Hong Song Fan

Evaluation of Bioactivity and Cytocompatibility of Nano-Hydroxyapatite/Collagen Composite In Vitro

A nano-hydroxyapatie/collagen composite was fabricated by an in situ synthesis technique. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) analyses for the composite indicated crystals on the collagen fibril matrix exhibited certain orientation. Bioactivity of the composite was investigated through in vitro tests in a sterile simulated body fluid (SBF) system. Scanning electron microscopy and energy-dispersive X-ray analysis of the composite showed that the composite had the ability to induce the formation of calcium phosphate crystals on the surface of the composite in SBF. The cytocompatibility of the composite was evaluated by in vitro cytotoxicity test. Both the results from MTT assay and scanning electron microscope (SEM) observations indicated that the composite had no adverse impact on cell proliferation and morphology. The results imply the composite is high bioactive and has good cytocompatibility.

Preparation of Electrospun PLA Nanofiber Scaffold and the Evaluation In Vitro

A electrospinning process to prepare soft tissue engineering scaffold was introduced in this study. This kind of scaffold was composed with ultrathin fiber and characterized with high porosity, well-interconnected pores and high surface-to-volume ratio. Biodegradable polylaticacid (PLA) was used to spin the scaffold and the scaffold was evaluated in vitro by analysis the microscopic structure, porosity, mechanical property, especially cytocompatibility. The results indicated that the electrospun PLA scaffold showed good cytocompatibility and the tensile property of electrospun scaffold was similar to human’s soft tissue. It could be expected that the electrospun scaffold would be potential in soft tissue engineering or soft tissue repair.

Compare of Electrospinning PLA and PLA/β-TCP Scaffold in Vitro

In recent years, electrospinning process is gradually applied in producing tissue-engineering scaffold. In this study, we chose polylacticacid(PLA) and β-tertiary calcium phosphate(β-TCP) as raw materials to fabricate PLA/β-TCP biodegradable composite scaffold by electrospinning process. The characteristics of the scaffold and effect of the scaffolds to cell proliferation and cell adhesion was studied. Compare with pure PLA scaffold, blendingβ-TCP in the spinning process of the scaffold could improve the properties of the scaffold, especially the hydrophilicity and the proliferation and adhesion of cells, this means that the material is more potential to be used as tissue engineering scaffolds.

Preparation and Characterization of Nano Hydroxyapatite

The aim of this study is to prepare nano hydroxyapatite powder. Hydroxyapatite powder was prepared via co-precipitated method with the addition of citric acid at pH 9-11 in ambient environment. The precipitates were aged for 24hs, and then milled into powder after washed and dried. The particle morphology and particle size of as prepared HA powders were characterized. The results showed that hydroxyapatite powder with width of 10-30nm and length of 30-100nm was prepared by wet co-precipitation.

Fabrication of Porous Hydroxyapatite Ceramics by Microwave Sintering Method

Microwave processing of porous hydroxyapatite ceramics was investigated in a dual frequency microwave-sintering furnace. The results revealed that microwave-sintering process could get sintered ceramics at much shorter sintering time and at lower sintering temperature than that of the conventionally heat-sintering process. Further, the microwave-sintered samples showed much smaller grain size and more uniform microstructure and reached a comparable compressive strength. The mechanism of rapid heating behavior of hydroxyapatite ceramics in microwave was also discussed. The results revealed that microwave processing was a promising method for sintering porous hydroxyapatite ceramics.

Experimental Study on Construction of Vascularized Bone Graft with Osteoinductive Calcium Phosphate Ceramics In Vivo

