Preparation And Characterization Of Ag/Cu/HAP And Its Composites

Hydroxyapatite(HAP) is the main inorganic component of the natural bone and tooth.The Ca2+ in HAP can complex with organic substance that contains carboxyl group such as amino acid,protein, organic acid,so HAP has excellent biocompatibility and bioactivity. HAP is considered to be the fantastic substitute material in bone'repair because it can firmly combine with bone tissue and accelerate the growth of bone.But the bending strength and compressive strength of pure HAP material are very low, which largely limit the application of HAP material as the substitute for human body skeleton.Therefore,a composite of HAP and other materials should be prepared to improve the brittleness and osteo-inductivity of HAP.The surface of HAP implant is often infected for the looseness and vibration of the implants,which would not only shorten the life of implant, but also cause pain and economic burden to patients because of the second surgery. Now drug-embedded bone implant and antibiotic recombinant bone are frequently used to avoid infection,but these methods also have their disadvantages such as cannot be sterilized by heating, complexity of process and lack of long-term curative effect. The goal of this study is to synthesize nanosized HAP composites carrying metallic ion whose comprehensive performance of bone-repair materials is improved.The metal containing HAP composites not only have excellent bioactivity and biocompatibility, but also have anti-bacterial function and fantastic mechanical property.In this paper, the HAP carrying Ag+and Cu2+(Ag/Cu/HAP)was prepared by using the co-precipitation method. Factors affecting the preparation of Ag/Cu/HAP were studied, besides,the effects of doped Ag+ and Cu2+ on the microstructure and properties of HAP crystals were also discussed.In addition, a silk-fibroin/Ag/Cu/HAP composite(SF/Ag/Cu/HAP) with excellent anti-bacterial function and mechanical property was prepared. The factors affecting the preparation of silk-fibroin/Ag/Cu/HAP composite was also investigated. The mechanical property of the SF/Ag/Cu/HAP was tested and the anti-bacterial property and biocompatibility of the SF/Ag/Cu/HAP were confirmed through freely fallen bacteria method and animal cell culture experiments.The composition and microstructure of the HAP composite powders were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR).The results were as follows:Ag/Cu/HAP can be synthesized by using the co-precipitation method.The crystal of Ag/Cu/HAP takes platelet shape different from the needle shape of pure HAP because of the effects of doped Ag+ and Cu2+. The crystal size of Ag/Cu/HAP was smaller than that of pure HAP. The temperature, pH, concentration of reaction solution and starting material-feeding sequence could greatly affect the morphology, crystallinity and size of the Ag/Cu/HAP composite.High temperature calcination changes the crystal shape of Ag/Cu/HAP from platelet to globular.The silk fiber can be easily resolved in solution that contains CaCl2, C2H5OH, H2O with the molar ratio of 1:2:8.The silk-fibroin/Ag/Cu/HAP composite was synthesized by using the co-precipitation with one step when the mixture solution of silk fibroin and the starting materials of Ag/Cu/HAP was used as the reaction solution. The crystal size and shape of silk-fibroin/Ag/Cu/HAP composite was greatly affected by reaction temperature. The ratio of HAP to SF in SF/Ag/Cu/HAP composite influences the cross-linking degree of HAP in crystal.The more SF in the crystal,the higher degree of cross-linking of HAP in crystal.Both the Ag/Cu/HAP composite and SF/Ag/Cu/HAP composite have effective anti-bacterial property. Moreover, SF/Ag/Cu/HAP composite has quite good compressive strength and fantastic biocompatibility.