Colorimetric detection for uranyl ions in water using vinylphosphonic acid functionalized gold nanoparticles based on smartphone.

A simple and portable colorimetric sensor for colorimetric detection of UO22+ in aqueous solution based on vinylphosphonic acid functionalized gold nanoparticles (VPA-AuNPs) has been developed. The VPA-AuNPs solution was prepared by sodium borohydride reduction in the presence of vinylphosphonic acid. The addition of UO22+ would induce aggregation of VPA-AuNPs, resulting in the color change from wine-red to blue, and red-shift of the ultraviolet-visible (UV-vis) spectra. The UO22+ assay based on VPA-AuNPs showed good selectivity and sensitivity, with a limit of detection to be approximately 2.0 µM by naked eyes and 1.07 µM by UV-vis (S/N = 3) respectively. Additionally, a smartphone with a free application named "PhotoMetrix" was employed to estimate the color intensities (red, green, blue value) of VPA-AuNPs in the presence of UO22+ with different concentrations, and the concentration of UO22+ samples could be conveniently exported by the calculated univariate calibration curves. This method shows good feasibility for on-site UO22+ detection in an aqueous solution.

Pd-Ru nanocatalysts derived from a Pd-induced aerogel for dramatic boosting of hydrogen release.

Alloyed bimetallic Pd-Ru nanocatalysts prepared by in situ reduction of a mixture of a Ru(iii) source and a Pd(ii)@alkyne-PVA aerogel and characterized by TEM and XPS exhibit very highly catalytic activity towards hydrogen release from ammonia borane hydrolysis with a TOF value of 578.2 molH2 molcat-1 min-1.

Nanoscale zero-valent iron intercalated 2D titanium carbides for removal of Cr(VI) in aqueous solution and the mechanistic aspect.

MXenes, as new members of the 2D materials group, are regarded as good candidates for heavy metal removal particularly for radioactive metal element because of their high irradiation stability. However, the small interlayer distance and lack of active sites on the surface limit their further application. In this report, nanoscale zero-valent iron has been introduced into the inter-layer structure of alkaline intercalated Ti3C2 (Alk-Ti3C2) and investigated to Cr(VI) removal. The XPS spectra, SEM images, TEM images, and N2 adsorption-desorption isotherms characterizations revealed that the OH groups on the Alk-Ti3C2 surface assisted the introducing of nZVI into the inter-layer of Alk-Ti3C2 and subsequently stabilized the nZVI. The increased active sites of nZVI and extended interlayer space of Alk-Ti3C2 could improve the uptake capacity of Cr(VI) (194.87 mg/g at pH = 2). The highly efficient removal of Cr(VI) was maintained even in the presence of coexisting cations, which showed great potential for real environment remediation. Mechanistic study indicated that the synergistic effects of nZVI and Alk-Ti3C2 nanosheet in nZVI-Alk-Ti3C2 composites are keys for Cr(VI) removal.

MicroRNA-429 inhibits cancer cell proliferation and migration by targeting the AKT1 in melanoma.

MicroRNAs (miRNAs; miR) have been proven to act as both oncogenes and tumor suppressors. However, the mechanism of action of miR429 in melanoma cells remains to be elusive. The present study aims to explain the functional role and mechanism of miR429 in the pathogenesis of melanoma. In our study, we have demonstrated that has-miRNA429 (miR429) is a tumor suppressor in melanoma cells. Luciferase reporter assays demonstrated that the overexpression of miR429 reduced the transcriptional activity of AKT serine/threonine kinase 1 (AKT1). Furthermore, the results showed that the mRNA and protein expression levels of AKT1 were downregulated in the melanoma cell lines when miR429 was overexpressed according to qRT-PCR and western bolt, indicating MicroRNA-429 may directly target AKT1 in melanoma. In vivo, overexpression miR-429 could obviously enhance the inhibition effect of tumor size and weight in the nude mice. Taken together, our findings suggest that novel miR429-regulated pathway may serve as new insights into melanoma oncogenesis and metastasis.

Development of a novel tridentate ligand for colorimetric detection of Mn2+ based on AgNPs.

A novel tridentate ligand nitrilotris(methylene)tris(1,2,3-triazole)triacetate (NTTTA) has been synthesized by click reaction and followed with ester hydrolysis reaction. The silver nanoparticles (AgNPs) were then modified and stabilized by this ligand, and subsequently been employed for the highly selective and sensitive colorimetric detection of Mn2+ in aqueous solution. The presence of Mn2+ can cause the aggregation of AgNPs, which leads to the color change of the dispersion from yellow to brown, as well as the decrease and red-shift of the surface plasmon resonance absorption. The detection limit of Mn2+ was as approximately 0.5 µM by the naked eyes. UV-vis spectroscopy analysis showed a good linear relationship between the logarithm of the ratios (A550/A395) and the concentration of Mn2+over the range of 0.05 µM-10 µM, and the LOD was calculated to be 12.6 nM (S/N = 3). The present assay showed good simplicity without the need of adjusting the pH value. The feasibility of this technique was evaluated for successful detection of Mn2+ in tap water and lake water samples, with good recoveries.

Synergistic effect of additives on cyclopropanation of olefins.

An efficient cyclopropanation of olefins with Zn(CH2I)2, a catalytic amount of CCl3CO2H, and 1,2-dimethoxyethane at room temperature is described. A wide variety of olefins, including acid-sensitive substrates, can be cyclopropanated in 71-99% yield.

Enantioselective bromoaminocyclization of allyl N-tosylcarbamates catalyzed by a chiral phosphine-Sc(OTf)3 complex.

An effective enantioselective bromoaminocyclization of allyl N-tosylcarbamates catalyzed by a chiral phosphine-Sc(OTf)3 complex is described. A wide variety of optically active oxazolidinone derivatives containing various functional groups can be obtained with high enantioselectivities.

Enantioselective bromocyclization of olefins catalyzed by chiral phosphoric acid.

A chiral phosphoric acid catalyzed enantioselective bromocyclization of olefins is described. Various cis-, trans-, or trisubstituted γ-hydroxy-alkenes and γ-amino-alkenes can cyclize under the reaction conditions to give optically active 2-substituted tetrahydrofurans and tetrahydropyrroles in up to 91% ee.

FeCl3/NaI-catalyzed allylic C-H oxidation of arylalkenes with a catalytic amount of disulfide under air.

This paper describes a FeCl(3)/NaI-catalyzed formal allylic C-H oxidation of arylalkenes using a catalytic amount of disulfide with BnOH and 4-nitroaniline as nucleophiles and air as oxidant to form the corresponding allyl ethers and amines. A possible reaction mechanism has been proposed.

Acid-catalyzed regioselective sulfetherification of alkenols and stereoselective rearrangement of tetrahydrofuran to tetrahydropyran.

An efficient acid-catalyzed sulfetherification of various unsaturated alcohols with sulfenamides to form tetrahydrofurans and tetrahydropyrans regioselectively is described. Mechanistic studies have shown that the tetrahydrofurans can stereoselectively rearrange to the corresponding tetrahydropyrans.

An acid-catalyzed formal allylic C-H oxidation of aryl cycloalkenes with N-propylthiosuccinimide.

A mild acid-catalyzed formal allylic C-H oxidation of aryl cycloalkenes with N-propylthiosuccinimide in the presence of various nucleophiles to generate allylic ethers, esters, and sulfonamides is described. A possible reaction mechanism has been proposed.