PubMed Health⌕ Search

Biomedical subjects

Wensheng Yang

Publications and source records attributed to Wensheng Yang.

At least 19 recordsLinked to original sources
PubMed2007

Effect of silica nanoparticles with different sizes on the catalytic activity of glucose oxidase.

In this work we present a strategy for the covalent immobilization of periodate oxidized glucose oxidase (IO(4)(-) - GOx) to aminated silica nanoparticles (ASNPs) modified on gold electrodes. Silica nanoparticles greatly enhanced the catalytic ability of GOx toward the oxidation of glucose and improved the electron transfer between the GOx and the electrode surface. ASNPs of varying size--that is 100, 80, 60, and 30 nm--were prepared, and they were used to fabricate biosensors. Electrochemical impedance spectroscopy (EIS) of ferrocyanide followed the assembly process and verified the successful immobilization of IO(4)(-) - GOx on ASNPs modified on gold electrodes. From the analysis of catalytic signals of biosensors using different sizes of ASNPs under the same conditions, the surface concentration of electrically wired enzyme (Gamma (ET)) was estimated and was found to increase with decreasing ASNPs size. Therefore, the sensitivity of biosensors using smaller ASNPs was higher than that using larger particles. Specifically, we utilized the ASNPs with optimal size (30 nm) to fabricate the glucose biosensor. The resulting electrodes showed a wide linear response to glucose at least to 6 mM and reached 95% of the steady-state current in less than 4 s with a sensitivity of 5.02 microA mM(-1) cm(-2) and a detection limit of 0.01 mM. The biosensor also showed excellent stability and good reproducibility.

Amination↗
PubMed2006

CARPs are ubiquitin ligases that promote MDM2-independent p53 and phospho-p53ser20 degradation.

Caspase 8/10-associated RING proteins (CARPs) are a recently described family of protein ubiquitin ligases that interact with and negatively regulate death receptor-mediated apoptosis. Because CARPs are overexpressed in cancer and their silencing reduces cell viability and sensitizes tumor cells to chemotherapeutic agents, we investigated their relationship to p53 tumor suppressor signaling. p53 is a major determinant of chemosensitivity, and its levels are increased following DNA damage through N-terminal phosphorylation and inhibition of degradation. Although p53 is well known to be negatively regulated by several ubiquitin ligases including MDM2, none are known to target phosphorylated p53 for degradation. CARPs physically interact with and ubiquitinate p53, targeting it for degradation in the absence of MDM2. Serine 20-phosphorylated p53 is also ubiquitinated by CARPs. CARP silencing stimulates p53 expression and promotes downstream effects, including transcriptional activation and tumor suppression.

Animals↗
PubMed2006

A simple hydrothermal method for the large-scale synthesis of single-crystal potassium tungsten bronze nanowires.

The large-scale synthesis of single-crystal K(x)WO(3) tungsten bronze nanowires has been successfully realized by a hydrothermal method under mild conditions. Uniform K(0.33)WO(3) nanowires with diameters of 5-25 nm and lengths of up to several micrometers are obtained. It is found that the morphology and crystallographic forms of the final products are strongly dependent on the sulfate and citric acid, which may act as structure-directing and soft-reducing agent, respectively. Some other influential factors on the growth of tungsten bronze nanowires, such as temperature and reaction time, are also discussed. It is worth noting that other alkali metal tungsten bronzes such as (NH(4))(x)WO(3), Rb(x)WO(3), and Cs(x)WO(3) could also be selectively synthesized by a similar route. Thus, this novel and efficient method could provide a potential mild route to selectively synthesize various tungsten bronze on-dimensional nanomaterials.

Journal Article↗
PubMed2006

Great enhancement of photocatalytic activity of nitrogen-doped titania by coupling with tungsten oxide.

The TiO2-N-x%WO3 composite photocatalysts were prepared by introducing WO3 into nitrogen-doped TiO2. The composite catalysts present much higher photocatalytic activity than TiO2 and nitrogen-doped TiO2 under both ultraviolet and visible light irradiation. Diffuse reflectance UV-vis spectra, XPS analysis, and IR spectra show that the coordinated nitrogen species (or N-metal-O linkages) may contribute to the visible light photocatalytic activity. WO3 coupling increases the active nitrogen species and thus enhances the visible light activity of the composite photocatalysts. The superior activity of TiO2-N-x%WO3 composite photocatalysts upon UV light irradiation can be rationalized in terms of efficient charge separation and high adsorption affinity of WO3.

