Papers by Author: Wen Jian Weng

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Authors: Yan Bao Li, Dong Xu Li, Wen Jian Weng
Abstract: Biphasic tricalcium phosphate (BTCP) powders composed of α-tricalcium phosphate (α-TCP) and β-tricalcium phosphate (β-TCP) were prepared using amorphous calcium phosphate (ACP) precursor after heat treatment at 800oC. The in vitro dissolution behavior of the powders was examined after soaked in 0.1M NaAc-HAc buffer solution for different times. It was revealed that the Ca2+ and PO4 3- concentration, and pH value of the BTCP-soaked solution are higher than those of the α-TCP- and β-TCP-soaked solutions. The dissolution behavior of BTCP powders was explained. The specific dissolution behavior of BTCP powders can widen the biodegradation range of calcium phosphate family.
Authors: Shun Dong Miao, Wen Jian Weng, Kui Cheng, Chen Lu Song, Pi Yi Du, Gao Ling Zhao, Ge Shen, Jian Xun Wang, Gao Rong Han
Abstract: Nano-sized zinc containing β-tricalcium phosphate (ZnTCP) powders were synthesized by a co-precipitation method. The co-precipitation took place in an ice-water bathed beaker, after further washing, freezing, lyophilizing and calcining at 800°C, the precipitates transformed to ZnTCP powders. The XRD pattern of the ZnTCP powders demonstrated a pure β-TCP phase. TEM observation revealed the particle size is about 100-120nm, which is favorable for TCP particles to form composites, such as polymer based composite, and as well to attain a desired microstructure. It was found zinc incorporation could eventually result in the decrease of particle size, thus be beneficial for its further application.
Authors: Wei Qi Yan, Xin Huang, Xiao Chun Zhong, Shun Dong Miao, Wen Jian Weng, Kui Cheng
Authors: Bing Gang Guan, Wei Qi Yan, Di Sheng Yang, Chao Zou, Wen Jian Weng
Abstract: A novel porous beta-tricalcium phosphate /collagen fibers (β-TCP/CF) composite, having a well-dispersed nano-sized β-TCP in collagen matrix, was developed by a wet-chemical method. The nano-composite was compared to conventional β-TCP on cytocompatibility by cell attachment, proliferation, alkaline phosphotatse (AKP) activity and scanning electron microscopy (SEM) analysis. These in vitro assays showed that the β-TCP/CF composite elicited cell adhesion and proliferation better then controls. Moreover experiments on osteoblast-like cells showed improved cell growth with the highly characterized nanophase structure. SEM micrographs also showed that the nano-sized composite exhibited much more viable cells in attachment on the surface compared with the controls. At 1, 3 and 5 days, AKP activity was not significant different for the tested and control samples, while at 7 day after culture, significantly increased AKP activity was observed for β-TCP/CF than for the control. The in vitro results obtained confirmed the remarkable improvement of cell adhesion and proliferation of the nano-sized β-TCP/CF composite, which may be a new promising candidate for tissue engineered bone substitute.
Authors: Rui Bing Wang, Wen Jian Weng, Xu Liang Deng, Kui Cheng, Xing Gang Liu, Pi Yi Du, Ge Shen, Gao Rong Han
Abstract: Submicron α-tricalcium phosphate (α-TCP), β-tricalcium phosphate (β-TCP) and biphasic α/β-TCP powders were prepared by an amorphous calcium phosphate (ACP) precursor way. For the biphasic TCP powders, primary particle size was 300nm, α-TCP and β-TCP primary particles were homogeneously mixed in the submicron powders. When the TCP powders were soaked in acetate buffer solution with pH 5, the Ca ion concentration in the soaked solutions and the resulting morphology variations were measured and observed. The results showed that the dissolution behavior of the biphasic TCP powders was different from α-TCP and β-TCP, and had a higher dissolved Ca ion concentration. This is attributed to a high supersaturation which is cased by the distribution homogeneity of two phase primary particles in submicron powders. These demonstrate the biphasic TCP to have potential to extend biological applications of Ca phosphates.
