Antibacterial Study Of Conjugated Polymer/Helical Polypeptides Polyisonitrile Hydrogel

Photodynamic therapy(PDT)and photothermal therapy(PTT)are widely used in antibacterial and antitumor treatments because of their advantages such as high specificity,low invasiveness,and low toxicity to normal tissues.Conjugated polymers have excellent photoelectric properties and are excellent photosensitizers for PDT and photothermal agents for PTT.Polyisocyanopeptides(PIC)is a kind of temperature response hydrogel with good biocompatibility,which is suitable for biomedical applications.Based on the advantages of PIC,PMNT and CPNs-TAT,PIC/PMNT/CPNs-TAT composite hydrogels with PDT and PTT synergistic therapeutic capabilities were constructed,which can improve the therapeutic effect and reduce the laser power,radiation dose and drug concentration.This thesis focuses on the design,preparation,characterization and antibacterial application of PIC/PMNT/CPNs-TAT composite hydrogels.The summary is as follows:The PIC hydrogels with excellent biocompatibility,PMNT with the ability to produce ROS and CPNs-TAT with excellent photothermal conversion ability were non-covalent assembly to obtain a PIC/PMNT/CPNs-TAT composite hydrogels,which has dual therapeutic effects of PDT and PTT.The presence of PIC hydrogel has enhanced the photothermal ability of PDPP and the ROS yield of PMNT.The interaction between PIC hydrogel PMNT and CPNs-TAT was studied by scanning electron microscopy(SEM)and rheological experiments.PMNT is combined with PIC hydrogel to form a complex,and CPNs-TAT is evenly dispersed in the spaces between the PIC hydrogel chains.The stress stiffness properties of PIC/PMNT/CPNs-TAT composite hydrogels are not affected by PMNT and CPNs-TAT.The synergistic effect of PDT and PTT of PIC / PMNT / CPNs-TAT composite hydrogel can improve the therapeutic effect and improve the shortcomings of high light power and high drug concentration in single PDT or PTT treatment.PIC/PMNT/CPNs-TAT composite hydrogels provide ideas for studying new composite antibacterial hydrogels.2.The ability of PIC/PMNT/CPNs-TAT composite hydrogel to kill bacteria and fungi was studied,found that PDT and PTT can synergistically increase antibacterial effect.The experimental results show that the PDT and PTT synergistic treatment of PIC /PMNT / CPNs-TAT composite hydrogel can kill more than 99% of E.coli and S.aureus,and has a highly effective killing effect.For A.niger it can only play a role in inhibiting growth(about 70%).The experimental results show that the PIC/PMNT/CPNs-TAT composite hydrogel has a highly effective killing effect on E.coli and S.aureus,and can only inhibit the growth of A.niger.The bactericidal ability of PIC/PMNT/CPNs-TAT composite hydrogel comes from two aspects.First,PMNT irradiated with white light can sensitize surrounding oxygen molecules to cytotoxic ROS.Second,when irradiated with NIR light,the PDPP encapsulated in the nanoparticles converts light energy into thermal energy to increase the temperature of the surrounding solution,and the bacteria die due to the thermal inactivation of the membrane protein.Combined with the excellent biocompatibility of PIC hydrogel,PIC/PMNT/CPNs-TAT composite hydrogel is very promising as a hydrogel dressing for treating bacterial infections in wounds.