Effect Of BSA On Growth Behavior Of Mineralized Layer On Si Doping Hydroxyapatite Prepared By Precipitation Method

In recent years,it have been found that Si doping could decrease the crystalline,improve the degradation and change surface chemical properties of HA ceramics.Which have effects on mineralization performance of HA ceramics in vitro and in vivo.Currently,the common method to study the ceramics' in vitro mineralization performance is to characterize the thickness and composition of mineralized layer growth on ceramics in stimulate body fluid(SBF),however,it cannot study the mineralization process in real-time and has its limitation.Proteins have great effects on the formation of bone-like apatite.In hence,this paper studied mineralization process of Si-HA ceramics in SBF by QCM-D technology,and investigated the effect of BSA preadsorption on the growth rate and morphology of mineralized layer.Nano needle-like Si-HA as-powders,with varying amounts of silicon,were successfully prepared using an aqueous precipitation method.Si doping decreased the crystalline of HA as-powders: Si doping amorphous calcium phosphate(Si-ACP)and amorphous silica(SiO2)was detected when Si dopant content exceeded 1.5 wt%.After heat treating at 1000 oC,the precursors transformed to biphasic Si doping ?-Tricalcium phosphate/HA(Si-?-TCP/HA)particles and Si-?-TCP became the main phase when Si dopant content exceeded 4.0 wt%.The effect of synthesis temperature on thermostability of as-powders was also studied.The higher temperature the as-powders synthesized,the better thermostability they had.The ideal condition to obtain pure Si-HA ceramics was as follows: synthesis temperature was 80 oC and sintering temperature was 1000 oC.The effect of Si dopant content on sintered compactness and mineralization performance of Si-HA ceramic was studied.The results showed that Si doping reduced the density and improved mineralization activity of HA ceramics.The effect of BSA on the morphology of mineralized layer in static SBF solution was studied.The results showed that flake-shape mineralized layer formed in r-SBF solution without BSA while sphere-shape mineralized layer formed with BSA.The cell viability of mBMSCs on mineralized layer with different morphology was in the order of flake-shape layer>sphere-shape layer>bare layer.The real-time dynamic adsorption process of BSA on Au,HA and Si-HA coating,fabricated by an electrophoretic deposition(EPD)method,was investigated by QCM-D technology.The results showed that the adsorption capacity of BSA on different substrate surface was in the order of Au?HA>Si-HA(abbreviated as BSA-Au,BSA-HA and BSA-Si-HA).Si doping inhabited BSA adsorption.The effect of BSA preadsorption on the mineralization process of Si-HA in SBF solution was studied by QCM-D technology.The results showed that BSA preadsorption affected the growth rate and morphology of mineralized layer.The growth rate on the surface of BSA adsorption layer was smaller than bare surface.Meantime,more number and more uniform distribution of particles were obtained on BSA adsorption layer than bare surface.In summary,BSA preadsorption promoted the nucleation and inhibited the growth of mineralized layer.This finding indicated BSA could modulate the size of mineralized layer,which exhibited significant benefits for fabricating uniform-and small-sized calcium phosphates coating.