The Construction And Application Of Antimicrobial Materials Based On Ginger-derived Extracellular Vesicles For Anti-infection Therapy

The global community is currently facing a health crisis triggered by antibiotic resistance.The high costs and lengthy periods associated with new drug development exacerbate the challenges in research and development.The complex environment of infections within the body poses a significant threat to the effectiveness of existing antimicrobial drugs.There is an urgent need to develop new antimicrobial materials and strategies to effectively tackle bacterial infections.Extracellular vesicles（EVs）,owing to their excellent biocompatibility,stability in blood circulation,and targeting capabilities,have emerged as one of the ideal delivery systems.Plant-derived EVs,in particular,have garnered widespread attention due to their low immunogenic risk and the possibility of sustainable mass production.Therefore,this thesis focuses on the development of novel antimicrobial composite materials by combining plant-derived EVs with nanoparticles to achieve electrodynamic therapy（EDT）and synergistic antibacterial effects with antibiotics for the treatment of complex internal infections.This combination strategy not only extends the circulation time of antimicrobial materials or antibiotics in the blood,enhancing their accumulation at the site of infection and thus improving utilization but also enhances the interaction between antimicrobial materials and bacteria,increasing the effective concentration of antimicrobial materials inside bacteria.This not only improves the bactericidal efficiency of the antimicrobial materials but also helps to restore the sensitivity of existing antibiotics,ultimately achieving efficient treatment of infections caused by pathogenic and antibiotic-resistant bacteria.The detailed research content are as follows:In chapter two,in pursuit of understanding the interactions between various plant-derived EVs and bacteria,the aim is to construct novel antibacterial composite materials that enhance the bactericidal efficiency of nanoparticles.Different plant-derived EVs were obtained through ultracentrifugation.Their safety and bacterial internalization efficiency were evaluated,revealing that ginger-derived EVs exhibited the best performance.Further investigation into the mechanism behind the strong internalization capability of ginger-derived EVs suggests a link to their lipid composition.This discovery not only reveals the strong internalization ability of ginger-derived EVs in interacting with bacteria but also provides a preliminary explanation of the key role lipids play in this process.These research findings have enhanced our understanding of the interactions between plant-derived EVs and bacteria,laying a solid foundation for the subsequent development of novel antibacterial composite materials.In chapter three,to address the issue of insufficient dynamic treatment strategies due to the unique hypoxic microenvironment of in vivo infections,a biomimetic nanoplatform（EV-Pd-Pt）was constructed by combining ginger-derived EVs with EDT,which does not rely on oxygen.This platform achieves safe and efficient treatment of hypoxic in vivo infections.Using subcutaneous abscesses with low oxygen and H₂O₂ levels as the infection model,the inherent photothermal and electrodynamic properties of Pd-Pt nanosheets allowed the EV-Pd-Pt nanoparticles to exhibit a synergistic antimicrobial effect both in vitro and in vivo.The ingenious integration of ginger-derived EVs extended the blood circulation time of Pd-Pt,enhancing its accumulation at the subcutaneous infection site.Furthermore,EV-Pd-Pt entered the bacteria in a lipid-dependent manner,increasing the accumulation of nanoparticles inside the bacteria,thereby achieving safe and efficient treatment in complex hypoxic infection environments.In chapter four,to address the challenges of bacterial resistance and the difficulty of antibiotic penetration through the blood-brain barrier（BBB）caused by multidrug-resistant bacteria in encephalitis,a self-delivering nanomedicine,AMK@ZIF-EVs,was constructed using ginger-derived EVs and antibiotic-based metal-organic framework.This nanomedicine enhances the permeability across the BBB and restores the sensitivity of multidrug-resistant bacteria to antibiotics,achieving effective treatment of encephalitis caused by such bacteria.Leveraging the high uptake and prolonged circulation characteristics of EVs,this self-delivering nanomedicine can effectively traverse the BBB and accumulate at lesion sites.The lipid-dependent uptake mechanism of EVs increases bacterial uptake of AMK@ZIF-EVs.Within the bacterial cell,adenosine triphosphate disassociates the AMK@ZIF-EVs,releasing Zn²⁺and amikacin（AMK）.The liberated Zn²⁺effectively inhibits the hydrolysis of AMK,thereby enhancing the antibiotics intracellular efficacy.The combined action of these elements results in a highly effective eradication of antibiotic-resistant bacteria.Furthermore,in vivo distribution studies have shown that this intravenously injected self-delivering nanomedicine accumulates effectively at infection sites and exhibits significant therapeutic effects against encephalitis caused by multidrug-resistant Acinetobacter baumannii（MDR-AB）.In summary,this thesis addresses the global challenge of pathogenic bacterial infections,particularly the issue of antibiotic-resistant bacterial infections,through a series of innovative research initiatives.It proposes a novel solution:a strategy that combines plant-derived EVs with nanoparticles.Through a series of experiments,this approach has been proven to effectively prolong the circulation time of nanoparticles in the bloodstream,enhance the interaction between nanoparticles and bacteria,and improve the efficiency of drug delivery into cells.Initially,an extensive analysis and screening of the interactions between various plant-derived EVs and bacteria were conducted.The results showed that ginger-derived EVs could be effectively internalized by bacteria.Furthermore,when combined with Pd-Pt nanosheets,these EVs can form an efficient nanocomplex,significantly enhancing antimicrobial effects.Lastly,this research also combined ginger-derived EVs with antibiotic-based metal-organic framework nanoparticles,achieving antibiotic penetration through the BBB and restoring antibiotic sensitivity to resistant bacteria.These findings offer new therapeutic strategies for addressing antibiotic resistance and deep-seated infections within the body.