This study was to aimed to explore a new method for fabricating a bone substitute, which is constructed of vascularized bone graft with osteoinductive calcium phosphat e cer mics in vivo. A total of 32 small and 16 big ceramic cylinders were prepared, and bone-like apatite l yer was formed on the surface and the pore walls of ceramics in revised simulate d body fluid (RSBF). The smaller ceramics cylinders were implanted in dorsal muscles of dogs to evaluate the osteoinductive capacity. The bigger cylinders were mixed with fresh bone tissue and were implanted near a branch of femoral blood vessel in the dog’s leg muscles to construct vascularized bone gr afts. After implantation for 6 and 12 weeks, the specimens were harvested. The specimens were evalua t d by blood vessel staining, histological observation, tetracycline fluorescence labeling, Tc–MDP SPECT and mechanical tests. The results showed that bone formation was found in all the samples a nd bone grafts had good blood supply. This result indicated that this kind of calcium phosphate cera mi s had a good osteoinductivity and that vascularized bone grafts could be constructed wi th osteoinductive calcium phosphate ceramics in vivo. Introduction Bone defect is a common disease in clinic and to date, there is no s atisfactory method to treat the segmental bone defect. At present, autograft, allograft, xenograft and alloplasm materials could be used for repairing bone defects. Autograft is the best bone substitute, but it causes a secondary wound. Allograft and xenograft may bring immune response and infectious dise ase. Alloplasm material have been developed as a major bone substitute [1]. An ideal bone substitute should possess good biological and mechanical properties. The biological properties of an i deal bone substitute include biocompatibility, osteoconductivity, osteoinductivity, osteogenesis capabilit y. In 1980s, the appearance of tissue engineering brought about opportunities for repairing bone defects. Great achievements have been obtained in this field in the last 20 years [2] . But there are still some challenges ahead for bone tissue engineering [3]. Until now, no tissue e ngine ring bone composed of scaffold and cultured cells in vitro has been permitted to be applied in clinic [4]. Calcium phosphates ceramics are frequently used as bone substitute m a erials because of their similarity to the mineral phase of bone, absence of antigenicity, a nd excellent osteoconductivity. Some studies have proved that calcium phosphate ceramics with special str u ture could induce bone formation in soft tissue [5]. Based on the exploration of the osteoinducti ve mechanism, Zhang [6] proposed a new concept of bone tissue engineering in vivo, i.e., bone grafts could be constructed directly with osteoinductive biomaterials singly or osteoinductive biom aterials mixed with fresh bone tissue in some areas of the body. This study was conducted to explore a new method for fabricating bone substitute, which constructed vascularized bone graft with osteoinductive c alcium phosphate in vivo. Materials and Methods Preparation of the ceramics Calcium phosphate ceramics was prepared by H 2O2 foaming method and sintered at 1250oC for 3 hours with wet-synthetic calcium phosphate powde r. The chemistry of Key Engineering Materials Online: 2003-12-15 ISSN: 1662-9795, Vols. 254-256, pp 801-804 doi:10.4028/www.scientific.net/KEM.254-256.801

Characterization of an Insoluble Collagen Sponge and the Potential for Tissue Engineering Scaffold

Collagen has been widely used in biomedical field, such as scaffolds for tissue engineering. However, the rapidly biodegradation and weak mechanical strength of collagen limited its application. In this study, an insoluble collagen extracted from cattle hide was designed as scaffold to act as a three-dimensional substrate for tissue engineering. The received insoluble collagen sponge was analyzed by scanning electron microscopy, infrared spectroscopy, mechanical testing and thermogravimetric-differential thermal analysis. In addition, the degradation was performed in vitro using collagenase. The results showed that the insoluble collagen had the same triple helical domain as acid-soluble collagen, while the compression strength was greatly improved and the degradation rate was reduced. The insoluble collagen sponge with good stability should be promising in tissue engineering scaffold applications.

Rat Bone Marrow Cell Responses on the Surface of Hydroxyapatite with Different Topography

It is well known that the cellular responses are related with both physical and chemical characteristics of substrate, including surface topography. In the present study，the effect of surface topography of hydroxyapatite (HA) on rat bone marrow cell (rBMCs) response was investigated. HA disc-shaped pellets with various topography were manufactured by single-axis pressing methods. The rBMCs responses on materials including cell morphology and proliferation were evaluated by SEM and MTT methods respectively, and the differentiation potential was assessed by total protein content and alkaline phosphatase (ALP) activity testing. The results showed that the cell porliferation was higher on HA surfaces with macropore structure, while ALP activity was lower. No significant difference in the cellular responses on the pore distribution and orietation was observed. However, the pore structure had a potential to guide cell orientation by gathering the cells inside the pores rather than on the ridges. Since ALP served as an indicator of early osteoblast differentiation, in this study its higher expression on HA surface with micropores suggested that surface microtopograhy exhibited an important effect on early osteoblast differentiation process.

Bovine Serum Albumin Adsorption on Hydroxyapatite and Biphasic Calcium Phosphate and the Correlation with Zeta Potentials and Wettability

Studying on the interaction between proteins and calcium phosphate implants is one of the basic subjects in biomaterials science and engineering. In this work, zeta potentials and contact angles of hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramics were measured, and the adsorption behaviors of bovine serum albumin (BSA) on the surfaces were investigated. The adsorption isotherms of BSA on both ceramics follow the Langmuir type, however, BCP shows higher BSA adsorption ability. The differences of contact angles and zeta potentials in HA and BCP are the key factors to determine their ability to bind BSA molecules.

Fabrication of Porous Titanium with Biomechanical Compatibility

Porous titanium with good strength and three-dimension pore structure was fabricated by using H2O2 as vesicant foaming titanium powder. The compressive strength, bending strength and Young’s modulus of porous titanium with the porosity of 58vol% are 190.7Mpa, 159Mpa and 4.15Gpa, respectively, similar to that of the nature bone. This kind of porous titanium with good bio-mechanical compatibility may be potential to alleviate the problems caused by the mismatch of the strength and Youngs modulus between implant (110 GPa for Ti) and bone. Moreover, the pores (mainly in 100-700µm) are all interconnected and there are many microspores (about 10µm) in the wall of the macrospores. This porous structure would endow the materials with better activity.