| Bioactive ceramics have been used for bone defect filling,fracture repair and replacement of diseased tissues in bone tissue engineering because of their good biocompatibility and biological activity.Hydroxyapatite whiskers are widely used as bioceramics because of their similar inorganic composition to human bone,have good bone conductivity,biocompatibility and fracture toughness.Gelatin is the product of collagen which is the main structural protein of human skeleton,Silica is one of the main trace elements in human body.They are also often used to repair human bone defects.In this article,hydroxyapatite whisker material was successfully prepared by hydrothermal method.Silicon modified hydroxyapatite whisker material was obtained by Stber method with tetraethyl orthosilicate solution.Different porous scaffolds were prepared by the method of organic foam impregnation and light curing.The components of the scaffolds were analyzed by means of XRD,FT-IR and so on.The microstructure of the scaffolds was observed by scanning electron microscope,and the properties of the scaffolds were also studied.The results are shown as follows.(1)Hydroxyapatite whiskers and silicon modified hydroxyapatite whiskers were successfully prepared.The dispersibility of the whiskers was good,and the length of the whiskers was mainly between 60 and 160 um.The length of the whiskers could reach more than 230 um,and the aspect ratio was mainly between 14.68 and 65.72.Silicon modified hydroxyapatite whiskers are coated with spherical silica particles with diameters ranging from 500 to 600 nm.With the increase of tetraethyl orthosilicate,the number of particles increases.The whiskers are connected with the whiskers in the form of covalent bonds.The surface of the whiskers is rough,forming a screw steel effect and enhancing the mechanical strength of the hydroxyapatite whiskers.Cytotoxicity test showed that the prepared hydroxyapatite whiskers and silicon modified whiskers had no cytotoxicity.(2)The preparation process of silicon modified hydroxyapatite whisker scaffolds by foam impregnation method was designed by orthogonal test,and the optimal preparation scheme of the scaffold was obtained.The best comprehensive performance plan is: polyurethane foam carrier structure is 16 hole 0.5mm carrier,the amount of ethyl orthosilicate is 30 ml,the gelatin concentration of the scaffold is 6wt%,the porosity of the scaffold sample reaches 88.08%,the compressive strength is 1.7235 MPa.Bone-like apatite deposits occurred during the degradation of the scaffolds,and the addition of silica improved the bioactivity of the scaffolds.The scaffolds degraded rapidly and collapsed in different degrees within 20-50 days.The cytotoxicity grade of the scaffolds was 0 or 1,and the scaffolds had no cytotoxicity.(3)Hydroxyapatite whisker scaffolds and silicon modified hydroxyapatite whisker scaffolds were successfully prepared by light curing technology.The micro-pore structure left by resin sintering is found in the scaffolds.The pore size is mainly 20-50 um,and there is delamination phenomenon.The porosity of the scaffolds measured by drainage method is over 65%,the highest is 83.29%.The mechanical strength of the whisker bracket with the effect of threaded steel doubled with the addition of silica.After gelatin impregnation and glutaraldehyde crosslinking,the mechanical strength increased 20-40 times,and the maximum average compressive strength reached 4.32 MPa.After 7 weeks of degradation,the degradation rates of the four scaffolds were 42.63%,69.54%,78.15% and 69.43%,respectively.The cytotoxicity results showed that the four scaffolds had no cytotoxicity.The performance of the scaffolds prepared by the experiment meets the requirements of bone tissue engineering. |
PDF Full Text Request