Preparation Of Porphyrin-polypeptide Self-assembly System For Antibacterial Treatment

The death and injury of personnel caused by bacterial infections and the occupation of social resources have caused great distress to humans.The use of antibiotics such as penicillin and cephalosporin to a large extent help people treat bacterial infections.However,with the excessive use of antibiotics,drug-resistant bacteria were screened and their types and numbers increased year by year.Some drug-resistant strains evolved into super bacteria,which seriously threatened human health.Therefore,with the advent of the "post-antibiotic" era,the development of new antibacterial therapy is an effective way to prevent and treat antibiotic-resistant bacteria.Photodynamic antibacterial therapy and sonodynamic antibacterial therapy are new antibacterial therapies based on reactive oxygen species(ROS)killing bacteria.They have the advantages of non-invasiveness,no antibiotics,low toxicity,and no screening for bacteria,which has attracted widespread attention.The key to photodynamic antibacterial treatment is the development of new high-efficiency photosensitizers,and the metal porphyrin assembly nanoparticles have a wide range of light absorption in the visible light region due to their highly conjugated structure,and a higher singlet oxygen quantum yield.Such advantages,as a class of ideal high-efficiency photosensitizers.However,due to the shallow depth of light tissue penetration,it is only suitable for the treatment of surface bacterial infections.Therefore,in deep bacterial infections,sonodynamic therapy has received increasing attention due to its better penetration depth.However,how to concentrate the sonosensitizers at the site of infection and realize the in situ observation of the concentration of the sonosensitizers to achieve the optimal therapeutic concentration is the focus of the current development of sonodynamic therapy.In response to the above issues,we conducted the following two aspects of research:1.Using acid-base neutralized micelle-bound self-assembly method,adjusting the reaction conditions such as the pH in the reaction solution,the type and concentration of the emulsifier,the reaction temperature,controllable preparation of uniformly-sized,regular structured zinc porphyrin self-assembly Nanoparticles,using the coordination of Zn and NO,effectively adsorbed NO to prepare ZnTPyP@NO nanoparticles.Through infrared spectroscopy(IR)and thermogravimetric analysis(TGA),it was proved that the amount of nitric oxide adsorbed by ZnTPyP self-assembled nanoparticles was ~20% wt.At the same time as achieving high loading,the ZnTPyP@NO nanoparticle has almost no change in the amount of nitric oxide adsorbed after storage for six months under normal temperature,atmospheric pressure,and light conditions,which overcomes the severe requirements of the traditional carrier for supporting nitric oxide(such as negative 20 °C,vacuum environment),greatly facilitate the preservation,transportation and use of materials.ZnTPyP@NO nanoparticles not only produce ROS,but also release nitric oxide under light conditions.The two interact synergistically to produce peroxynitrite ions,which can kill bacteria with high efficiency.The results of antibacterial experiments showed that ZnTPyP and ZnTPyP@NO nanoparticles showed extremely low dark toxicity.After the light conditions were added,ZnTPyP and ZnTPyP@NO nanoparticles exhibited good bactericidal effect.ZnTPyP@NO released nitrous oxide at the same time as it can produce active oxygen,and also produced peroxynitrite,so the bactericidal effect of ZnTPyP@NO nanoparticles was significantly better than that of ZnTPyP nanoparticles.2.We designed a porphyrin-polypeptide deformable self-assembling nanosystem M1,M1 containing the sonosensitizer MnTCPP,bacterial targeting peptide CGGGTGRAKRRMQYNR,hydrophobic partially hyperbranched bis-MPA polyester-64-hydroxyl,gelatinase responsive segment and hydrophilic segment KLVFFPLGVRG-PEG2000.M1 forms spherical nanoparticles of size 10-40 nm in aqueous solution and accumulates effectively at sites of bacterial infection through EPR(Enhanced permeability and retention effect)effects.The PEG protecting group was excised under the action of gelatinase at the site of bacterial infection.At the same time,due to the guidance of the targeting peptide,the sensitizer MnTCPP was targeted to deposit on the surface of the bacteria.In addition,with the removal of the PEG protecting group,the hydrophilicity of the nanoparticle decreases,the assembly deformation is induced by the deformed peptide KLVFF,and the nanomaterial self-assembles in situ on the bacterial surface through the AIR(Assembled-induced retention)effect.MnTCPP is more efficiently retained at the site of infection,overcoming the problem that the residence time after conventional nanoparticle enrichment is relatively short.In addition to being introduced as a sonosensitive agent,MnTCPP can also be used as a nuclear magnetic imaging agent to monitor the cumulative amount of drug at the site of bacterial infection and enable in situ monitoring.We used in vitro antibacterial experiments to discover the MIC,and then calculated the cumulative amount of material at the site of bacterial infection by monitoring the magnetic imaging signal in a live infection model.Ultrasound treatment was performed when the material concentration was just greater than the MIC.Thorough treatment of MRSA(methicillin-resistant Staphylococcus aureus)deep infection.This material realizes the in-situ monitoring and acoustic therapy of deep resistant infections,providing a new idea for the precise treatment of deep resistant infections.