| Hydroxyapatite(Ca10(PO4)6(OH)2,HA)is the main inorganic component of human bone tissue which has been widely used in respect of hard tissue replacement and filling due to its good biocompatibility and bone conduction ability.In bone mineral,HA mainly exists in the form of nanometer size,which has better biocompatibility than conventional HA.The phase composition with piezoelectric properties can be used to bone grafts which is advantageous to the induction of bone growth.Accordingly,the BaTiO3(BT)ceramics can be used as a piezoelectric active component due to its excellent biocompatibility and piezoelectric property.Therefore,BT/HA nanocomposite has become one of the research hot spots for the bone substitute materials.At present,the composition of HA and BT is mainly concentrated in the powder mechanical pressing or coating forming.However,only two phase component of composites are obtained via these two methods which are just mixture or coating.Research shows that the performance of nanomaterials was mainly depend on the structural characteristics,such as morphology,size and structural stability.So far,few reports have been made on the the effect of BT/HA nanocomposite structure characteristics on the electrical,mechanical and biological performance.Based on this,the BT/HA composite structure units of different tissue structures were successfully synthesized in this paper:plate-like,rod-like and spherical structures of BT/HA nanocomposite materials.Firstly,the characterization of different morphology were completed.Then,the electrical,mechanical and biological properties of sintering ceramic block with different morphology have been measured.Meanwhile,the formation process of rod-like composite was revealed by the First-Principles calculation.In addition,the formation mechanism of different structures was also discussed.The major research contents and achievements are as follows:(1)The composite materials were 35 nm HA and Ca3(PO4)2 nanoparticles grown on BT plate prepared by hydrothermal reaction of precusor of HA and BT.The barium salt(BaCl2),titanium salt(tetrabutyl titanate(C16H36O4Ti))salt,calcium salt(CaCl2)and phosphorus((NH4)2HPO4)were used as raw materials in this topic.The influence of BT and HA precursor ratio,reaction temperature and time on the product were studied systematically.The results showed that Ca3(PO4)2 is always obtained in the product which indicated that it's very difficult to obtain the single BT/HA nanocomposites.(2)The composite materials were 30 nm HA nanoparticles and BT with length of about 150 nm,diameter of 10?30 nm,which were prepared by dispersing HA nanoparticles in anhydrous ethanol and hydrothermal reacted with BT precursor solution at 160 ? for 12 h.The influence of solvent on the reaction product morphology and size were studied.According to the First-Principles calculation results:alcohol water weak weak coordination compound can be formed in the solvent molecular,which was adsorbed around the BT and forced BT crystal growth along the C axis,thus leading to the rod like structure.Finally,the BT nanorods/HA nanoparticles composites were obtained.The testing results of the morphology and property of the ceramic block obtained from different solvent system(ET/H2O,H2O,DMF(dimethylformamide)/H2O and EG(ethylene glycol)/H2O)showed that the piezoelectric coefficient(d33 value of 6.88 pC/N),compressive strength(69.30 MPa)and cell proliferation rate(125.4%)of ET/H2O system ceramic blocks were higher than other systems.(3)The nanocomposite was successfully hydrothermal synthesized at 160 ? for 12 h,which was BT microsphere with average diameter of 0.15 ?m covered by HA nanoparticle with average diameter of 30 nm.The characteration and analysis results showed that the surface of BT microsphere was covered by HA nanoparticles,in addition,this morphology was retained in ceramic blocks after sintering.The piezoelectric coefficient d33 of the ceramic block is about 0.1 pC/N,revealing that the bioactive component HA nanoparticles can shield the electroactive component BT microsphere,leading to a significant decrease in piezoelectric properties of the materials.While the compressive strength(mean 30 MPa)and the cell proliferation rate(127.1%)were relatively stable with the change of the composition.(4)The HA nanorods were successfully prepared by controlling the reaction temperature of the precursor solution by hydrothermal reaction at 120? for 12 h.Then,the nanocomposite materials were BT nanoparticle with average diameter of 20 nm grown on the HA nanorods with average diameter of about 80 nm and length of 0.5 ?m,obtained at 160 ? for 12 h by scattering HA nanorods in BT precursor solution.The piezoelectric properties,tensile strength and cell proliferation rate of sintered ceramic block were studied,which were about 1.54 pC/N,12.58MPa,130%respectively.The molecular structure of HA crystal structure,surfactant CTAB,BT crystal structure and metal ion chelating agent C6HsO7 was calculated by First-Principles calculation.The results showed that the CTAB passivated(100)crystal surface of HA,which made it grown along the axis of[001],and the HA nanorods can be obtained by crystal anisotropy growth.The C6H8O7 molecules are adsorbed on the adjacent O atoms on the surface of the BT crystal,allowing the crystal to isotropy growth and obtain nanoparticles. |
PDF Full Text Request