Photothermal Responsive Drug Release And Photodynamic Antibacterial Studies Of Gold Nanorods/Ti₃C₂-based Hybrids Nanosheets

Nanomaterials possess many excellent properties because of the unique physical and chemical properties,which have been applied in various fields such as biomedicine.In this paper,the photothermal and photodynamic properties of Ti₃C₂nanosheets,gold nanorods（GNRs）and polydopamine（PDA）were used to prepare two kinds of nanomaterials with different properties.An in-situ growth approach was employed to combine GNRs with Ti₃C₂ nanosheets to prepare in-situ Ti₃C₂@GNRs.Based on in-situ Ti₃C₂@GNRs,Ti₃C₂@GNRs/PDA/Ti₃C₂ nanocarriers with excellent photothermal properties,photothermal stability,drug loading rate,p H/NIR dual responsive drug release performance and biocompatibility were prepared.Also,Ti₃C₂@GNRs/PDA hybrid nanoparticles with distinct synergistic photodynamic antibacterial properties were prepared in this paper.This thesis is divided into the following two parts.Firstly,Ti₃C₂@GNRs were obtained by in-situ growth of GNRs on the surface of Ti₃C₂ nanosheets.Due to the excellent photothermal synergy between GNRs and Ti₃C₂ nanosheets,Ti₃C₂@GNRs displayed high photothermal conversion efficiency（45.89%）.Next,in order to improve the drug loading rate of nanocarriers,Ti₃C₂nanosheets and Ti₃C₂@GNRs were combined by using the distinct adhesion of PDA to form sandwich-like Ti₃C₂@GNRs/PDA/Ti₃C₂ nanocarriers.In addition,the dispersibility and stability of Ti₃C₂@GNRs/PDA/Ti₃C₂nanocarriers in different media were significantly improved by modifying with SH-PEG-CH₃.The results of UV-Vis-NIR,XRD,FT-IR,XPS,SEM,TEM and AFM indicated the successful preparation of Ti₃C₂@GNRs/PDA/Ti₃C₂ nanocarriers.And the size of Ti₃C₂@GNRs/PDA/Ti₃C₂ nanocarriers was around 200-300 nm.GNRs were inserted between Ti₃C₂ nanosheets,which could better reflect the near-infrared（NIR）responsiveness of two-dimensional Ti₃C₂ nanosheets.In addition,there were significant synergistic photothermal effects between Ti₃C₂ and GNRs.Therefore,Ti₃C₂@GNRs/PDA/Ti₃C₂ nanosheets exhibited excellent NIR response properties.The high specific surface area of Ti₃C₂ nanosheets and the strong adhesion of PDA endowed Ti₃C₂@GNRs/PDA/Ti₃C₂ nanocarriers with high drug loading efficiency（95.88%）.Furthermore,due to the strongπ-πinteraction between Ti₃C₂@GNRs/PDA/Ti₃C₂ and DOX,Ti₃C₂@GNRs/PDA/Ti₃C₂ nanocarriers displayed p H/NIR dual responsive drug release properties under the NIR laser irradiation.Moreover,the results of cytotoxicity tests indicated that Ti₃C₂@GNRs/PDA/Ti₃C₂ nanocarriers possessed low cytotoxicity and excellent biocompatibility.Then,the application of Ti₃C₂@GNRs/PDA hybrid nanoparticles in the field of synergistic photodynamic antibacterial was evaluated.In order to obtain nanoparticles with better synergistic photodynamic antibacterial properties,Ti₃C₂@GNRs hybrid nanoparticles with smaller size was prepared by extending the ultrasonic time of Ti₃C₂@GNRs.Then,Ti₃C₂@GNRs were modified with SH-PEG-CH₃ to obtain highly stable Ti₃C₂@GNRs-PEG.Finally,DA self-polymerized on the surface of Ti₃C₂@GNRs to form Ti₃C₂@GNRs/PDA hybrid nanoparticles under alkaline conditions.In addition,Ti₃C₂@GNRs/PDA hybrid nanoparticles with different PDA contents were prepared by changing the concentration of DA.The successful preparation of Ti₃C₂@GNRs/PDA hybrid nanoparticles was verified by the results of FESEM,TEM,UV-Vis-NIR,Zeta potential,XPS and FT-IR.And the size of Ti₃C₂@GNRs/PDA hybrid nanoparticles was around 100 nm.Subsequently,the photodynamic properties and synergistic photodynamic antibacterial properties of Ti₃C₂@GNRs/PDA hybrid nanoparticles were investigated.The results indicated that inserted GNRs between Ti₃C₂ could effectively prevent the aggregation of two-dimensional Ti₃C₂ nanosheets,ensuring the excellent photodynamic properties of Ti₃C₂ and PDA.Therefore,Ti₃C₂@GNRs/PDA hybrid nanoparticles exhibited enhanced synergistic photodynamic properties.With the increase of PDA content,Ti₃C₂@GNRs/PDA could produce more amounts of ¹O₂.In the absence of antibiotics,Ti₃C₂@GNRs/PDA hybrid nanoparticles showed excellent synergistic antibacterial properties against both E.coli and S.aureus,exhibiting great potential in antibiotic-free antibacterial activities.