Authors: Bing Gang Guan, Di Sheng Yang, Zhong Li Shi, Wen Jian Weng, Wei Qi Yan
Abstract: A novel biomimetic composite consisted of nano β-tricalcium phosphate and collagen (n-TCP/Col.), having similar structure with the natural bone, was produced by a wet-chemical method. The biological effect with and without n-TCP/Col on bone repair and regeneration was evaluated by histological and radiological examination in a rabbit femoral condyle model. The results showed that radiopacity of implant decreased gradually and began to increase at 12 weeks, while no obvious changes for the control. Histological results revealed that trabecular bone formed around the implant at 4 weeks and increased at 8 weeks; By 12 weeks, bone filling with Harvard’s system was observed around the implant. By contrast, only loose connective tissue was seen in control group. This was further illuminated by fluorescence microscopy. The results of this study suggested that the novel nano β-tricalcium phosphate and collagen composite possessed good properties of osteoconductivity and degradation in the biological environment, which could have potential application as a promising bone substitute.
Authors: Zhong Ru Gou, Wen Jian Weng, Chao Zou, Pi Yi Du, Gao Rong Han
Abstract: The gelation process is of importance for the structure and texture of the silica particle and further functionalization in the area of biomedical application. In a base-catalysis process the sodium phosphate or plus calcium nitrate salts could be added to induce the gelling velocity and particle size distribution. Multivalent anions (phosphate ions) or dication (calcium ions) induce the microscopic phase separation and accelerate gelation of silica sol. Furthermore, the composite silica nanospheres show excellent monodispersibility as well as pH-stability in the simulated body fluids or Tris-HCl buffer solution, which will help to surface modification and functionalization in the biomolecule-existing environments.
Authors: L.W. Tang, Pi Yi Du, Wen Jian Weng, Gao Rong Han
Abstract: Silver dispersed lead titanate films were prepared with different Pb/Ti ratio precursors. The influence of lead excess in precursor on the formation and dielectric properties of silver-dispersed lead titanate film was investigated. Firstly, Pb excess in precursor will eliminate the formation of pyrochlore PbTi3O7 and increase c/a ratio of perovskite PbTiO3. Secondly, excessive Pb will react with silver, and they can produce volatile product, which evaporate during heat treatment process. The volatility of the reaction product varies with the increase in lead excess. When lead excess is low (Pb/Ti=1.1), volatility of reaction product is high. At this time, only small amount of silver remain in the film. The remanent silver aggregate to form small silver particles. When lead excess is high (Pb/Ti=1.2 and Pb/Ti=1.3), volatility of reaction product gradually becomes poor. At this time, the content of remanent silver in the film increase with the increase in lead excess. Compared with the film prepared with low Pb/Ti ratio, the dispersive degree of silver in film prepared with high Pb/Ti ratio is higher. Due to the decrease of remanent silver content in the film, dielectric constant and dissipation factor both decrease when Pb/Ti initially increase from 1 to 1.1. And after that, dielectric constant and dissipation factor both increase with the addition of excessive Pb in precursor, due to the increase in the content and dispersion degree of silver, and increase in c/a ratio of PbTiO3 lattice with the addition of excess Pb. The film prepared with appropriate excessive lead (Pb/Ti=1.3) precursor expresses higher dielectric constant and lower dissipation factor than the film prepared with stoichiometric Pb/Ti ratio.
Authors: Rong Wu, Pi Yi Du, Wen Jian Weng, Gao Rong Han
Abstract: BST/PLT composite thick films with various content of PbO-B2O3 glass additive from 5mol% to 25mol% were successfully prepared by screen-printing the paste onto alumina substrates. XRD, SEM and impedance meter were used to analyze the phase structures, morphologies and dielectric properties of the thick films. The results showed that the BST phase has no interaction with PbO-B2O3 glass in the composite thick films at 750 oC. Diffusion between PLT phase and PbO-B2O3 glass phase occurs and the c axis of PLT phase in thick films reduces slightly. The high infiltration between the glass phase and particles densify the composite thick films and the uniform microstructure can be obtained in the thick films with PbO-B2O3 glass additive content of 10mol%. Good temperature stability of dielectric properties is achieved with the 25mol% content of PbO-B2O3 glass additive and the variance of the relative dielectric constant in the temperature range between 0oC and 300oC is 15%.
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