Sources and spatial variations of heavy metals in offshore sediments of the western Pearl River Estuary.

The concentrations of six heavy metals (Cd, Cr, Cu, Pb, Zn, and As) in offshore surface sediments of western Pearl River Estuary were analyzed to investigate their sources and spatial variations using factorial kriging analysis. Three-scale spatial variations in heavy metal concentrations were identified and separated: nugget, local, and regional scale, which indicated sample errors, anthropogenic pollution and natural variation, respectively. Anthropogenic heavy metals varied sharply and heterogeneous at range of 60 km. Maoming Port, Hailing Bay and coastal area northeastern Hainan Island were potential polluted areas of Cd, Cr, Cu, Pb, Zn and As, also the Nandu River, Baoling River and Wanquan River estuaries were potential polluted areas of As. These polluted areas ranged up to 60 km in size and tended to extend with currents. The natural heavy metals varied continuously and relatively homogeneous at range of 180 km, which was dominated by riverine input and paleo-sea-level changes.

A carbon dots/rutin system for colorimetric and fluorimetric dual mode detection of Al3+ in aqueous solution.

In this work, colorimetric and fluorimetric dual mode detection of Al3+ in aqueous solution was achieved using a carbon dots/rutin (CDs/rutin) coexisting system. Upon addition of Al3+, a yellow Al(iii)-rutin complex was formed without any interaction between Al3+ and the carbon dots (CDs). As a result, a new absorption peak of the complex at 430 nm increased while the peak of rutin at 360 nm decreased. Therefore, a ratiometric colorimetric method for the detection of Al3+ was built on a good linear relationship between the absorbance ratio (A430 nm/A360 nm) and the concentration of Al3+ in a wide linear range from 2.0 to 40.0 µM, with a limit of detection (LOD) as low as 0.38 µM. More interestingly, the excitation spectrum of the CDs overlapped with the absorption band of the Al(iii)-rutin complex, resulting in an inner filter effect on the fluorescence of the CDs. Accordingly, a fluorimetric approach was developed on an excellent linear relationship between (F0 - F)/F0 and the concentration of Al3+ in the range from 0.8 to 20.0 µM, with an LOD of 0.32 µM. Finally, the spiked Al3+ in real samples (tap water and lake water) was recovered by the as-proposed dual mode detection with high accuracy.

Detection of metronidazole in honey and metronidazole tablets using carbon dots-based sensor via the inner filter effect.

In this work, carbon dots (CDs) with a high quantum yield (22.3%) were easily prepared by hydrothermal pyrolysis of acid fuchsin 6B and hydrogen peroxide at 180°C for 10 h. The resultant CDs possess a narrow size distribution in the range of 2.6 to 3.2 nm and emit blue fluorescence. Interestingly, the absorption band of metronidazole (MTZ) centered at 318 nm can complementary overlap with the excitation band of the as-prepared CDs centered at 320 nm, resulting in an inner filter effect (IFE) in high efficiency. In fact, the fluorescence quenching of the CDs depends on the concentration of MTZ. Therefore, a simple method for the detection of MTZ can be established using the CDs-based sensor via the IFE. The linear range of the proposed method was 0-10 µg mL-1 with the limit of detection as low as 0.257 µg mL-1 . This CDs-based sensor had been applied for the detection of MTZ in honey and MTZ tablets with the recoveries in the range of 98.0% to 105.1% and 95.7% to 106.5%, respectively. Therefore, the as-prepared CDs have a potential to be developed as a MTZ sensor with high selectivity, sensitivity and accuracy.

Novel 19 F-MRS ß-galactosidase reporter molecules incorporated nitrogen mustard analogues.

In this study, we propose a novel molecular platform-integrated fluorinated antitumor nitrogen mustards for 19 F-MRS assay of ß-galactosidase (ß-gal) activity. Following this idea, we have designed, synthesized, and characterized 2-fluoro-4-[bis(2'-chloroethyl)amino]phenyl ß-D-galactopyranoside 5, 2-fluoro-4-{bis[2'-O-(ß-D-galactopyranosyl)ethyl]amino}phenyl ß-D-galactopyranoside 8, 2-fluoro-4-{bis[[1″-(ß-D-galactopyranosyl)-1″, 2″, 3″-triazol-4″-yl]methyl] amino}phenyl ß-D-galactopyranoside 14 and 2-fluoro-4-{bis[[1″-(ß-D-glucopyranosyl)-1″, 2″, 3″-triazol-4″-yl]methyl]amino}phenyl ß-D-galactopyranoside 15 through glycosylation and click reaction strategies, and their structures were confirmed by NMR and HRMS or elemental analysis data. Among them, 2-fluoro-4-[bis(2'-chloroethyl)amino]phenyl ß-D-galacto-pyranoside 5 was found very sensitive to ß-gal (E801A) in PBS at 37°C with big ΔδF response. Here, we demonstrated the feasibility of this platform for assessing ß-gal activity in solution, and in vitro with lacZ-transfected human MCF7 breast and PC3 prostate tumor cells, by the characterization of ß-gal-responsive 19 F-chemical shift changes ΔδF and hydrolytic kinetics.