Papers by Author: Zhong Wei Gu

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Authors: Chao Yong Zhao, Hu Li, T. Yuan, Hong Song Fan, Xing Dong Zhang, Zhong Wei Gu
Abstract: This study was carried out to investigate the effect of acid-alkali treatment and alkaliheat treatment on the push-out strength and tissue response of the porous titanium in vivo. Porous titanium with different treatment was implanted in dog bony site for 2 months and 5 months and the push-out strength was tested. At 2 months, the mean push-out strengths of the acid-alkali treated and alkali-heat treated porous titanium were 11.3 and 15 MPa, respectively. At 5 months, the values reached 29.8 and 35 MPa, respectively. Histological observation showed a close contact between implants and bone, and more bone tissue filled inside the pores of porous titanium increasing with implantation time. The results indicated higher bonding strength between bone and porous titanium in alkali-heat treated samples. Therefore, alkali-heat treatment can provide porous titanium implants with better fixation as a bone substitute for clinical use under load-bearing conditions.
Authors: Yi Wang, Hong Song Fan, Yu Mei Xiao, Zhong Wei Gu, Xing Dong Zhang
Abstract: A new way to prepare polymer/hydroxyapatite(HA) composite scaffolds with 3-D interconnected macro and micro pores at room temperature was established, basically based on solvent-casting and particle-leaching together with foaming technique. With this method, Polylactide (PLA) / HA composites of porous architecture with macro pores (50~300)m, average 200)m) and micro pores (~10)m) on the skeleton were obtained. The bending strength and the compressive strength of the composite scaffold were reached to 11.5 MPa and 7MPa respectively with the porosity of approximate to 90%. The study supplied a new short time, low energyexpending method to prepare polymer/ceramic composite with high porosity and interconnected porous structure at room temperature.
Authors: Yu Mei Xiao, Xu Dong Li, Hong Song Fan, Xiang Dong Zhu, Li Zhao Teng, Zhong Wei Gu, Xing Dong Zhang
Abstract: Good interfacial interaction is crucial for preparation of inorganic-organic materials at a nanometer level. Poly(α-methacrylic acid) (PMAA) was grafted on the PLA surfaces via photooxidization and subsequent UV induced polymerization in an attempt to synthesize nano-hydroxyapatite/poly(lactide) (n-HA/PLA) composites. Grafting of PMAA on the PLA surface was confirmed using FTIR analysis and the size distribution measurement of the grafted-PLA (g-PLA) particles. n-HA/g-PLA composites were in situ synthesized via dropwise addition of Ca2+- and g-PLA containing solution to PO4 3-- solution. The prepared composites were characterized by FTIR, XRD,SEM and TEM means. Analytical results indicated that the g-PLA acts as a template to manipulate the nucleation and growth of n-HA crystals and thereby to control the morphology, size and anisotropy of n-HA crystals and their distribution over the organic phase. Chemical linkages and/or interfacial interactions between the n-HA and the g-PLA in the n-HA/g-PLA composite were further discussed.
Authors: Bo Jiang, Zhi Hong Wu, Jing Ying Zeng, Jian Lu, Qing Rong Wei, Xing Dong Zhang, Zhong Wei Gu
Abstract: Collagenous molecule was successfully immobilized to hydroxyapatite (HA) surface through a molecular bridge (2-Hydroxyethyl acrylate, HEMA) that was grafted to the surface with covalent bond by gamma irradiation. Hydroxyapatite modified by atelocollagen had been characterized by several surface sensitive techniques, such as FT-IR, SEM, XPS. The investigations showed that the collagen, a bioactive macromolecule, was immobilized on the HA surface through covalent bond.
Authors: Xiao Min Wang, Xu Dong Li, Gui Qiu Zheng, Xiao Liang Wang, Xing Dong Zhang, Zhong Wei Gu
Abstract: Poly(vinyl alcohol) (PVA) was introduced during in situ synthesis of hydroxyapatite (HA) in neutral collagen (COL) solution and final PVA-COL-HA nanohybrids were achieved via sequential steps including gelation by fibrillogenesis, freezing-thawing physical crosslinking, removal of unreacted residues and dehydration. This method is expected to endow the pure PVA with good bioactivity and meanwhile the presence of elastic PVA would improve the properties of COL-HA composites. The phase, microstructure and possible molecular interactions of the achieved PVA-COL-HA nanohybrids were analyzed by using X-ray diffraction, Fourier transform infra-red spectroscopy and scanning electron microscopy. The results indicate that the inorganic phase is poorly crystallized apatite with a nanometer size due to the confinement of organic macromolecules which forms a network structure.
