Xiaoguang Wang

Antibacterial activity and cytocompatibility of Cu–Ti–O nanotubes

TiO2 nanotubes (NTs) have favorable biological properties, but the poor antibacterial activity limits their application especially in orthopedics fields. In this article, Cu-Ti-O nanotubes with different Cu contents are fabricated on sputtered TiCu films. Scanning electron microscopy reveals the NTs can be formed on sputtered TiCu films when the Cu content is less than 14.6 at %. X-ray photoelectron spectroscopy results indicate the NTs are consist of CuO mixed with TiO2 and the Cu content in NTs decreases dramatically compared with that in TiCu films. Biological experiments show that although these NTs have poor release antibacterial activity, their contact antibacterial activity has proven to be excellent, indicating the NT surface can effectively inhibit biomaterial-associated infections. The cytocompatibility of the NTs is closely related to the Cu content and when its content is relatively low (1.01 at %), there is no appreciable cytotoxicity. So Cu-Ti-O NTs with 1 at % Cu may be suitable to achieve proper antibacterial activity and desired cytocompatibility. The Cu-Ti-O NTs integrate the favorable antibacterial activity of Cu and excellent biological properties of TiO2 NTs therefore have potential applications in orthopedics, dentistry, and other biomedical fields.

Highly active carbon supported ternary PdSnPtx (x = 0.1–0.7) catalysts for ethanol electro-oxidation in alkaline and acid media

A series of trimetallic PdSnPtx (x=0.1-0.7)/C catalysts with varied Pt content have been synthesized by co-reduction method using NaBH4 as a reducing agent. These catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results show that, after adding a minor amount of Pt dopant, the resultant PdSnPtx/C demonstrated more superior catalytic performance toward ethanol oxidation as compared with that of mono-/bi-metallic Pd/C or PdSn/C in alkaline solution and the PdSnPt0.2/C with optimal molar ratio reached the best. In acid solution, the PdSnPt0.2/C also depicted a superior catalytic activity relative to the commercial Pt/C catalyst. The possible enhanced synergistic effect between Pd, Sn/Sn(O) and Pt in an alloyed state should be responsible for the as-revealed superior ethanol electro-oxidation performance based upon the beneficial electronic effect and bi-functional mechanism. It implies the trimetallic PdSnPt0.2/C with a low Pt content has a promising prospect as anodic electrocatalyst in fields of alkali- and acid-type direct ethanol fuel cells.

Matrix Stiffness in Three-Dimensional Systems Effects on the Behavior of C3A Cells

The purpose of this study was to evaluate in vitro how the modulation of stiffness in a three-dimensional (3D) system independently influenced the behaviors of hepatocytes. Cells of a human hepatocyte cell line, C3A, which have been used in a clinically tested bioartificial liver support system, were conducted as cell models. Using a 3D system of mechanically tunable alginate hydrogels, matrix stiffness was modeled by corresponding to values in normal and fibrotic livers. Through observing the cellular morphology, viability, functional protein analysis, and gene expression, the effect of the 3D matrix stiffness on C3A cells was investigated. When cultured in stiff hydrogels (12u2003Kpa), C3A cells adopt a growth arrested and dedifferentiated phenotype, whereas in soft hydrogels (1u2003Kpa), they remain differentiated phenotype. The behavior of C3A cells can be modulated via independent tuning of mechanical stimuli in the 3D alginate hydrogels, which is different from that in the two-dimensional (2D) systems. The results indicate the importance of matrix stiffness choice for liver tissue engineering.

Well-dispersed palladium nanoparticles on nickel- phosphorus nanosheets as efficient three-dimensional platform for superior catalytic glucose electro-oxidation and non-enzymatic sensing

In this work, we report a novel well-dispersed palladium nanoparticles (PdNPs)/nickel-phosphorus nanosheets (Ni-P NSs) synthesized by combination of red phosphorous phosphorization and simple electrodeposition technique. The obtained PdNPs/Ni-P nanosheets framework with large electrochemical active surface would not only exhibit much superior electrocatalytic activity (180.5±3.07mAcm-2) toward glucose oxidation reaction, but also represent a wide linear range (2μM-4.65mM) and high sensitive detection of glucose (242.5±3.28μAmM-1cm-2) as non-enzymatic glucose sensor. The three- dimensional (3D) PdNPs/Ni-P nanosheets have a promising prospect as a novel kind of highly active nanocatalyst and non-enzymatic electrochemical sensor.

Self-Supported Ternary Ni–S–Se Nanorod Arrays as Highly Active Electrocatalyst for Hydrogen Generation in Both Acidic and Basic Media: Experimental Investigation and DFT Calculation

In this study, a novel three-dimensional self-supported ternary NiS-Ni9S8-NiSe nanorod (NR) array cathode has been successfully in situ constructed by a two-step hydrothermal route. When applied to hydrogen evolution, the synthesized NiS-Ni9S8-NiSe-NR electrode demonstrates optimized electrocatalytic activity and long-term durability, only requiring overpotentials as low as 120 and 112 mV to drive 10 mA cm-2 for hydrogen evolution reaction in 0.5 M H2SO4 and 1.0 M KOH, respectively. Density functional theory calculation reveals that after Se doping Se 3d orbitals are bonded to Ni 3d orbitals and S p orbitals near Fermi level, attesting a significant electron transfer between nickel and selenium atoms. The success of enhancing the electrocatalytic performance via introducing the Se dopant holds great promise for the potential optimization of other transition-metal compounds in highly efficient electrochemical water splitting for large-scale hydrogen production.

FACILE SYNTHESIS OF Pt-/Pd-MODIFIED NiTi ELECTRODE WITH SUPERIOR ELECTRO-CATALYTIC ACTIVITIES TOWARD METHANOL, ETHANOL AND ETHYLENE GLYCOL OXIDATION

Surface functional modification of NiTi electrode with noble Pt and Pd metal has been successfully carried out by simple and cost effective electro-spark deposition technique (ESD). Thin-film X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and cyclic voltammetry (CV) have been carried out in order to investigate the structure, morphology, chemical composition and electrochemical behavior of the modified electrode surface. The modified Pt/NiTi and Pd/NiTi electrode surface exhibit a circular splash pattern with a tiny amount of Pt (∼5.30 at.% Pt) and Pd (∼5.71 at.% Pd) existence. The electrochemical results demonstrate that the Pt/NiTi and Pd/NiTi electrode possess an improved electro-catalytic activities toward methanol (MeOH), ethanol (EtOH) and ethylene glycol (EG) oxidation in alkaline media in comparison with the bare NiTi electrode. In acidic environments, the Pt/NiTi electrode exhibits even much better catalytic activities than the pure Pt sheet electrode due to the bi-functional mechanism. In the same way, the electro-catalytic activity of the modified Pd/NiTi electrode is also slightly larger than that of the pure Pd sheet electrode in alkaline environment. The electro-spark surface modification approach is rapid and environmentally-benign, being attractive to widen the application of traditional surface modification technique in the field of material surface/interface design and functionalization.