Two-dimensional Ti₃C₂T_x-PEG/Ag Composites For Photodynamic Antibacterial Properties

In recent years,the emergence of drug-resistant bacteria has seriously threatened human health.At the same time,microbial infection has always been a major problem that urgently needs to be resolved in the medical field.Therefore,it is urgent to design a new type of antibacterial material that is highly efficient and does not easily develop drug resistance.Two-dimensional Ti₃C₂T_x has received extensive attention in the field of antibacterial materials for its high specific surface area,strong photodynamic performance and low biological toxicity.In this paper,bulk Ti₃Al C₂ is used as raw material.Firstly,Ti₃C₂T_x-PEG material which could stably exist in aqueous solution is prepared via hydrofluoric acid(HF)etching,ultrasonic peeling and surface modification.Then,Ti₃C₂T_x-PEG/Ag composites was prepared by loading with silver nanoparticles(Ag NPs),which has uniform distribution of silver nanoparticles with a particle size of about 12 nm.Finally,the photodynamic synergistic antibacterial performance has been systematically studied.The specific research content and results are as follows:(1)Multiple layer-Ti₃C₂T_x(ML-Ti₃C₂T_x)with good layering morphology was prepared by HF etching method,and the aluminum atomic layers in Ti₃Al C₂ are etched and removed in this process.Next,dimethyl sulfoxide(DMSO)was introduced as the intercalating agent,and few layer-Ti₃C₂T_x(FL-Ti₃C₂T_x)was successfully exfoliated by stirring and water bath ultrasound.Then the surface modification of FL-Ti₃C₂T_x was carried out to convert hydroxyl groups on its surface to carboxyl groups(Ti₃C₂T_x-COOH).Finally,the hydrophilic hydroxy-terminated polyethylene glycol(PEG-OH)was connected to its surface through esterification reaction to made Ti₃C₂T_x-PEG.Compared with FL-Ti₃C₂T_x,the stability in aqueous solution of Ti₃C₂T_x-PEG was greatly improved.(2)Using Ti₃C₂T_x-PEG and silver nitrate(Ag NO₃)as raw materials,sodium hydroxide(Na OH)as a reaction accelerator,and adjusting the mass ratio of feed materials(Ti₃C₂T_x-PEG:Ag NO₃)and microwave reaction time to control the particle size and distribution of Ag NPs on Ti₃C₂T_x-PEG.The analysis results show that when the microwave power is 210 W,the feed mass ratio is 1:1,and the microwave reaction time is 60 s,the Ti₃C₂T_x-PEG/Ag composites with the best loading state can be prepared,and the Ag NPs are uniformly distributed with particle size about 12 nm.(3)The photodynamic property of Ti₃C₂T_x-PEG/Ag was characterized by 1,3-diphenylisobenzofuran(DPBF),and the photodynamic synergistic antibacterial property of the composite were systematically studied.Using clinically common gram-negative bacteria,Escherichia coli(E.coli)and gram-positive bacteria,Staphylococcus aureus(S.aureus)as a model system to study the photodynamic synergistic antibacterial property of the composites,its antibacterial mechanism is also analyzed.The experimental results show that the UV-vis peak of DPBF at 410 nm is reduced to67.4%after irradiated with 660 nm laser for 30 min,which means Ti₃C₂T_x-PEG/Ag composites produces a large amount of singlet oxygen(¹O₂)under light,indicating that Ti₃C₂T_x-PEG/Ag composites owns excellent photodynamic properties.The antibacterial test results showed that the minimum inhibitory concentrations of Ti₃C₂T_x-PEG/Ag composite materials against E.coli and S.aureus was reduced to 1.56?g/m L under 660 nm laser.And Ti₃C₂T_x-PEG/Ag composite materials mainly achieve its excellent photodynamic synergistic antibacterial properties through the encapsulation of Ti₃C₂T_x-PEG layer,the puncture effect of Ag NPs and ROS-induced oxidative damage.