Design And Study On Near-infrared-Triggered Drug Delivery Systems Based On TiO₂ Nanotube Arrays/Black Phosphorus

Titanium and its alloys are good choices for orthopedic implants,however,their antibacterial activity and bone integration ability are dissatisfied,which may bring some problems such as bacterial infection or tissue inflammation after implantation,ultimately leading to implantation surgery failure.Constructing a local drug delivery system on a titanium-based implant,is considered to be an effective solution to solving the above problems.TNTs prepared by electrochemical anodization on Ti-base implants,is an ideal carrier for various drugs or other active molecules due to hollow tubular structures.Unfortunately,the drug release from TNTs is uncontrollable,and burst release occurs in the initial stage.Therefore,it is essential to design a drug delivery system that can quickly respond to the external stimulus,achieving the controlled drug release.Near-infrared light is a safe and controllable external stimulation,which has been widely used in triggering drug delivery.Thus,in this study,based on the photothermal effect of black phosphorus under near-infrared light irradiation and the ability to produce reactive oxygen species under specific wavelength laser irradiation,three light-triggered drug release strategies based on TNTs were proposed:Firstly,nanoscale BP was prepared using a liquid exfoliation method and incorporated with TNTs by electrophoretic deposition.The TNTs-BP complex not only exhibits excellent photothermal conversion properties,but also enhanced biomineralization.In order to avoid unexpected drug loss,a thermosensitive coating,1-tetradecanol（TD）was introduced on the TNTs-BP complex,acting as a gatekeeper.Under the exposure of near-infrared light,the temperature of the system significantly increased,resulting in the melting of the coating and the quickly drug release.Secondly,BP was encapsulated in a thermo-sensitive gel to prepare a near-infrared light sensitive hybrid,the hybrid was then coated on the drug-loaded carrier.The coating would cause a slower drug release.When exposed to NIR light,the temperature of the system increased,which lead to the shrinkage of the gel and rapidly drug release.Thirdly,BP was encapsulated in a ROS-sensitive gel to prepare a light sensitive complex.Under the exposure of 660 nm laser,it can generate singlet oxygen（¹O₂）,which could not only cause the disintegration of gel,but also have antibacterial activity.The BP-encapsulated gel was coated on the drug-loaded TNTs,which can be served as a gatekeeper as well as an antibacterial coating.