Journal Article↗
PubMed2006

Evidence of a unique electron donor-acceptor property for platinum nanoparticles as studied by XPS.

In the interaction of PVP with Pt nanoparticles <7 nm in size, charge transfer is from carbonyl groups in PVP to Pt nanoparticles, whereas in the interaction of PVP with bulk Pt or Pt nanoparticles >25 nm in size, charge transfer is from Pt metal to the polymer side chain of PVP. There exists a critical nanoparticle size between 7 and 25 nm that would lead to a switch in the electron donor-acceptor property.

Journal Article↗
PubMed2006

Multilayered construction of glucose oxidase and silica nanoparticles on Au electrodes based on layer-by-layer covalent attachment.

A feasible approach to construct multilayer films of aminated silica nanoparticles/glucose oxidase (ASNPs/GOx) on the Au electrode surface using a glutaraldehyde as a covalent attachment cross-linker is described. The covalent attachment processes were followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrated that the ASNPs/GOx multilayer films are formed in a progressive and uniform manner. The gold electrodes modified with the ASNPs/GOx multilayer films were studied by cyclic voltammetry (CV) and showed excellent electro-catalytical response to the oxidation of glucose when ferrocenemethanol was used as an artificial redox mediator. From the analysis of voltammetric signals, the coverage of active enzyme on the electrode was estimated, which showed a linear relationship with the number of ASNPs/GOx bilayers. This suggests that the analytical performance such as sensitivity, detection limit is tunable by controlling the number of attached bilayers. The linear response range of the biosensor constructed with four bilayers of ASNPs/GOx to the concentration of glucose can extend at least to 8mM and reached 95% of the steady-state current in less than 4s with the sensitivity of 5.11 microA/mM cm(2) and the detection limit of 9 microm. In addition, the sensor exhibited good stability and long-term life.

Biosensing Techniques↗
PubMed2005

Population data for 11 Y-chromosome STRs in northeast China Han.

Allele and haplotype frequencies for the 12 Y-specific short tandem repeats (STR) loci DYS19, DYS385a/b, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438, DYS439 (PowerPlex Y System STR Amplification Kit, Promega) were determined in a population sample of 187 unrelated China Han in northeast China.

China↗
PubMed2005

Population data for the AmpFl STR Identifiler PCR Amplification Kit in China Han in Jilin Province, China.

Allele frequencies for the fifteen short tandem repeats (STR) loci D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, D19S433, THO1, D16S539, CSF1PO, TPOX, D2S1338 (AmpFl STR Identifiler PCR Amplification Kit, Applied Biosystems) were determined in a population sample of unrelated China Han in Jilin Province, China. Statistical analyses were performed using Powerstats version 1.2 and GEP-ISFGWG. The results showed that all the loci met Hardy-Weinberg expectation.

China↗
PubMed2005

Nanotubes from isomeric dibenzoylmethane molecules.

Organic nanotubes of various diameters were fabricated from the isomeric molecule dibenzoylmethane (DBM) by using an immersing technique with ordered porous alumina membrane as the template. The ratio of the enol isomers of DBM increased as the diameters of the nanotubes decreased. In addition, although almost no fluorescence could be detected for the DBM monomer, a striking enhancement in the fluorescence emission intensity of the nanotubes was observed as the diameters decreased. This is due to the increased ratio of the enol isomers.

Chalcones↗
PubMed2004

Size-dependent exciton chirality in (R)-(+)-1,1'-bi-2-naphthol dimethyl ether nanoparticles.

Organic nanoparticles from a chiral auxiliary, (R)-(+)-1,1'-bi-2-naphthol dimethyl ether (BNDE), with a range of particle sizes from 25 to 100 nm were fabricated through the reprecipitation method. It is found that BNDE nanoparticles exhibit positive exciton chirality in 200-260 nm region in circular dichroism (CD) spectra, which are completely opposite to CD spectra of the dilute solution. The exciton chirality of the particles displays size-dependent behavior; that is, the exciton chirality peaks evolve to the low-energy side with increase in particles size. CD spectra accompanied with UV, fluorescence spectra, lifetime measurements of the excited states, and quantum mechanical calculations reveal that the chirality inversion results from intermolecular exciton coupling between two adjacent BNDE molecules in the nanoparticles, and the bathochromic shift of the peaks is attributed to the increased intermolecular interaction with increasing particle size.

