Ruizhuo Ouyang

Electrocatalysis and electroanalysis of nickel, its oxides, hydroxides and oxyhydroxides toward small molecules

The electrocatalysis toward small molecules, especially small organic compounds, is of importance in a variety of areas. Nickel based materials such as nickel, its oxides, hydroxides as well as oxyhydroxides exhibit excellent electrocatalysis performances toward many small molecules, which are widely used for fuel cells, energy storage, organic synthesis, wastewater treatment, and electrochemical sensors for pharmaceutical, medical, food or environmental analysis. Their electrocatalytic mechanisms are proposed from three aspects such as Ni(OH)2/NiOOH mediated electrolysis, direct electrocatalysis of Ni(OH)2 or NiOOH. Under exposure to air or aqueous solution, two distinct layers form on the Ni surface with a Ni hydroxide layer at the air-oxide interface and an oxide layer between the metal substrate and the outer hydroxide layer. The transformation from nickel or its oxides to hydroxides or oxyhydroxides could be further speeded up in the strong alkaline solution under the cyclic scanning at relatively high positive potential. The redox transition between Ni(OH)2 and NiOOH is also contributed to the electrocatalytic oxidation of Ni and its oxides toward small molecules in alkaline media. In addition, nickel based materials or nanomaterials, their preparations and applications are also overviewed here.

Artificial receptor-functionalized nanoshell: facile preparation, fast separation and specific protein recognition

This work combined molecular imprinting technology with superparamagnetic nanospheres as the core to prepare artificial receptor-functionalized magnetic nanoparticles for separation of homologous proteins. Using dopamine as a functional monomer, novel surface protein-imprinted superparamagnetic polydopamine (PDA) core-shell nanoparticles were successfully prepared in physiological conditions, which could maintain the natural structure of a protein template and achieved the development of molecularly imprinted polymers (MIPs) from one dimension to zero dimension for efficient recognition towards large biomolecules. The resultant nanoparticles could be used for convenient magnetic separation of homologous proteins with high specificity. The nanoparticles possessed good monodispersibility, uniform surface morphology and high saturation magnetization value. The bound amounts of template proteins measured by both indirect and direct methods were in good agreement. The maximum number of imprinted cavities on the surface of the bovine hemoglobin (Hb)-imprinted nanoshell was 2.21 x 10(18) g( - 1), which well matched their maximum binding capacity toward bovine Hb. Both the simple method for preparation of MIPs and the magnetic nanospheres showed good application potential in fast separation, effective concentration and selective biosensing of large protein molecules.

Molecularly imprinted magnetic nanoparticles as tunable stationary phase located in microfluidic channel for enantioseparation

A microfluidic device integrated with molecularly imprinted magnetic nanoparticles as stationary phase was designed for rapid enantioseparation by capillary electrochromatography. The nanoparticles were synthesized by the co-polymerization of methacrylic acid and ethylene glycol dimethacrylate on 3-(methacryloyloxy)propyltrimethoxysilane-functionalized magnetic nanoparticles (25-nm diameter) in the presence of template molecule, and characterized with infrared spectroscopy, thermal gravimetric analysis, and transmission electron microscope. The imprinted nanoparticles (200-nm diameter) could be localized as stationary phase in the microchannel of microfluidic device with the tunable packing length by the help of an external magnetic field. Using S-ofloxacin as the template molecule, the preparation of imprinted nanoparticles, the composition and pH of mobile phase, and the separation voltage were optimized to obtain baseline separation of ofloxacin enantiomers within 195s. The analytical performance could be conveniently improved by varying the packing length of nanoparticles zone, showing an advantage over the conventional packed capillary electrochromatography. The linear ranges for amperometric detection of the enantiomers using carbon fiber microdisk electrode at +1.0 V (vs. Ag/AgCl) were from 1.0 to 500 microM and 5.0 to 500 microM with the detection limits of 0.4 and 2.0 microM, respectively. The magnetically tunable microfluidic device could be expanded to localize more than one kind of template-imprinted magnetic nanoparticles for realizing simultaneous analysis of different kinds of chiral compounds.

Flower-like self-assembly of gold nanoparticles for highly sensitive electrochemical detection of chromium(VI).

