The Construction Of Gold/Silver Nano-hybrid For The Treatment Of Multi-drug Resistant Bacteria Infection

Objective:The widespread use and unreasonable application of antibacterial drugs have made bacterial multidrug resistance a prominent problem that threatens human health.This study intends to use antibacterial peptides and hyaluronic acid modified gold/silver hybrid nanocages to construct a new type of targeted photothermal therapy antibacterial nano-preparation in order to overcome bacterial multidrug resistance and improve antibacterial effect and safety.Methods:Quasi-spherical silver nanoparticles(Ag nanoparticles,Ag NPs)and gold-silver hybrid nanocages(Au/Ag NCs)were prepared by seed growth and redox methods,and then conjugate with AP(P)via covalently bonded(Au-S)and hyaluronic acid(HA)via electrostatic adsorption to form an effective targeted antibacterial hybrid HA-P(Au/Ag).The properties of HA-P(Au/Ag)were characterized by ultraviolet spectrometer(UV-Vis),nanometer particle size,and zeta potential analyzer.The morphology was scanned by transmission electron microscope(TEM)and the X-ray photoelectron spectroscopy(XPS)was used to test the form of Au-S Bond.The stability of HA-P(Au/Ag)was tested in 4? storage conditions and MHB by monitoring changes in particle size and zeta potential.The photothermal effect was tested using a 808 near-infrared laser irradiator(NIR).MIC and MBC values of Au/Ag NCs,P(Au/Ag)and HA-P(Au/Ag)and NIR on multidrug-resistant Acinetobacter baumannii(MDR-AB)were evaluated by broth dilution method.The sterilization effect of MDR-AB was measured by time sterilization kinetics method and the antibacterial mechanism was investigated by the fluorescence intensity changes of the fluorescent dyes PI and NPN.The morphological changes of of MDR-AB was observed using scanning electron microscope(SEM).The cytoxicity was tested on human umbilical vein vascular endothelial cells(HUVECs)by CCK8 method and red blood cells by measuring the hemolytic rate.The effect of warming in vivo under NIR irradiation is scanned through thermal infrared imaging,the antibacterial effect in vivo was comprehensively evaluated by MDR-AB infected mouse pneumonia model.Results:The experimental results of UV-Vis,nanometer particle size,zeta potential analyzer,TEM and XPS showed that the experimental scheme successfully synthesized antibacterial hybrid Au/Ag NCs,P(Au/Ag)and targeted antibacterial hybrid HA-P(Au/Ag).The results of stability experiments show that HA-P(Au/Ag)can be stored at 4? for at least 5 days,and keep stable in MHB medium solution for at least 8 hours.After NIR irradiation,the solution temperature rises significantly within 5 min,and is then maintained at about 45?.The measured MIC and MBC values showed that Au/Ag NCs,P(Au/Ag)and HA-P(Au/Ag)have good antibacterial activity against MDR-AB,and the MIC and MBC values have decreased under NIR irradiation,indicating that the antibacterial activity was further improved under photothermal treatment.The results of time sterilization kinetics experiments showed that HA-P(Au/Ag)under NIR irradiation can quickly kill MDR-AB at a concentration of 6?g/mL,and HA-P(Au/Ag)required 12?g/mL to achieve the same effect.The results of SEM and fluorescence studies indicated that the antibacterial nano-preparation mainly destroys the biofilm and morphology of MDR-AB to leak the contents of the bacteria and completely kill the bacteria.The cytotoxicity and hemolysis experiments showed no cytotoxicity to HUVECs and no effect toxicity to red blood cells.After giving a certain treatment to the pneumonia model mouse the results show that HA-P(Au/Ag)under NIR irradiation has better activity in vivo and is relatively small toxic in mice with great biocompatibility.Conclusion:The targeted antibacterial hybrid HA-P(Au/Ag)constructed in this study significantly improved the antibacterial activity of individual components in vitro and in vivo,reduced toxic side effects in vivo,and made the survival rate of MDR-AB infected pneumonia model mice significantly improved.Therefore,targeting antibacterial hybrid HA-P(Au/Ag)is an efficient and safe treatment strategy,which is expected to provide a new safe and effective research method for the treatment of multidrug-resistant bacteria.