Papers by Author: Jian Lu

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.

Abstract: The mRNA expression of Cbfa1 and osteocalcin gene induced by calcium phosphate ceramics (Ca/P) were quantitative analyzed according to real-time RT-PCR method in this work. C2C12 cells were co-culture with four kinds of porous Ca/P ceramics for 2 and 5d without adding other growth factors. The four kinds of Ca/P ceramics were pure hydroxyapatite (HA) sintered at 1250°C and HA/TCP with a ratio of 60/40 sintered at 1100°C (HT1), 1200°C (HT2) and 1250°C (HT3) respectively. Real-time RT-PCR analysis found the Ca/P ceramics induced positive expression of Cbfa1 and osteocalcin in C2C12 cells, After 5 days culture, Cbfa1 and osteocalcin showed obvious higher expression compared with that in 2 days. Cbfa1 and osteocalcin expression in BCP was much higher than HA, and the expression level of osteocalcin was HT1>HT2>HT3>HA. Our results showed that Ca/P ceramics alone were sufficient to induce C2C12 cells to osteoblastic differentiation and the sinter temperature and phase composition of Ca/P ceramics could affect their osteoindctive capacity significantly.

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.

Abstract: Biomimetic coating on roughed titanium plates were prepared in this work by a cathode deposition method in calcium phosphate solution electrolyte. The coatings of plate-like apatite crystals were deposited on the titanium plates under a constant potential of 2.0V for 60 min at 37. The coating crystals were identified to be carbonate-containing apatite (bone-like apatite) by X-ray diffraction and scanning electronic microscopy. The cell proliferation and adhesion of L929 cells on the titanium metal plates with biomimetic coating and the titanium plates with roughed-only were tested. The results showed that biomimetic coating on titanium surface can enhance the materials bioactivity. The study indicated that cathode method is potential to prepare biomimetic coating on titanium implants with excellent bioactivity.

Abstract: In this study, bovine serum albumin protein (BSA) was introduced to investigate the co-precipitation process of calcium phosphate and BSA on bioactivated Ti. Commercially pure titanium were bioactivated firstly, and then immersed in a highly supersaturated stable calcium phosphate (Ca-P) solution at three different conditions. The samples designated as Ti-C, Ti-C-CB, and Ti-C-B for control. The samples were evaluated by SEM with EDX, XRD and XPS. The co-precipitation of BSA protein and Ca-P influenced the morphology of the crystals of Ti-C-CB significantly. In terms of the immersion in the Ca-P solution containing BSA, the co-precipitation of Ca-P with BSA on the surface of Ti-C-CB was a chemical process rather than simple physical adsorption, which was most possibly achieved by the linkage of –COO− groups to Ca-P. Such coprecipitated interaction led to the formation of a tight, dense and uniform Ca-P coating.

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.

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.

Abstract: A kind of medical collagen was prepared by hydrogel formation method. Chemical and physical properties were investigated by FTIR, amino acid analysis, SDS-PAGE, carbohydrate content analysis, heavy metal content analysis. Degradation experiments in vivo and subsequent histological investigations were carried out to evaluate the biological performance. The results suggested that the collagen achieved is promising in tissue engineering scaffold materials for a long-term (more than 12 weeks) implantation application.

Abstract: Hydroxyapatite/collagen (HA/COL) composites were prepared using coprecipitation and in-situ synthesis methods. All these processes yielded nanosize poorly crystallized hydroxyapatite/collagen composites. The low temperature in situ formed composites showed some features of natural bone in phase composition, crystal size and crystallinity. Compare with the composite prepared by coprecipitation synthesis, the composite resulted from a low temperature in situ synthesis method showed better homogeneity and mechanical properties. It is confirmed that the low temperature in situ synthesis method was an effective way to obtain biomimetic nanoHA/COL composites with good homogeneity and mechanical properties.