Precious-metal free photocatalytic production of an NADH analogue using cobalt diimine-dioxime catalysts under both aqueous and organic conditions.

The photocatalytic generation of an NADH synthetic analogue, i.e. 1-benzyl-1,4-dihydronicotinamide (1,4-BNAH), has been studied using the cobalt diimino-dioxime complexes and the BF2-bridged derivative as catalysts. 1,4-BNAH was produced in both aqueous and organic media at unprecedented turnover numbers with metal and organic photosensitizers, respectively.

The Important Role of Coordination Geometry on Photophysical Properties of Blue-Green Emitting Ruthenium(II) Diisocyano Complexes Bearing 2-Benzoxazol-2-ylphenolate.

A series of blue-green emitting RuII diisocyano complexes containing 2-benzoxazol-2-ylphenolate (PBO) have been prepared. The complexes were isolated under varied reaction conditions in two isomeric forms, i.e., trans,trans,trans- (1) and cis,trans,cis- (2), with varied ligand coordination geometry above the RuII center. The photoluminescence of the isomeric complexes has been compared and tuned by the systematic variation of the electronic properties of the isocyanides. The cis,trans,cis- isomers exhibit structureless emission in the blue-green region (471-517 nm) upon excitation at λex > 400 nm in dichloromethane solution at room temperature. Both isomeric forms show similarly structured greenish emission at 499-523 nm on excitation at λex > 355 nm in a methanol/ethanol (4:1) glassy medium at 77 K. On careful comparison with the corresponding absorption and electrochemical data, it is suggested that the solution emission of the cis,trans,cis- isomers (2) at room temperature is originated from the metal-to-ligand charge transfer (MLCT), while a ligand-centered (LC) parentage is assigned for the emission in a glassy state for both isomeric forms. In line with the above experimental results, DFT calculation demonstrates the change in the nature and relative energy of the HOMOs and LUMOs with respect to the varied ligand coordination geometry and π-accepting ability of the isocyanides.

Catalyst displacement assay: a supramolecular approach for the design of smart latent catalysts for pollutant monitoring and removal.

Latent catalysts can be tuned to function smartly by assigning a sensing threshold using the displacement approach for targeted analytes. Three cyano-bridged bimetallic complexes were synthesized as "smart" latent catalysts through the supramolecular assembly of different metallic donors [FeII(CN)6]4-, [FeII(tBubpy)(CN)4]2-, and FeII(tBubpy)2(CN)2 with a metallic acceptor [CuII(dien)]2+. The investigation of both their thermodynamic and kinetic properties on binding with toxic pollutants provided insight into their smart off-on catalytic capabilities, enabling us to establish a threshold-controlled catalytic system for the degradation of pollutants such as cyanide and oxalate. With these smart latent catalysts, a new catalyst displacement assay (CDA) was demonstrated and applied in a real wastewater treatment process to degrade cyanide pollutants in both domestic (level I, untreated) and industrial wastewater samples collected in Hong Kong, China. The smart system was adjusted to be able to initiate the catalytic oxidation of cyanide at a threshold concentration of 20 µM (the World Health Organization's suggested maximum allowable level for cyanide in wastewater) to the less harmful cyanate under ambient conditions.

Development of sensitive and selective food sensors using new Re(I)-Pt(II) bimetallic complexes to detect volatile biogenic sulfides formed by meat spoilage.

Detection of volatile biogenic sulfides (VBS) plays a crucial role in food safety because the amounts of these compounds can reflect the freshness of meat. A new indicator-displacement assay with Re(I)-Pt(II) complexes, [Re(Lig)(CO)3(bridge)]-[Pt(DMSO)(Cl)2] (1: Lig=5-phenyl-1,10-phenanthroline and bridge=NCS(-); 2: Lig=5-phenyl-1,10-phenanthroline and bridge=CN(-); 3: Lig=2,2'-biquinoline and bridge=NCS(-)), was demonstrated to be a very effective sensing method to VBS. The results indicated that the control of Re(I)-bridge-Pt(II) and Re(I)-ligand combination are able to regulate their sensing selectivity and sensitivity. This system was successfully applied to detect CH3SCH3 in real rotten pork with a linear luminometric response up to 20.0mgkg(-1) (R=0.997) with the detection limit as 0.05 mgkg(-1). Complex 1 also gave comparable results on the detection of VBS with respect to those determined by GCMS with recovery range from 76% to 102% (RSD%=13.8).

