Preparation And Properties Of Barium Titanate/calcium Silicate Biopiezoelectric Composites

Bone is the hardest tissue and organ of the human body,which maintains the normal movement of the body and is the guarantee of people's healthy life.However,in daily life,various bone tissue defects will inevitably occur.How to treat bone tissue defects and related infections has always been a major problem in the medical field.Piezoelectric signals exist in natural bones,and they can significantly promote bone repair.Therefore,materials with piezoelectric properties are widely used in the study of bone repair.Among them,barium titanate is a kind of piezoelectric material with good biocompatibility.It not only has certain bone repair potential,but also has antibacterial effect through piezoelectric catalysis.However,the repair of bone defect is a very complex process.It is not enough to promote osteogenesis only by piezoelectric properties.It also requires materials to have good bioactivity,while traditional piezoelectric materials,including barium titanate,often do not have bioactivity.Calcium silicate bioactive material is a kind of material with high bioactivity and good biocompatibility.It can induce inorganic calcium and phosphorus ions in the system to deposit on the surface of the material under physiological environment,forming hydroxyapatite,the main inorganic component of bone tissue.In addition,it has good degradability and can slowly release active silicon ions with the functions of regulating tissue and vascular regeneration.Therefore,it has attracted more and more attention in the field of bone repair.But calcium silicate itself is not piezoelectric.Therefore,in this paper,barium titanate with piezoelectric property and calcium silicate with biological activity are combined in order to obtain bone repair materials with better performance.Firstly,barium titanate / calcium silicate composite ceramics with piezoelectric and bioactivity were prepared by solid-state sintering.The basic properties of the materials were characterized,and the mineralization and biocompatibility in vitro were evaluated;Then,barium titanate / calcium silicate composite powder with excellent antibacterial properties was synthesized by hydrothermal method and coprecipitation method.The main research contents and results of this paper are as follows:(1)The preparation of barium titanate / calcium silicate biological piezoelectric composite ceramics and its properties of inducing mineralization and osteogenesis were investigated.In this study,calcium silicate was compounded into barium titanate.Different composite ceramics were obtained by solid-state sintering by adjusting sintering temperature and composition ratio.The results show that the introduction of calcium silicate significantly reduces the piezoelectric properties of the materials.When the content of calcium silicate is 30%(bt0.7cs),the piezoelectric constant of the composite ceramics decreases from 169 PC · n-1 to 4 PC · n-1,but it still has good biological activity of inducing mineralization.When the content of calcium silicate is less than 30%,the composite ceramics will be difficult to re induce mineralization.When the content of calcium silicate reaches 40%,its piezoelectric property almost disappears.Cell experiments in vitro confirmed the good biocompatibility of the material.(2)The preparation of barium titanate / calcium silicate composite powder and its catalytic and antibacterial properties were studied.Firstly,barium titanate nanoparticles were synthesized by hydrothermal method.Then,barium titanate / calcium silicate composite powder was further synthesized by coprecipitation method.Under ultrasonic vibration,barium titanate showed good catalytic performance.At 40 min,the degradation rate of RH B reached 98%,and its antibacterial rates against Staphylococcus aureus and Escherichia coli were 50.8% and 51.5% respectively.With the introduction of CS,although its catalytic performance decreased when BT: CS =1:1,the dissolution of CS increased the p H in the system and reduced the viability of bacteria.On the contrary,the antibacterial rate of the composite against Staphylococcus aureus increased to more than 95.3%,and the antibacterial rate against Escherichia coli reached 99.6%.