Study On The Multi-mode Synergistic Antibacterial Materials Based On Photothermal Effect

Due to the high mortality rate of diseases caused by harmful bacteria infection,it is one of the main causes of death for residents in undeveloped countries and regions.Most of the existing antibacterial strategies depend on antibiotic treatment.However,the overuse of antibiotics leads to the increasing bacterial resistance and causes a serious threat to human health.Photothermal therapy is a method of killing bacteria by using near-infrared radiation(NIR)to produce high temperature in local tissues.NIR can penetrate deep tissues and kill bacteria in a broad-spectrum,safe and effective way.Based on the photothermal effect,this work combined photothermal therapy with antibiotic or cationic polymers to achieve multi-mode coordinated antibacterial.The new strategies are supposed to improve the antibacterial efficiency.1.The preparation and antibacterial properties of antibacterial nanofiber membrane based on photothermal effect and drug synergistic treatment.Firstly,PCL,PMMA,PANI and ROX were mixed in a certain proportion to obtain drug-loaded nanofiber membrane by electrospinning.The chemical composition,physical morphology and wettability of the nanofiber membrane were characterized by FT-IR,SEM and CA analysis.The drug releasing behavior and bactericidal performance of the nanofiber membrane were also studied.The experimental results show that the composite nanofiber membrane has uniform fiber distribution and good hydrophilicity.The drug loading ratio is about 13%.the nanofiber membrane has excellent photothermal effect,which can be heated up to 20? after 1 min of NIR irradiation.By adjusting the proportion of PCL and PMMA,the drug release rate increases significantly when the membrane is heated up,and the ROX releasing rate reaches 55%at 6 h.Under the synergistic effect of photothermal and antibiotic,the bactericidal ratio towards S.aureus was 99%.Since NIR is an exogenous control method,it can realize the accurate control of the time,position and dose of drug release.In this work,the photothermal effect and the precise drug release are successfully combined to achieve the synergistic antibacterial therapy.2.Study on the preparation and antibacterial properties of pH-responsive multilayer with photothermal effect.Polyanion(PAA)and polycation(QCS)were self-assembled through electrostatic force to obtain polymeric multilayer.In acid condition,the multilayer is positively charged due to the protonation of amino groups,and become negatively charged due to the deprotonation at pH=7.4.By changing the assembly pH,molecular weight and top-layer polymer,the key factors affecting the surface charge and isoelectric point(IEP)of the multilayers were discussed.When the pH-responsive multilayers were obtained,gold nanoparticles(AuNPs)having photothermal effect were further assembled into them.The multilayers were characterized by atomic force microscopy(AFM),ellipsometry,zeta potential analysis and energy dispersive spectroscopy(EDS).The pH responsibility,photothermal effect and antibacterial properties of the multilayers were further studied.The results show that the AuNPs are successfully assembled into the multilayers and distributed uniformly.The AuNPs-loaded multilayers can be heated up to 60? in 5 min under NIR irradiation,showing a good photothermal property.The multilayers shrink(thickness is 546 nm)and positively charged at pH 5.0,whereas they swell(thickness is 662 nm)and negatively charged at pH=7.4.The IEP is 6.0?6.2.On the other hand,due to the volume shrinkage of multilayers and thereby the aggregation of AuNPs,the photothermal effect is enhanced under acidic conditions.Under the synergism effect of photothermal and cationic polymer,the bactericidal ratio of S.aureus achieved nearly 100%.The multilayer show a good biocompatibility at pH=7.4 and without NIR irradiation.In this work,the variation of microenvironment acidity of bacteria infected site and NIR regulated photothermal effect are utilized to realize the efficient,safe and synergistic antibacterial treatment.Our study provides a new idea for the non-antibiotic bactericidal strategy.