compared with the control, which was much lower than other concentration treatments. The divalent iron concentration was decreased to ＜ 0.3 mg·L-1 in 24 h at plant biomass :300 g, with no difference of removal efficiency among biomass treatments. Both intermittent and continuous aeration enhanced iron removal by H. aristata, but continuous aeration was more favorable for the removal of total iron due to stabilization.

Surface chemistry modified upconversion nanoparticles as fluorescent sensor array for discrimination of foodborne pathogenic bacteria.

BACKGROUND: The identification of foodborne pathogenic bacteria types plays a crucial role in food safety and public health. In consideration of long culturing times, tedious operations and the desired specific recognition elements in conventional methods, the alternative fluorescent sensor arrays can offer a high-effective approach in bacterial identification by using multiple cross-reactive receptors. Herein, we achieve this goal by constructing an upconversion fluorescent sensor array based on anti-stokes luminogens featuring a series of functional lanthanide-doped upconversion nanoparticles (UCNPs) with phenylboronic acid, phosphate groups, or imidazole ionic liquid. The prevalent spotlight effect of microorganism and the electrostatic interaction between UCNPs and bacteria endow such sensor array an excellent discrimination property. RESULTS: Seven common foodborne pathogenic bacteria including two Gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes) and five Gram-negative bacteria (Escherichia coli, Salmonella, Cronobacter sakazakii, Shigella flexneri and Vibrio parahaemolyticus) are precisely identified with 100% accuracy via linear discriminant analysis (LDA). Furthermore, blends of bacteria have been identified accurately. Bacteria in real samples (tap water, milk and beef) have been effectively discriminated with 92.1% accuracy. CONCLUSIONS: Current fluorescence sensor array is a powerful tool for high-throughput bacteria identification, which overcomes the time-consuming bacteria culture and heavy dependence of specific recognition elements. The high efficiency of whole bacterial cell detection and the discrimination capability of life and death bacteria can brighten the application of fluorescence sensor array.