Liangzhuan Wu

Non-enzymatic glucose detection using as-prepared boron-doped diamond thin-film electrodes

Electrochemical oxidation of glucose in alkaline solution at as-prepared boron-doped microcrystalline diamond (BDMD) and nanocrystalline diamond (BDND) thin-film electrodes is investigated by cyclic voltammetry. The results demonstrate that glucose can be directly oxidized at as-prepared boron-doped diamond (BDD) thin-film electrodes and the curve of the negative scan traces onto the positive scan. The effect of sodium hydroxide concentration on the response of glucose is also studied in the range of 0.02-0.6 M and the optimum concentration of sodium hydroxide is found to be 0.1 M. The voltammetric signal of glucose and the mixture of ascorbic acid (AA) and uric acid (UA) can be observed well-separated at as-prepared BDD thin-film electrodes in 0.1 M sodium hydroxide solution. The peak current is proportional to the glucose concentration in the range 0.25-10 mM with a correlation coefficient of 0.9993 in the presence of AA and UA. Furthermore, the experiment results also show that the non-enzymatic glucose sensor based on as-prepared BDD thin-film electrodes has high sensitivity, good reproducibility and stability.

Fabrication of micropatterned ZnO/SiO2 core/shell nanorod arrays on a nanocrystalline diamond film and their application to DNA hybridization detection

Micropatterned ZnO/SiO2 core/shell nanorod arrays are successfully fabricated on nanocrystalline diamond (NCD) film surfaces, and their performance as a fluorescence signal enhancing platform for DNA hybridization detection is also investigated. The fabrication process, from oriented ZnO nanorod deposition, amine silanation, and attachment of a biofunctional cross-linking molecule to the covalent immobilization of probe oligonucleotides, is defined. X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize ZnO/SiO2 core/shell nanorods. The sequence complementary and stability of the DNA-modified surface are demonstrated in hybridization experiments. The use of ZnO/SiO2 nanorod arrays not only greatly enhances the fluorescence signal collected but also decreases the nonspecific adsorption effect of ZnO nanomaterials after carrying out the hybridization reaction.

Diamond Nanowires: Fabrication, Structure, Properties, and Applications

C(sp(3) )C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Youngs modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications.

Low-temperature and one-step synthesis of rutile TiO2 aqueous sol by heterogeneous nucleation method

A phase-pure rutile TiO(2) aqueous sol has been prepared by heterogeneous nucleation method with an aqueous peroxotitanate solution as a precursor and SnCl(2) as rutile-phase crystalline growth promoter at a temperature as low as 100 °C in one-step process. TEM, XRD and UV-Vis spectra were used to characterize the rutile TiO(2) sol. The results reveal that a pure rutile phase TiO(2) aqueous sol with average particle sizes of around 20 nm has been synthesized, and a transparent film of rutile TiO(2) was also easily prepared by dip-coating method. Formation conditions and a possible mechanism of phase-controlling were investigated. The results show that the presence of the Sn content is essential for the formation of a pure rutile TiO(2) phase at low temperature, which involves a heterogeneous nucleation mechanism.

Large scale fabrication of highly monodispersed rattle-type TiO2@void@SiO2 spheres via synthesis-cum-organization process.

Architected nanostructures with interior space have attracted enormous attention due to both their esthetic beauty and their potential applications. It is a current dream to develop a template-free, one-pot and low-temperature synthetic routes for hetero-architecture in liquid media. In this manuscript, we develop a kind of template-free, low-temperature, and one-pot total synthetic strategy for synthesis of inorganic multi-component hetero-architecture. This synthetic strategy analogous to standard organic reactions used in total synthesis is an important breakthrough in inorganic chemical synthesis. We can achieve 1 kilogram (kg) yield of the TiO(2)@void@SiO(2) core-shell sphere one time by using this synthetic strategy, which may lead to practical applications of the sample. By embodying the new reaction and concept into future investigation, a more mature research field in synthetic architecture of nanomaterials can be anticipated.

Low cost and large-area fabrication of self-cleaning coating on polymeric surface based on electroless-plating-like solution deposition approach

A novel low-cost controllable solution-based coating process for realization of self-cleaning coating on large-area flexible polymeric substrates based on an improved Electroless-Plating-Like Solution Deposition (EPLSD) approach was developed. In a typical coating procedure, a layer of aniline was first adsorbed onto the surface of a flexible polymeric substrate by dip-coating; and as the pretreated flexible substrate was then immersed into an nanosol including a Peroxo-Titanium-Complex (PTC) modified silica (P–Si), after the thermal treatment at 80 °C for 30 min, the flexible polymeric substrate coated by P–Si composite thin films could be obtained. The as-prepared TiO2–SiO2 thin film was characterized by TEM, SEM, XRD, and FTIR analysis, and its self-cleaning characteristics were also evaluated by the contact angle and the methyl blue degradation test.

