Preparation Of Anti-Resistant Staphylococcus Aureus Nanomaterials And Its Antibacterial Performance Study

Drug-resistant Staphylococcus aureus(S.aureus)is a typical gram-positive bacterium,and also a zoonotic pathogen,which seriously affects the safety of food raw materials.Due to the resistance of S.aureus has broad-spectrum drug resistance,many traditional antibiotics can not play a good therapeutic effect on the infection caused by it.Therefore,the development of antimicrobial materials that do not easily cause drug resistance is of great significance to ensure food safety.In recent years,researchers have begun to develop nano-antibacterial agents.Up to now,researchers have developed a variety of nanoantibacterial materials.However,antibacterial strategies based on nanomaterials have the following problems: many nano-antibacterial materials are cumbersome to prepare and have low yields;the use of toxic reagents in the preparation of nano-antibacterial materials results in poor biocompatibility,and harms to the environment.In view of the problems mentioned above,this paper has prepared highly efficient antibacterial materials by using nanomaterials as the core,and the antibacterial materials have the properties of good biocompatibility,environmental friendliness,and not easy to cause drug resistance.Subsequently,the antibacterial properties of the prepared against drug-resistant S.aureus were studied.The main contents are summarized as follows:1.Study on the antibacterial activity of carbon quantum dots against drug-resistant Staphylococcus aureus.Carbon quantum dots(N-CQDs)with good biocompatibility were prepared in this part,and the antibacterial activity and mechanism of N-CQDs against methicillin-resistant Staphylococcus aureus(MRSA)were studied.N-CQDs showed an excellent inhibitory effect on MRSA by growth curve method,plate coating method,and live/dead staining method.Meanwhile,drug-resistant test confirmed that N-CQDs were not prone to cause bacterial resistance.The antibacterial mechanism studies demonstrated that the oxidative stress generated by the positively charged N-CQDs destroyed the integrity of bacterial cell membrane and biofilm,and interfered with the normal metabolism of bacteria,leading to bacterial death.This study provides theoretical basis for the wider application of carbon quantum dots in the field of antibacterial.2.Study on thespecificrecognition and inactivationto drug-resistant Staphylococcus aureuswith functional gold nanostarsBased on the gold nanostars(Au NSs)have a high light absorption cross section and excellent light-to-heat conversion efficiency in the near infrared band,and vancomycin(Van)can recognize gram-positive bacteria,an antibacterial platform Au NSs@Van with recognition functon was prepared.SEM and TEM proved that Au NSs@Van had a good recognition effect on MRSA;plate count method and MRSA-infected mice models have exhibited that Au NSs@Van possessed excellent antibacterial activity both in vitro and in vivo.The antibacterial mechanism showed that Au NSs@Van destroyed the integrity of the bacterial cell membrane and caused the death of bacteria under the irradiation of nearinfrared(NIR)light.Additionally,Van in Au NSs@Van also had a certain antibacterial effect,enhancing the antibacterial activity of Au NSs@Van.However,Van's antibacterial effect was relatively weak,and Au NSs@Van was still mainly based on physical sterilization,hence,it reduced the possibility of bacteria developing resistance.The design of the antibacterial platform provides a certain theoretical guidance for the targeted treatment of bacterial infection.3.Study on the accurate photothermal therapyfor drug-resistant Staphylococcus aureus infection withacidity-triggered the aggregation of gold nanoparticlesBased on the microenvironment of bacterial infection,this part had designed a PepDA/Au acid-triggered intelligent antibacterial platform.The experimental results showed when Pep-DA/Au and MRSA were incubated in an acidic environment,the charge inversion of Pep-DA/Au became positively charged Pep-Au;the positively charged PepAu interacted electrostatically with the negatively charged bacterial surface and aggregated on the surface of bacteria,reaching the threshold of plasmon resonance between gold particles(Au NPs).Under the irradiation of near-infrared(NIR)light,the heat generated in situ killed bacteria.The subcutaneous abscess model experiment demonstrated that the temperature of the infected sites increased to a temperature enough to kill the bacteria(>50?)with the treatment of Pep-DA/Au under the irradiation of NIR light,while the temperature of the healthy tissue was not significantly increased(<45?).Pep-DA/Au photothermal treatment were able to avoid the damage to healthy tissue during traditional photothermal therapy(PTT).Moreover,Pep-DA/Au without antibiotics are not easy to induce bacterial resistance.These results provide a novel perspectives for precise treatment of bacterial infection.