Study On The Synthesis Of Zinc Oxide Nanoparticles Using The Fermentation Liquid Of Lactiplantibacillus Plantarum And Its Application In The Preparation Of Wound Repair Products

As the first barrier of the immune system,skin tissue plays a vital role in protecting organs from microbial infections and environmental changes.Once the skin is injured to form open wounds,which makes it extremely susceptible to the influence of the external environment.Once the wound becomes infected,the healing process is blocked,which may lead to serious complications.Therefore,in order to avoid serious infection,wound treatment is required.The composite dressing contained zinc oxide nanoparticles（ZnO NPs）combine antibacterial properties,biocompatibility,and the ability to promote wound healing,which could be considered for wound treatment as an ideal composite dressing.However,considering that the existing synthesis procedures of ZnO NPs often involve high-energy input and the use of toxic chemical reagents,exploring green synthesis methods is conducive to the development and application of ZnO NPs.This article used the fermentation liquid of Lactiplantibacillus plantarum to synthesize ZnO NPs,and explored its antibacterial mechanism,and the nanoparticles were used in the preparation of nanocomposite dressings,and the antibacterial properties,biocompatibility,and ability of the dressing to promote wound healing were evaluated in vivo and in vitro.The contents of each chapter are as follows:Chapter one:Review of the research progress of composite dressings containing nano-zinc oxide in wound healing.The formation and treatment strategies for chronic wounds,the application of ZnO NPs-containing composite dressings in wound healing,the synthesis and antibacterial activity of ZnO NPs were reviewed.Chapter two:To develop green,low-cost,and high-efficiency synthetic methods to promote their development in antibacterial applications.This study synthesized ZnO NPs using Lactiplantibacillus plantarum ZDY2013 fermentation liquid（LFL）combined with ultrasound-microwave assisted procedures,A variety of characterization methods were used to analyze the physical and chemical properties of ZnO NPs synthesized with the fermentation liquid（hereinafter abbreviated as LFL-ZnO）.The results show that LFL-ZnO has a spherical structure,the zeta potential is-25.533±0.205 mV,and the hydrodynamic size is 537.5 nm;LFL-ZnO has a hexagonal wurtzite structure with a crystallite size（41 nm）.In addition,antibacterial experiments proved that LFL-ZnO significantly inhibited the growth of methicillin-resistant Staphylococcus aureus at 100μg/mL concentration.This study verified that the possible antibacterial mechanisms of LFL-ZnO include destruction of bacterial cell integrity,generation of reactive oxygen species,and release of antibacterial Zn²⁺.Based on the above results,the synthetic method used in this study can synthesize ZnO NPs,and the synthesized LFL-ZnO perform antibacterial activity against methicillin-resistant Staphylococcus aureus.Chapter three:To copy with the complex wound environment,preparation of wound dressings with high flexibility,and mechanical strength would be needed.Therefore,this study prepared a kind of composite sponge using LFL-ZnO,polyvinyl alcohol（PVA）,and sodium alginate（SA）,through freeze-thaw cycle technology and freeze-drying molding,and characterization and performance analysis（swelling,moisture retention,degradability,mechanical properties）.It was found that the dressing was uniformly mixed with three materials,possessing mesoporous properties;the swelling rate of the composite sponge reached more than 840%,and still showed good mechanical properties after swelling;they could be degraded in Phosphate buffer saline solution,but not to cause immersion,and it could be used in the temperature range of 30～700℃ degradation rate reached 86.6%;the composite sponge possesses good flexibility not to break suffering the process of folded and unfolded.Therefore,the composite sponge prepared in this study has good application performance,Chapter four:In order to select an ideal wound dressing,it is crucial to establish animal models for in vivo evaluation.In this study,the antibacterial properties,biocompatibility,and the ability to repair full-thickness skin defects in SD rats were evaluated for the composite sponge dressings prepared by LFL-ZnO,polyvinyl alcohol and sodium alginate.It was found that the composite dressing containing LFL-ZnO showed a significant inhibitory effect on methicillin-resistant Staphylococcus aureus and Staphylococcus aureus;The biocompatibility test results show that the prepared composite sponges were non-hemolytic and did not affect cell proliferation（no cytotoxicity）.Based on the results of the above experiments,the composite sponge containing LFL-ZnO at a concentration of 1 mg/mL was selected for evaluation in vivo experiments.Evaluation of scalded wounds showed that the sponge dressing promotes wound healing;evaluation of infected wounds showed that it exerted an antibacterial effect,thereby promoting wound healing.Therefore,the composite dressings prepared in this study possess antibacterial activity against Staphylococcus aureus and biocompatibility,which can promote the reconstruction of bacterial-infected skin tissue.In conclusion,in this study,ZnO NPs could be synthesized by using Lactiplantibacillus plantarum fermentation liquid,and the composite sponge prepared fromLFL-ZnO,PVA and SA as materials perform antibacterial activity against Staphylococcus aureus,and could promote the skin of SD rats wound repair.The kind of composite dressing synthesized in this study possesses antibacterial and to be the ability to promote wound healing,which can provide a reference for the clinical treatment of scalded and infected wounds.