Bacillus subtilis-based colorimetric bioassay for acute biotoxicity assessment of heavy metal ions

This paper described a novel colorimetric bioassay based on Bacillus subtilis for acute biotoxicity assessment of heavy metal ions and real water samples. β-Galactosidase, which can catalyze the hydrolysis of o-nitrophenyl-β-D-galactopyranoside (ONPG) to produce galactose and o-nitrophenol (ONP), can be generated from Bacillus subtilis (CGMCC 1.1086) without the assistance of any inducers. When heavy metal ions exist, the activity of β-galactosidase is inhibited due to the reaction between the sulfhydryl groups in β-galactosidase and the heavy metal ions. Accordingly, the output of the ONP, a yellow chromogenic compound exhibiting a characteristic absorption peak at 420 nm, is also inhibited. Thus, acute biotoxicity of heavy metal ions can be evaluated by assessing the absorption intensity of ONP at 420 nm. To obtain an ideal colorimetric performance, working parameters such as Bacillus subtilis concentration, temperature and incubation time of the bioassay were studied and optimized. Under the optimized parameters, the acute biotoxicity of five heavy metal ions (Cu2+, Zn2+, Ni2+, Cd2+, Pb2+) and three real samples were evaluated. All the results suggest that Bacillus subtilis-based bioassay is a sensitive, economic, simple and promising alternative for acute biotoxicity assessment.

M⧹TiO2 (M = Au, Ag) transparent aqueous sols and its application on polymeric surface antibacterial post-treatment

In this paper, we reported a simple and mild chemical method for synthesis of crystalline metal\TiO2 (M=Au, Ag) transparent aqueous sols at low temperature (80°C). It should be found that the as-synthesized metal\TiO2 sols could easily be coated on the flexible PET surfaces of the through the as-developed electroless-plating-like solution deposition (EPLSD) procedure. The as-prepared metal\TiO2 sols and related flexible thin film were characterized by TEM, SEM, XRD, UV-vis, and FTIR analysis. The results showed that the Au and Ag nanoparticles can significantly improve the optical absorption properties of TiO2 due to the surface plasmon generated by the noble metal, which in turn enhanced the photo-induced antibacterial performance of the as-prepared metal\TiO2 flexible film. Moreover, the photo-generated electrons could transfer between the metal and titanium dioxide under different irradiation (ultraviolet or visible light), which could significantly reduce the recombination of photo-induced electrons and holes, resulting in the better photo-induced antibacterial performance. Therefore, the EPLSD procedure may be used as a general polymeric surface antibacterial post-treatment procedure for preparing the metal\TiO2 flexible film because of the noble metal enhanced antibacterial performance.

Light-assisted oriented attachment process for ultrathin vanadium pentoxide nanosheets with intensive room-temperature photoluminescence emission

An ultrathin vanadium pentoxide nanosheets colloid has been synthesized using peroxovanadium coordination compound (PVC) as a precursor through a simple, light-assisted aqueous-phase synthetic strategy. The μ-chelated triangle structured radicals, obtained by selective decomposition of the PVC precursor under UV irradiation, can limit the condensation process proceeding only within the ab plane, leading to a planar nanopieces intermediate in the initial stage of the refluxing reaction. Ultrathin vanadium pentoxide nanosheets were then formed through the oriented attachment processes of the initially formed small vanadium oxide nanopieces. The as-synthesized vanadium pentoxide nanosheets exhibited an unusual room-temperature photoluminescence emission, which can be attributed to the quantum size effect associated with their ultrathin thickness.

An electroless-plating-like solution deposition approach for large-area flexible thin films of transition metal oxide nanocrystals

We developed a novel Electroless-Plating-Like Solution Deposition (EPLSD) approach for realization of large-area flexible thin films of transition metal oxides (TMOs) with d0 configuration. This EPLSD approach was triggered at 80 °C through the redox reaction between Peroxo-Metal Complex (PMC, including Peroxo-Titanium Complex (PTC), Peroxo-Vanadium Complex (PVC), and Peroxo-Molybdenum Complex (PMoC)) and organic conductive electroactive monomers (EDOT, pyrrole, and aniline). In the typical EPLSD process, a layer of organic conductive electroactive polymer monomers was absorbed onto the surface of the flexible polymer substrate by dip coating, and these pretreated flexible substrates were then immersed into an aqueous PMC solution for the EPLSD process. After the EPLSD process at 80 °C for 30 min, large area (40 cm × 300 cm) flexible thin films of metal oxide nanocrystals, including TiOx, VOx, and MoOx, nanocrystal films can be achieved. This low-temperature EPLSD process is advantageous for flexible substrates and may easily realize TMO films on flexible substrates with different geometric shapes.