The Experimental Study Of Minocycline Loaded On The TiO₂ Nanotubes In Vitro

Peri-implantitis is considered to be one of the main reasons for failure of oral implant repair.Therefore,how to improve the antibacterial performance of titanium implants,reducing the occurrence of peri-implantitis,has become a current research hotspot.With the development of implant surface modification technology,building a local drug release system on the surface of nano-structured titanium implants has attracted widespread attention.Ti O₂nanotubes have the characteristics of large specific surface area,porous and uniform structure,neat arrangement,closed bottom,etc.and can be used as good carriers for adsorbing drugs.In this study,three kinds of Ti O₂nanotubes with different diameters were prepared on the surface of titanium substrate by anodic oxidation method,loaded with minocycline hydrochloride and combined with chitosan multilayer film to construct an antibacterial coating structure.Through the characterization and analysis of the drug-loading ability and sustained release characteristics of Ti O₂nanotubes with different tube diameters,the optimal structure of the diameter of the titanium dioxide nanotubes was obtained;and in vitro bacteriostatic experiments were performed to confirm that minocycline-loaded Ti O₂nanotube composite coating had a good inhibitory effect on P.gingivalis.It provides a new method for the research of antibacterial coating on the implant surface,and provides new ideas for the prevention and clinical diagnosis and treatment of peri-implantitis.The specific experiment content is as follow:The first part:Treatment of Titanium Sheets and Preparation of Titanium Dioxide NanotubesMethods The titanium foil is processed into a round smooth titanium piece having a diameter of 15 mm and a thickness of 0.25 mm.The anodic oxidation method was used to adjust the voltage of the DC stabilized power supply to prepare Ti O₂nanotubes with diameters of 30,70 and 120nm,respectively.The morphological characteristics of pure titanium flakes and three kinds of tube diameter Ti O₂nanotubes were observed by FESEM.Results The smooth titanium sheet is mirror-like and the surface of Ti O₂nanotubes is honeycomb,the diameters of the titanium nanotubes are about 30nm,70nm,and 120nm,respectively,and the cross-section shows that the heights of the titanium nanotubes with different diameters are about 700nm.The second part:Ti O₂nanotubes loaded with minocycline hydrochloride and chitosan multilayerMethods The freeze-drying method was used to load minocycline hydrochloride on the surface of Ti O₂nanotubes at 30,70,120nm.Chitosan multilayers loaded on Ti O₂nanotubes by spin coating.The samples were characterized by Field emission scanning electron microscopy,contact angle measurement,X-ray diffraction,Fourier transform infrared spectroscopy and UV-Visible spectrophotometer,To test the effect of minocycline hydrochloride on the surface of Ti O₂titanium nanotubes with differenttube diameters.Results Field emission scanning electron microscopy showed that after loading minocycline hydrochloride,the pores and the pores between the nanotubes were filled with drugs,but the tubular morphology remained.After being covered with multiple layers of chitosan,the appearance of nanotubes disappeared and the surface was smooth and flat.The contact angle test showed that the contact angle of the Ti O₂nanotube group was significantly lower than that of the pure titanium group,showing good hydrophilicity,and the larger the tube diameter,the smaller the contact angle,and the greater the hydrophilicity.The hydrophilicity of titanium nanotubes loaded with minocycline hydrochloride decreased,and the hydrophilicity decreased significantly after covering chitosan.XPS test showed that N,C,Cl elements increased significantly after drug loading,FTIR detection showed that after loading the drug,the band at3000cm^-1was the characteristic line of the benzene ring,and 1498cm^-1was the characteristic band of the benzene ring skeleton C=C,which was consistent with the structural formula of minocycline hydrochloride.Confirmed that the surface of the experimental group was successfully loaded with minocycline hydrochloride.The release curve of minocycline hydrochloride showed that the drug loading capacity of the70nm Ti O₂nanotube group was the largest,and there was still a small amount of release by the 15th day,indicating that the 70nm Ti O₂nanotube group had a slower release ability than the other two groups.The third part:Inhibition of Porphyromonas gingivalis by titanium dioxide nanotubes loaded with minocycline hydrochlorideMethods Under anaerobic conditions,the Ti O₂nanotubes loaded with minocycline hydrochloride were placed in a blood plate containing Porphyromonas gingivalis for48-72h,and the presence of bacteriostatic rings was observed at the edges of the material.The concentration of Porphyromonas gingivalis bacterial suspension was measured at a certain time node to evaluate the antibacterial effect of the material.Results The antimicrobial coating of titanium dioxide nanotube-minocycline hydrochloride has certain antimicrobial ability.Conculsion To test the drug-loading capacity and sustained release characteristics of minocycline hydrochloride loaded into Ti O₂nanotubes with different tube diameters.Among them,70nm Ti O₂nanotubes have the largest drug loading,the best sustained-release effect,and good inhibitory effect on Porphyromonas gingivalisa,which is expected to enhance the antibacterial effect of titanium surface.