Surface Modification Of Titanium With Hydroxyapatite Layer Induced By Phase-transited Lysozyme Coating

purpose: With the development of oral implant technology,dental implant repair has become the main repair method for dentition defect.Because of its good biocompatibility,pure titanium has become the most widely used implant material for clinical application.However,pure titanium,as an inert material,has poor biological activity.Therefore,many studies have improved the bio-inertness of pure titanium implants by modifying the implant surface.Among them,hydroxyapatite coatings have become the most widely used implant surface modification technology in recent years for they can significantly increase the biological activity of titanium implants.However,the methods for preparing the hydroxyapatite coating technology reported so far are relatively complicated,the manufacturing conditions are harsh,and the manufacturing cost is high.Therefore,it has become an urgent need to find a simple,effective and rapid method for preparing a hydroxyapatite coating.In this dissertation,a phase-shifted lysozyme was used as a template to utilize its abundant functional groups to mimic the process of biomineralization in vitro,a uniform and dense layer of hydroxyapatite was formed on the surface of pure titanium in the form of biomimetic mineralization.method: 1.adjust the concentration of lysozyme,reducing agent tris(2-carboxyethyl)phosphate hydrochloride TCEP PH value,and the various diameters of titanium plate after grinding then were immersed in the above two solution mixture,remove After incubation for 2 hours,PTL-modified titanium pieces were prepared.The PTL-modified titanium plate is immersed in Ca Cl2 solution to complete the process of chelating calcium ions by utilizing the abundant functional groups contained on the surface of the lysozyme phase transformation product(PTL),and further immersed in artificial body fluid(SBF)according to electrostatic attraction interaction,the process of biomineralization was simulated in vitro,and hydroxyapatite coating was successfully prepared on the surface of the titanium sheet.2.Each group of titanium tablets were characterized respectively.Scanning electron microscopy(SEM),transmission electron microscopy(TEM),energy dispersive X-ray spectrometer(EDX),high resolution X-ray polycrystal diffraction(XRD),X-ray photoelectron spectroscopy(XPS),AIR-FTIR,and Raman spectrometer were used to observe and analyze the surface morphology,Nature and elemental composition of the hydroxyapatite biocoatings with phase-shifted lysozyme templates Nature and elemental composition.3.Rat bone marrow mesenchymal stem cells(BMSCs)were cultured in vitro,and their biocompatibility was evaluated by setting them on the surface of the titanium plate modified by hydroxyapatite biocoating.The activity of the cells was measured by the CCK-8 method and the confocal microscopy was used to observe the morphology of the osteoblasts on the surface of the titanium plate and its adhesion and proliferation.The AKP test kit was used to test the alkaline phosphatase(ALP)activity of the surface cells.The hydroxyapatite biocoated titanium sheet was implanted into rat skin to observe the hydroxyapatite prepared by this method.Osteoinductive and osteoinductive.result:1.XPS results show that the surface of the PTL-modified titanium sheet has abundant functional groups(carboxyl,hydroxyl,etc.).Provides rich active sites for biomineralization of hydroxyapatite.XPS results after soaking in Ca Cl2 solution showed that the PTL-modified titanium sheet could chelate and fix calcium ions,providing nucleation sites for further mineralization of hydroxyapatite.Therefore,XPS results after immersing in SBF solution for 5 days showed that a uniform dense hydroxyapatite coating was formed on the surface of the PTL-modified titanium sheet.2.Through scanning electron microscope(SEM),transmission electron microscope(TEM),energy dispersive X-ray spectrometer(EDX),high-resolution X-ray polycrystal diffractometer(XRD),X-ray photoelectron spectroscopy(XPS),infrared spectrum test(AIR FTIR)and Raman spectrometer further confirmed that hydroxyapatite coating was actually formed on the surface of the PTL modified titanium sheet,which is similar with the natural bone and the composition of hydroxyapatite in teeth.3.The results of a series of cell experiments show that the hydroxyapatite-modified titanium sheet has good biocompatibility,and the cells spread well on the surface and are superior to the pure titanium group.The experimental results of ALP and ectopic bone formation indicate that the hydroxyapatite-modified titanium sheet has better bone conduction and osteoinduction than the pure titanium group.Conclusion: The basic modification of pure titanium surface was completed by the good adhesion of phase-transfer lysozyme(PTL)and a large number of functional groups on its surface,and provided basis for the further preparation of hydroxyapatite coating.According to the electrostatic attraction interaction,the biomineralization process was simulated in vitro and the hydroxyapatite coating was successfully prepared on the titanium surface.The technical process is simple,rapid,environmental and mild,and the prepared hydroxyapatite coating has controllable morphology and stable mechanical properties.It is expected that the clinical transformation will become a new type of implant surface modification technology.