We report here the fabrication of a flower-like self-assembly of gold nanoparticles (AuNPs) on a glassy carbon electrode (GCE) as a highly sensitive platform for ultratrace Cr(VI) detection. Two AuNP layers are used in the current approach, in which the first is electroplated on the GCE surface as anchors for binding to an overcoated thiol sol-gel film derived from 3-mercaptopropyltrimethoxysilane (MPTS). The second AuNP layer is then self-assembled on the surface of the sol-gel film, forming flower-like gold nanoelectrodes enlarging the electrode surface. When functionalized by a thiol pyridinium, the fabricated electrode displays a well-defined peak for selective Cr(VI) reduction with an unusually large, linear concentration range of 10-1200 ng L(-1) and a low detection limit of 2.9 ng L(-1). In comparison to previous approaches using MPTS and AuNPs on Au electrodes, the current work expands the use of AuNPs to the GCE. Subsequent functionalization of the secondary AuNPs by a thiol pyridinium and adsorption/preconcentration of Cr(VI) lead to the unusually large detection range and high sensitivity. The stepwise preparation of the electrode has been characterized by electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM), and IR. The newly designed electrode exhibits good stability, and has been successfully employed to measure chromium in a pre-treated blood sample. The method demonstrates acceptable fabrication reproducibility and accuracy.

Enantioseparation and Amperometric Detection of Chiral Compounds by in Situ Molecular Imprinting on the Microchannel Wall

The molecular imprinting technique was first introduced into the microchannel of a microfluidic device to form in situ the imprinted polymer for fast enantioseparation of chiral compounds. The molecularly imprinted polymer (MIP) was in situ chemically polymerized on the microchannel wall using acrylamide as the functional monomer and ethylene glycol dimethacrylate as the cross-linker, and characterized by scanning electron microscopy, atomic force microscopy, and infrared spectroscopy. Under the optimized conditions, such as optimal preparation of MIP, composition and pH of mobile phase, and separation voltage, the model enantiomers, tert-butoxycarbonyl-D-tryptophan (Boc-D-Trp) and Boc-L-Trp, could be baseline separated within 75 s. The linear ranges for amperometric detection of the enantiomers using carbon fiber microdisk electrode at +1.2 V (vs Ag/AgCl) were from 75 to 4000 microM and 400 to 4000 microM with the detection limits of 20 and 140 microM, respectively. The MIP-microchip electrophoresis provided a powerful protocol for separation and detection of Boc-Trp enantiomers within a short analytical time. The molecular imprinting on microchannel wall opens a promising avenue for fast enantioscreening of chiral compounds.

Review: Bismuth complexes: synthesis and applications in biomedicine

A variety of bismuth complexes have been extensively explored in biomedical applications. The well-known low toxicity and environmental friendliness of bismuth salts make them valuable for large-scale synthesis of various bismuth-based complexes, which become more significant as active pharmaceutical ingredients of medical products. Bismuth complexes have been widely and preferably used in biomedicine with satisfactory therapeutic effect, which is highlighted in this review. However, their synthesis methods have been scarcely summarized. The classification of the main synthesis methods of bismuth complexes has been done here, followed by updates of the relevant advances concerning applications in biomedicine such as therapeutic effect on gastrointestinal diseases, antimicrobial, and anticancer activities, and the description of the side effect and biotoxicity resulting from long-term use of bismuth as well. Bismuth containing metal–organic frameworks, newly developed bismuth-based materials, are also discussed here, becoming a hot research topic recently. An outlook for future study on the potential use of bismuth complexes in biomedicine is provided in the end. This paper reviews the synthesis and biomedical applications of bismuth complexes with unusually low toxicity and excellent clinical performances, summarizes their main synthesis methods, and biomedical applications as drugs for the therapeutic treatment of gastrointestinal disease, Helicobacter pylori infection, and various cancers; especially, describes the development of bismuth-based MOFs in the drug delivery and potential application in cancer treatment.

