A MELET- and IFE-based UV-visible luminescent ratiometric probe for quantization of mercury(II) and nitrofurantoin in environmental sewage.

A novel fluorimetric ratiometric probe of green and eco-friendily nitrogen-enriched, oxygen-doped carbon nanodots (Cnanodots) was prepared for the quantitative analysis of mercury(II) (HgII) and nitrofurantoin (Nit) in the environmental sewage. The Cnanodots exhibits dual-emission peaks respectively at 345 and 445 nm under 285 nm excitation, with excitation-independent properties. Unexpectedly, this Cnanodots displays two obvious ratiometric responses to HgII and Nit through decreasing the signal at 345 nm and remaining invariable at 445 nm. Experimental results confirm that the highly sensitive analysis of HgII and Nit are achieved respectively based on matching energy-level electron transfer and inner filter effect mechanisms. The fluorescence (FL) ratiometric intensity of [FL345nm/FL445nm] expresses a good linear relationship with the concentration of HgII in the scope of 0.01-20 µM, while the logarithm of [Log(FL0345nm-FL345nm)] on the quenching degree of the probe by Nit also shows a good linear correlation within the range of 0.01-100 µM. The detection limits were calculated to be 4.14 nM for HgII, and 7.84 nM for Nit. Moreover, recovery experiments of Cnanodots for HgII and Nit sensing in real sewage samples obtained satisfactory results, comfirming the feasibility of practical application.

Upon DFT-D3 dispersion correction and ECD spectral confirmation, only several conformers can stably coexist for three fungal cycloaspeptides (A, D, G).

Dispersion correction in theoretical determination of cyclopeptide conformations is emphasized. Whether in gas approximation or in solvation simulation, the density functional theory with London dispersion correction (DFT-D3) demonstrates that only 2-3 conformers can stably coexist for cycloaspeptides (A, D, G) at B3LYP-D3 and CAM-B3LYP-D3. Conformational rationality is confirmed by electronic circular dichroism (ECD). Whether for Cotton effect or for excitation energy, TD-B3LYP-D3 has better performances than TD-CAM-B3LYP-D3 because the former can better reproduce the experiment. A molecular orbital analysis is used to interpret ECD, where two energy bands observed in experiment originates from the ππ* transitions other than the σπ* transitions. Long-range correction and solvent effect make H-bonds shorten, and dispersion correction makes them further shorten.

A highly hydrolytically stable lanthanide organic framework as a sensitive luminescent probe for DBP and chlorpyrifos detection.

Organic pollutants have attracted increasing attention due to their strong persistence and extensive diffusivity. Plasticizers (PAEs) and organophosphorus pesticides (OPs), as the vital part of organic pollutants, have made extensive damage to the environment with the rapid development of modern agriculture and industry. Therefore, we have, for the first time, carried out a quantitative analysis of the PAEs and OPs by fluorescence recognition. A series of isostructural lanthanide organic frameworks, [Ln(tftpa)1.5(2,2'-bpy)(H2O)] (Ln = Gd 1, Eu 2 and Tb 3, H2tftpa = tetrafluoroterephthalic acid), were hydrothermally synthesized, of which 3 exhibited excellent hydrolytic resistance to both boiling acidic and basic aqueous solutions. Moreover, luminescence investigations show that 3 can be used as a highly sensitive and recyclable luminescence sensor for the detection of DBP (di-n-butyl phthalate) in simulated seawater and chlorpyrifos in ethanol with the detection limits of 2.07 and 0.14 ppb, respectively.

Theoretical searches and spectral computations of preferred conformations of various absolute configurations for a cyclodipeptide, cordycedipeptide A from the culture liquid of Cordyceps sinensis.

A cyclic dipeptide often has the multiple configurations and the abundant conformations. The density functional theory (DFT) method is used to search the preferred conformation of the most probable configuration for cordycedipeptide A isolated from the culture liquid of Cordyceps sinensis. The time-dependent DFT approach is exploited to describe the profile of electronic circular dichroism (CD). The calculated results show that the most probable configuration is 3S6R7S, whose preferred conformation has a negative optical rotation and a positive lowest energy electronic CD band.

Minimum polarizability principle applied to lowest energy isomers of some gaseous all-metal clusters.

In comparison with the minimum energy criterion as an indicator of the most stable state, the minimum polarizability and maximum hardness principles have been examined to describe the relative stability of various isomers of nine gaseous all-metal clusters M4X- (Cu4Na-, Cu4Li-, Al4Cu-, Ag4Li-, Au4Li-, Ag4Na-, Au4Na-, Al4Ag-, Al4Au-) on the basis of MP2 calculations. In these species, there are two lowest energy isomers with near isoenergy that sometimes make it very difficult to determine which of them is more stable when we depend only on the minimum energy criterion. According to the minimum polarizability principle, however, the square-pyramidal structure is always more stable than the planar isomer at various computational levels, which was also confirmed by the results from the minimum energy principle that sometimes requires higher computational precision. Thus, there is an indication that, at least for our present cluster system, the minimum polarizability principle is less dependent on the computational levels compared to the minimum energy principle.

Geldanamycin inhibits proliferation and motility of human HER2/neu-overexpressing breast cancer cell line SKBr3 / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the antitumor effect of a benzoquinone ansamycin antibiotic, geldanamycin (GA), against HER2 /neu tyrosine kinase-overexpressing human breast cancer cell line SKBr3.</p><p><b>METHODS</b>To evaluate the antitumor activity of GA, the degradation of HER2 /neu tyrosine kinase in GA-treated SKBr3 cells was analyzed by Western blotting, their proliferation assessed using MTT assay, and the cell cycle distribution identified by flow cytometry. RT-PCR and Real-time PCR were employed to detect cyclin D1 mRNA expression and cell culture inserts model was used to evaluate the motility of the cells.</p><p><b>RESULTS</b>GA induced a dose- and time-dependent degradation of HER2 /neu tyrosine kinase and cell proliferation inhibition. GA treatment obviously decreased the survival rates of the cancer cells, leading also to a dose-dependent G(1) arrest. The antitumor effects of GA proved to be relevant with declined transcription of cyclin D1. The GA-treated cells also exhibited reduced motility.</p><p><b>CONCLUSION</b>GA can efficiently destabilize HER2 /neu tyrosine kinase and inhibit the proliferation and motility of human breast cancer cell line SKBr3 overexpressing HER2 /neu tyrosine kinase.</p>