Preparation And Characteristic Of Hydroxyapatite/Gelatin Composite

The study aims at the poorer mechanical property hydroxyapatite(HA) biomaterials although they possess the excellent biocompatibility. It is difficult to be used as bone replacement at the loading site in clinic. In the present study, the mechanical property of hydroxyapatite has been improved by adding plastic phase gelatin.Hydroxyapatite/Gelatin was synthesized by adding gelatin solution into the reactive solution when HA was formed. The homogenous composite was obtained due to two phases were co-precipitated in reactive solution. The optimal technical parameter to prepare HA/gelatin composite, crosslink of gelatin and formed and dried were obtained. The results suggested that pH played an importuned role during synthesis of HA/gelatin composite. It is benefit to co-precipitation of HA and gelatin when the pH value of reactive was about equipotential point of gelatin. In the present study, pH=9 was chosen. The lowest concentration of crosslinkage, glutaraldehyde (GA), and the lowest concentration of gelatin in the slurry of HA/gelatin were all 5% (wt%). The volume proportion of GA and the slurry of HA/gelatin was 15:100. The composite do not craze and distort in the drying process using homemade moulding equipment.The phase components were analyzed by X-Ray Diffraction (XRD). The microstructure of composite was observed by Scanning Electronic Microscopic (SEM). The chemical bonding between hydroxyapatite and gelatin were analyzed by Fourier-transformed infrared spectrophotometry FT-IR and Differential Thermal Analysis (DTA). The content of gelatin in the composite was calculated from TG data. The mechanical properties ofcomposites were tested using Instron Material Testing Machine. The in vitro biodegradation of composites were investigated in stimulated body fluid (SBF). It has found that a layer of apatite was formed on the composite surface when they were immersed in SBF.The XRD results demonstrated that the inorganic phase of hydroxyapatite/gelatin composites was HA in the present experiment. HA crystal grains sizes become smaller due to adding gelatin. Its sizes was more thinner, the more gelatin was added. The chemical bonding between HA and gelatin gave rise to the HA crystal lattice aberrance, which were determined by the increase of diffraction angle of various. SEM observation showed that there were some thin cracks on the fracture section of composites. It maybe gelatin fibrous prohibited the composite shrinkage. The FT-IR results of red-shift of 1339cm"1 confirmed the chemical bonding between HA and gelatin. TG results showed that the content of polymer of HA/gelatin-9+GA was more than that of HA/gelatin-9 and HA-9. It indicated that the gelatin content in composite increased with the adding of GA to promote the net-like gelatin formation. The gelatin content of HA/gelatin-9+GA was 32% (the experiment design is 33.3%). The exothermic peak of HA/gelatin-9+GA composite moved to 500°C to 600°C, which was higher to precipitate that of HA/gelatin-9. It confirmed that there were more stable structure in HA/gelatin composite when GA was added. The mechanical measurement showed that the compressive strength of HA/gelatin-9 was the highest among the three specimens. But HA and HA/gelatin-9 behaved the brittle fracture. HA/gelatin-9 +GA behaved the plastic fracture although their compressive strength decreased. In vitro experiment showed that HA/gelatin-9 and HA-9 were...