Improved Bi film wrapped single walled carbon nanotubes for ultrasensitive electrochemical detection of trace Cr(VI)

We report here the successful fabrication of an improved Bi film wrapped single walled carbon nanotubes modified glassy carbon electrode (Bi/SWNTs/GCE) as a highly sensitive platform for ultratrace Cr(VI) detection through catalytic adsorptive cathodic stripping voltammetry (AdCSV). The introduction of negatively charged SWNTs extraordinarily decreased the size of Bi particles to nanoscale due to electrostatic interaction which made Bi(III) cations easily attracted onto the surface of SWNTs in good order, leading to higher quality of Bi film deposition. The obtained Bi/SWNTs composite was well characterized with electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), the static water contact angle and the voltammetric measurements. The results demonstrates the improvements in the quality of Bi film deposited on the surface of SWNTs such as faster speed of electron transfer, more uniform and smoother morphology, better hydrophilicity and higher stripping signal. Using diethylene triaminepentaacetic acid (DTPA) as complexing ligand, the fabricated electrode displays a well-defined and highly sensitive peak for the reduction of Cr(III)-DTPA complex at -1.06 V (vs. Ag/AgCl) with a linear concentration range of 0-25 nM and a fairly low detection limit of 0.036 nM. No interference was found in the presence of coexisting ions, and good recoveries were achieved for the analysis of a river sample. In comparison to previous approaches using Bi film modified GCE, the newly designed electrode exhibits better reproducibility and repeatability towards aqueous detection of trace Cr(VI) and appears to be very promising as the basis of a highly sensitive and selective voltammetric procedure for Cr(VI) detection at trace level in real samples.

Review: recent advances and future development of metal complexes as anticancer agents

Abstract Since the initial discovery of applications of platinum complexes in the clinical treatment of many kinds of cancers, the efficiency of platinum complexes in inhibiting the proliferation of various types of tumors surprised researchers working on the development of anticancer drugs. Meanwhile, despite the potent clinical treatment patients get from platinum complexes, there are also disadvantages including limited solubility in aqueous media and side effects like ototoxicity, myelosuppression, nephrotoxicity, and poor selectivity toward healthy cells. For this reason, efforts have been made to search for novel solutions. Non-platinum complexes (like Fe, Pd, Ru, Cu, Bi, Zn, etc.) were found with potential anticancer activities. We here review the properties of five metal complexes as anticancer agents and make comparisons among them in biological features and cytotoxic activity. Seeking the interrelation between microstructure and mechanism of anticancer, we hope this review provides distinct insights into future study of anticancer agents.

Potent anticancer activity of a new bismuth (III) complex against human lung cancer cells

The aim of this work is experimental study of an interesting bismuth(III) complex derived from pentadentate 2,6-pyridinedicarboxaldehyde bis(4N-methylthiosemicarbazone), [BiL(NO3)2]NO3 {L=2,6-pyridinedicarboxaldehyde bis(4N-methylthiosemicarbazone)}. A series of in vitro biological studies indicate that the newly prepared [BiL(NO3)2]NO3 greatly suppressed colony formation, migration and significantly induced apoptosis of human lung cancer cells A549 and H460, but did not obviously decrease the cell viability of non-cancerous human lung fibroblast (HLF) cell line, showing much higher anticancer activities than its parent ligands, especially with half maximum inhibitory concentration (IC50) <3.5μM. Moreover, in vivo study provides enough evidence that the treatment with [BiL(NO3)2]NO3 effectively inhibited A549 xenograft tumor growth on tumor-bearing mice (10mgkg-1, tumor volume reduced by 97.92% and tumor weight lightened by 94.44% compared to control) and did not indicate harmful effect on mouse weight and liver. These results suggest that the coordination of free ligand with Bi(III) might be an interesting and potent strategy in the discovery of new anticancer drug candidates.

Highly sensitive detection of hexavalent chromium utilizing a sol-gel/carbon nanotube modified electrode☆

A pyridine-functionalized thin film has been fabricated to selectively preconcentrate Cr(VI) anions for electrochemical detection in the 5-300 μg L-1 range. Glassy carbon electrodes were modified through physical deposition of single-walled carbon nanotubes (SWNTs) on the electrode surface, followed by electrochemical deposition of a sol-gel containing a 2-pyridine functional group. The use of SWNTs has increased sensitivity for Cr(VI) detection in aqueous solutions, providing a detection limit of 0.8 μg L-1.