Amyloid Peptide Assembly Confined Nanostructures And Photothermal Antibacterial Study

At present,bacterial drug resistance has become a world-wide problem,seriously threatening human life,health and safety.As a non-invasive and efficient local antibacterial method,photothermal therapy has shown broad application prospects in the field of multi-drug resistant bacteria and wound recovery..The design of a photothermal agent with high efficiency,high biological safety and strong bacterial adhesion is the prerequisite for expanding its application in the field of photothermal sterilization.Compared with other gold nanostructures,small-sized gold nanoparticles(AuNPs)have poor near-infrared photothermal performance,but have higher biological safety.How to enhance the photothermal performance of small-sized AuNPs is an urgent problem in this field.In this paper,the multi-level self-assembly template of amyloid peptides is used to restrict the domain control of AuNPs,and AuNPs-amyloid peptide nanocomposites are synthesized by in-situ reduction.While preparing small-sized AuNPs by simple steps,their biological safety is improved and their biosafety is enhanced.Thermal performance in the NIR region.At the same time,the good interaction between the amyloid polypeptide template and the bacteria is used to enable the AuNPs-amyloid polypeptide nanocomposite to obtain a better photothermal sterilization effect.The main research content are as follows:1.Near-infrared photothermal antibacterial research on Core/shell structural ultra-small gold and amyloid peptide nanocomposites.In this experiment,a new gold-amyloid polypeptide(A?25-35)nanocomposite(Au@A? NCs)with a core/shell structure was constructed using gold nanoparticles.Take ultra-small gold nanoparticles(ca.4.0 nm)as the core,and A?25-35 oligomers(ca.3 nm thick)as the shell.Compared with pure gold nanoparticles,Au@A? NCs nanocomposites show enhanced near-infrared absorption and light-to-heat conversion efficiency,which is due to the ? shell layer of gold nanoparticles.In addition,Au@A?NCs can adhere to bacteria very well and gather together through the inherent self-assembly properties of amyloid peptides,which facilitates local photothermal ablation of bacteria.2.Amyloid Peptide Hierarchical Assembly Confined Au Nanoparticles for Enhanced Antibacterial Photothermal Lysis.Using human amylin peptides(SNNFGAILSS,hIAPP20-29)with different morphologies of hierarchical assemblies(oligomers,fibers,ribbon)as templates,in situ reduction of Au nanoparticles(AuNPs)to prepare amyloid The Au-amyloid polypeptide nanocomposite(hIAPP20-29@Au)with polypeptides conjugated with AuNPs,because the hIAPP20-29 self-assembled template and the double-layer phospholipid molecular membrane have a special interaction that intersperses but does not break the membrane,hIAPP20-29@Au can better combine with bacteria.Compared with the original AuNPs,hIAPP20-29@Au,its local surface plasmon resonance(LSPR)absorption peak has changed,and an absorption band appears at 808 nm,so it shows better near-infrared photothermal sterilization performance.And has better biocompatibility.3.Insight into Apoptosis-like Bacterial Death Modulated by Photoactive Hyperthermia Nanomaterials.In this work,we tried to use the combination of STOY9/PI staining method and plate culture counting method to gain insight into the bacterial death process caused by PTT.The core-shell Au@SiO2 nanorods were used as the model "nano heater",and E.coli(E.coli)is a model bacteria.In continuous PTT,the micromorphology of the cell membrane surface changes dynamically,rather than the direct destruction of the outer cell membrane,but causes the micromorphology of the cell membrane surface to change from smooth to rough/uneven and dynamic.Then phase separation occurs.Therefore,the microbial activity of E.coli can change dynamically,from live to apoptosis(45-55?),then to apoptosis/necrosis(about 58?),and finally to necrosis(>60?).Based on this,we can completely kill bacteria through apoptosis or similar necrosis according to the temperature adjusted by PTT.Therefore,in the treatment of wound infection,although the PTT temperature is 50?,the healing effect of PTT is better than that of 58?.This is because although they have similar bactericidal ability,they have lower temperature and apoptosis.Bacteria in the state are less harmful to normal tissues.