Journal Article↗
PubMed2004

Comparison between the effects of TiO2 synthesized by photoassisted and conventional sol-gel methods on the photochromism of WO3 colloids.

WO3 colloids can exhibit a blue color under UV-light irradiation due to the absorption of electrons trapped at the energy levels within the forbidden gap and this coloration performance can be improved by TiO2 nanoparticles. In this work, it is found that TiO2 prepared by the photoassisted method (TiO2-P) exhibits stronger enhancement effects than that prepared by the conventional sol-gel method (TiO2-C). Several possible mechanisms have been proposed to account for this phenomenon. The migration of charge carriers toward different directions is promoted since the flat-band potential of TiO2-P colloids is more negative than that of TiO2-C and the contact between WO3 and TiO2 particles is improved in the WO3/TiO2-P system; there are more efficient TiO2 and hole scavengers (i.e., Ti3+ and/or TiO2-O2*- species) in the system containing TiO2-P; the bandgap of TiO2-P becomes narrowed, and so on. In addition, the potential applications of this process are also discussed briefly.

Absorption↗
PubMed2003

Size-tunable emission from 1,3-diphenyl-5-(2-anthryl)-2-pyrazoline nanoparticles.

Organic nanoparticles of 1,3-diphenyl-5-(2-anthryl)-2- pyrazoline (DAP) ranging in average diameters from 40 to 160 nm were prepared through the reprecipitation method. The average diameters of the particles were controlled by variation of the aging time. We found that DAP nanoparticles exhibit the size-dependent optical properties. The absorption transitions of the nanoparticles at the lower-energy side experience a bathochromic shift with an increase in the particle size as a result of the increased intermolecular interactions, while the higher-energy bands of anthracene split possibly due to the electronic coupling between the pyrazoline ring of one molecule and the anthracene moiety of the neighboring molecule. Most interestingly, the nanoparticle emission in the blue light region from pyrazoline chromophore shifts to shorter wavelengths with an increase in the particle size, accompanied with a relatively gradual dominance of the emission at about 540 nm from an exciplex between the pyrazoline ring of one molecule and the anthracene moiety of the neighboring molecule. The hypsochromic shift in the emission of DAP nanoparticles was identified as originating from the pronounced decrease in the Stokes shift due to the restraint of vibronic relaxation and the configuration reorganization induced by the increased intermolecular interaction.

Journal Article↗
PubMed2003

Chromosomal location, structure, and temporal expression of the platelet-activating factor receptor (PAFr) gene in porcine endometrium and embryos relative to estrogen receptor alpha gene expression.

Although platelet-activating factor receptor (PAFr) gene was well characterized in the human, little was known about it in domestic animals. Porcine PAFr gene was mapped using fluorescence in situ hybridization (FISH). The structure of this gene was investigated using a 5' rapid amplification of cDNA ends (RACE) technique. Temporal expression of PAFr and estrogen receptor alpha genes (ER), and distribution of the PAFr transcripts in porcine endometrial and embryonic tissues on days 0, 10, 12, 14, 16, and 18 were analyzed using DNA competitors and reverse transcription and polymerase chain reaction (RT-PCR). The porcine PAFr gene was mapped to SSC6q26-27. Alternative splicing of primary transcripts of the PAFr gene produced two different transcripts. Transcript 1 was expressed in all tissues and cells, and transcript 2 was detected in all tissues but white blood cells. The temporal expression of the PAFr gene in endometrial (P > 0.05) and embryonic (P < 0.05) tissues of pregnant sows increased from day 10 to 16. The temporal expression of ER genes in endometrial tissues of pregnant sows decreased from day 10 to 18 (P < 0.05). In addition, ER expression was detectable in 20-60% of embryonic tissue samples, which generally decreased. In combination with previously obtained data on PAF and estradiol-17beta (E(2)) concentrations in pregnant uterine luminal fluids (pULF), endometrial and embryonic tissues, the present results indicated that the increasing PAFr transcripts were positively associated with increasing levels of PAF. Both ER transcripts and E(2) found in pULF decreased correspondingly from day 13 to 16. These results indicate that via PAFr, PAF could play a dominant role in peri-implantation development in pigs as compared to E(2).

Animals↗