Synthesis,Characterization And Related Properties Research Of Trace Element-Doped(or Photocatalytic) Hydroxyapatite Composites

Hydroxyapatite(HA,Ca₁₀?PO₄?6?OH?₂)is a new kind of multifunctional biological material with good performance,such as biocompatibility,biological activity,adsorption,ion exchange and rare non-toxic,so it has always been a hot topic in recent years.However natural hydroxyapatite has insufficient performance that limits its application scope,so it needs to be modified.In this study,bone repair materials better mechanical properties were through human trace elements?Sr ions or Mg ions?doping HA,and compounded with PLA,GO or GP.In addition,HA can be compounded with titanium dioxide and GP to prepare environmental functional materials with good photocatalytic,adsorpyive and antimicrobial properties.The obtained samples were analyzed and studied by means of X-ray diffraction?XRD?,Fourier transform infrared spectroscopy?FTIR?,Raman spectroscopy?Raman?,field emission scanning electron microscopy?FESEM?,energy-dispersive X-ray spectroscopy?EDX?,scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?and transmission electron microscopy?TEM?.And the photocatalytic performance of HA/GP/TiO₂ samples was tested with methylene blue as the target of the photocatalytic degradation.Also,E.coli was used to evaluate the antibacterial properties of HA/GP/TiO₂ samples.Sr-doped hydroxyapatite/graphene?Sr HA/GP?composites were successfully synthesized with different Sr contents by one-pot hydrothermal treatment.The influence on the HA crystal size,grain shape,grain size distribution,and micromorphology of composite materials were studied with different Sr doping amount.The results have shown that HA crystals exhibited the morphology of short rod-like particles,and the Sr ions were successfully added into the HA lattice.And it exhibited good morphology when small amount of Sr ions was doped,while high concentration of Sr-doping not only impacted the crystallinity of HA,made its morphology changed,and produced the amorphous phase,but also made HA particles form the agglomeration.Meanwhile,the interface interactions between HA and GP in Sr-droped HA/GP composites appeared during the hydrothermal process and resulted in their respective structural changes.Mg doped HA/GO powder was synthesized by hydrothermal method and then Mg-doped HA/GO/PLA composite coatings were coated on stainless steel substrates?Type 304?using the spin-coating technique.The micromorphology and internal structure of the composite coatings were discussed and the mechanical properties and bonding strength were tested as well.The results showed that Mg ions have been successfully doped into the HA crystal lattice,however the concentration of Mg doping should be lower than 20%?molar ratio?.When the concentration of Mg is higher than 20%,the interplanar spacing will become smaller,and the lattice will be distorted,which causes GO defect density to increase.The atomic ratio of?Ca + Mg?/P in the composite coatings ranged between 1.65 and 1.70 that was close to the Ca/P theoretical value of 1.67 in the HA.The average tensile strength of the composite coating is 68.97 MPa,the bond strength is 13.51 MPa,and its the mechanical strength can satisfy clinical experimental requirements for bone repair.The phase composition of composite coatings does not change when PLA is introduced into HA coatings,no impurity phase is formed and the surface morphology shows uniform,porous structures.The HA/GP powder was synthesized by the method of chemical precipitation,and then hydroxyapatite/graphene/titanium dioxide?HA/GP/TiO₂?composite materials were prepared with different concentration of TiO₂ through sol-gel in-situ method.The morphology and structure of composite were analyzed with different content of titanium dioxide,and the composite materials were also carried on the photocatalytic and antibacterial experiments.Studies have shown that the complexes of titanium dioxide/hydroxyapatite apply on the surface of graphene like bubble,evenly coated with graphene.The degradation rate of 30mg/L methylene blue solution by HA/GP/TiO₂ composite irradiated under ultraviolet light for 150 minutes reached up to 94%.The reason of composite material showing good photocatalytic efficiency is mainly because GP nanosheets can quickly and efficiently export photoelectrons and HA shows good adsorption properties.In addition,HA/GP/TiO₂ composite materials have strong antibacterial properties under illumination.