Doxorubicin-loaded biodegradable self-assembly zein nanoparticle and its anti-cancer effect: Preparation, in vitro evaluation, and cellular uptake.

Cancer is one top leading cause of the deaths worldwide. Various anticancer drugs, which can effectively kill cancer cells, have been developed in the last decade. However, the problem is still about the low therapeutic index of the drugs, which means that the effective dose of drugs will cause cytotoxicity to normal cells. A strategy based on drug nano-encapsulation is applied to achieve an effective anti-cancer therapy. In this study, we use zein, which is an amphiphilic protein, to make the anti-cancer drug nano-encapsulation. Doxorubicin (DOX), a popular anti-cancer drug, is selected as the core drug. The results show that DOX could be successfully encapsulated into zein to form spherical nanoparticles. The encapsulation efficiency and loading efficiency could reach as high as 90.06% and 15.01 mg/g, respectively. The cumulative release result showed a desired pH-responsible release behavior: DOX could be released faster in acidic buffer solutions (pH 5.0 and 6.5) than neutral one (pH 7.4). The effects of the nano-encapsulation on the anti-proliferation of HeLa cells were also examined. It indicated that, compared with free DOX, the DOX-loaded zein nanoparticles (DOX-zein-NPs) had a better effect on cancer cell killing at low DOX concentrations. We also investigated the cellular uptake of DOX-zein-NPs using confocal laser scanning microscopy (CLSM), flow cytometry, and transmission electron microscopy (TEM). And the endocytosis mechanism of DOX-zein-NPs entering into HeLa cells was studied using various endocytosis pathway inhibitors.

A Multifunctional Bimetallic Molecular Device for Ultrasensitive Detection, Naked-Eye Recognition, and Elimination of Cyanide Ions.

A new bimetallic Fe(II) -Cu(II) complex was synthesized, characterized, and applied as a selective and sensitive sensor for cyanide detection in water. This complex is the first multifunctional device that can simultaneously detect cyanide ions in real water samples, amplify the colorimetric signal upon detection for naked-eye recognition at the parts-per-million (ppb) level, and convert the toxic cyanide ion into the much safer cyanate ion in situ. The mechanism of the bimetallic complex for high-selectivity recognition and signaling toward cyanide ions was investigated through a series of binding kinetics of the complex with different analytes, including CN(-) , SO4 (2-) , HCO3 (-) , HPO4 (2-) , N3 (-) , CH3 COO(-) , NCS(-) , NO3 (-) , and Cl(-) ions. In addition, the use of the indicator/catalyst displacement assay (ICDA) is demonstrated in the present system in which one metal center acts as a receptor and inhibitor and is bridged to another metal center that is responsible for signal transduction and catalysis, thus showing a versatile approach to the design of new multifunctional devices.

An Ru(II)-Fe(III) bimetallic complex as a multifunctional device for detecting, signal amplifying, and degrading oxalate.

A tetranuclear bimetallic complex, [Ru(II)((t)Bubpy)(CN)4]2-[Fe(III)(H2O)3Cl]2·8H2O (1) has been synthesized and characterized. It was found to be a multifunctional device that can detect, signal amplify, and degrade an organic pollutant, oxalate. Results of the chemosensing studies of 1 toward common anions show that only oxalate selectively induces naked-eye colorimetric and luminometric responses with method detection limits down to 78.7 and 5.5 ppm, respectively from 1. Meanwhile, results of the photo-degradation studies of 1 toward oxalate show that the dissolved organic carbon content of oxalate decreased and reached complete mineralization into CO2 within 6 hours. Complex 1 was also found as the catalyst that amplified the detection signal toward oxalate. Through the photoassisted Fenton reaction by 1, methyl orange, an additional coloring agent, could be degraded so that the visual detection limit of 1 toward oxalate was magnified 50 times from 100 to 2 ppm. The detection, degradation, mineralization and signal amplification were found applicable in real water bodies such as river, pond and underground water with excellent recoveries and relative standard deviation.