Antibacterial Properties Of TiO₂ Nanorod Arrays Modified With Carbon-based Nanomaterials On The Surface Of Titanium Implants

Titanium（Ti）is widely used as an implant material in orthopaedics and dentistry due to its good biocompatibility,corrosion resistance and mechanical properties.However,Tiimplant-associated infections are still prevalent in clinical practice.Post-operative infections can be effectively addressed by introducing inorganic antimicrobial agents（Ag,Cu,Zn,etc.）to the Tisurface or by constructing antimicrobial nanostructures,but the toxicity of heavy metal ions and the low antimicrobial capacity of nanostructures limit their clinical application.Carbon-based nanomaterials（such as carbon dots and graphene quantum dots）have received much attention due to their high biocompatibility and unique physicochemical properties.Carbon-based nanomaterials also possess antibacterial properties and have broad application prospect in antibacterial applications.Herein,TiO₂ nanorods array（TiO₂ NR）was firstly constructed on Tisurface by hydrothermal treatment,and then modified with biocompatible carbon dots（CDs）and graphene quantum dots（GQDs）,respectively.TiO₂ NR modified with CDs endows Tiimplant with high-efficiency photo-assisted antibacterial activity,while TiO₂modified with GQDs NR make Tiimplant have excellent contact-killing ability.The main research contents are as follows:（1）CDs modified TiO₂ NR（C-TiO₂ NR）was prepared by a secondary hydrothermal treatment in a dispersion of CDs.The microstructure of C-TiO₂NR was characterized by X-ray photoelectron spectroscopy（XPS）and Fourier transform infrared spectroscopy（FTIR）,which confirmed that CDs is successfully doped in the TiO₂ NR surface.The contact angle test results show that C-TiO₂ NR has good hydrophilic properties.C-TiO₂ NR has good photocatalytic properties under the irradiation of 660 nm light and exhibits excellent photothermal properties under the irradiation of 808 nm light.Under co-irradiation of dual light（660 nm+808 nm）,C-TiO₂ NR shows excellent in vitro and in vivo antibacterial ability against S.aureus within 15min due to the synergistic effect of thermal therapy,reactive oxygen species（ROS）and nanorod structure.In addition,cellular experiments show that C-TiO₂ NR can also promote the adhesion and spreading of bone marrow mesenchymal stem cells.（2）GQDs modified TiO₂ NR（G-TiO₂ NR）was prepared by a secondary hydrothermal treatment in a dispersion of GQDs.The results show that TiO₂ NR is successfully modified by GQDs.G-TiO₂ NR can trap bacteria by electrostatic adsorption,and then the combined effect of histidine-functionalized GQDs and nanorod puncture make G-TiO₂ NR possess excellent in vitro and in vivo contact antibacterial ability against S.mutans within 24 h.Cytoskeleton experiments confirm that G-TiO₂ NR has good biocompatibility.In addition,animal experiments show that G-TiO₂ NR can effectively promote the formation of new bone under the condition of controlling infection.