Authors: Qing Rong Wei, Xiu Dong Yang, Jian Lu, Bo Zhang, Bo Jiang, Hong Song Fan, Ji Yong Chen, Zhong Wei Gu, Xing Dong Zhang
Abstract: As a natural biomaterial, collagen especially pepsin-solubilized collagen (type I) has been used widely in biomedical fields due to its excellent biocompatibility. In this preliminary study, we investigate the effect of some inorganic ions which are frequently utilized in the preparation of collagen on the morphology and crystallinity of fibrils. The scanning electron microscope and x-ray diffraction were applied to analyze the morphology and the crystallization of the reconstituted collagen fibrils, respectively. Although further studies are needed, these initial results indicate that by controlling the self-assembly conditions of collagen molecules, we may achieve the desired properties of fibrillar collagen products.
Authors: Yi Wang, Hong Song Fan, Xian Tao Wen, Yu Mei Xiao, Zhong Wei Gu, Xing Dong Zhang
Abstract: Hydroxyapatite/polymer scaffolds with proper biomechanical properties and stable 3-D porous structure were fabricated by combining gas foaming with solvent-casting/particle-leaching technique, in which novel solid H2O2 were used as a porogen. During the manufacturing process, we found that the porosity, compressive strength and microstructure of the composites are varied from each other while different solvents (dichloromethane, acetone, chloroform and 1,4-dioxane) were used. Porosities of the specimens increase from 72±5 to 87±5% in accordance with the increase of boiling point from 39.75 to 101.32 °C, while compressive strength decreased (4.8±0.7- 0.5±0.3 MPa). Interactions of HA/solvent and PLA/solvent together with evaporation dynamic tests of different solvents were investigated. The results show that the evaporation rate of the solvents is the most important factor affecting the final properties of the scaffolds.
Authors: Xiao Liang Wang, Xu Dong Li, Xiao Min Wang, Jian Lu, Hui Chuan Zhao, Xing Dong Zhang, Zhong Wei Gu
Abstract: Collagen (Col) and chitosan (Chi) are both natural polymers and have received extensive investigation in recent years in the field of tissue engineering, but there are few reports on the introduction of hydroxyapatite (HA) into the Col-Ch system. In this study, based on the miscibility of these two polymers under proper condition, hydroxyapatite (HA) was synthesis in the Col-Chi system by in-situ co-precipitate method to give rise to a novel nanocomposite. The structural characterization of such Col-Ch-HA nano-materials was carried out by using FT-IR, XRD, SEM and TGA analyses with main components and Col-Chi samples used for comparison. It was found that there exist interactions between Col and Chi molecules. The nucleation and growth of inorganic phase occurs in the Col-Chi system and final products are uniform dispersion of nano-sized HA in the Col-Chi network without obvious phase separation. This novel nanocomposite would be a promising material for bone tissue engineering.
Authors: Qing Rong Wei, Jian Lu, Hui Chuan Zhao, Bo Jiang, Bo Zhang, Zhong Wei Gu, Xing Dong Zhang, Ji Yong Chen
Abstract: In order to develop a bone-filling material with osteoinductive potential, a composite micorspheres of collagen molecules and biphasic calcium phosphate (BCP) was prepared by utilizing emulsion polymerization and the intrinsic self-assembly of collagen. The prepared microspheres were analyzed by granularity test, scanning electron microscopy (SEM), infrared spectra (IR) and enzymatic digestion experiment. The results showed that the collagen matrix of fibrils was reconstituted in the droplets, and the native triple-helix structure of collagen was still maintained. The study provides an effective way to prepare microspheres of collagen and BCP composite.
Authors: Yu Jiang Fan, Jie Liang, Guo Ping Chen, Tetsuya Tateishi, Zhong Wei Gu, Xing Dong Zhang
Abstract: Linear and Star-shaped PCL-b-PEG copolymers were synthesized through a two step process, including the first step to synthesize the star-shaped PCL through ring-opening polymerization of Γ-caprolactone initiated from multi-functional alcohol under the existence of tin(II) ethylhexanoate [Sn(Oct)2] catalyst, and the following step to couple the obtained star-shaped PCL with PEG segments using bi-functional linker. The structure of the polymers was confirmed by IR, NMR, GPC, et al. The aggregation behaviors of the star-shape copolymers were compared with that of the linear block copolymer with corresponding molecular weight of each arm, and the influences of structure factors were discussed.
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