Preparation And Application Of Antimicrobial Peptide Modified Fe₃O₄ Magnetic Mesoporous Silica Nanoparticles

Fe₃O₄ nanoparticles have attracted much attention in the field of biomedical materials due to their good biocompatibility.The surface of Fe₃O₄ nanoparticles is often functionalized to achieve practical application purposes.Polypeptides have received widespread attention due to their extensive and powerful antibacterial properties.However,currently,the preparation of antibacterial peptides is mainly faced with shortcomings such as poor stability,easy enzymatic hydrolysis,high synthesis costs,and high technical barriers required for the preparation and purification process,which are not suitable for large-scale industrial production.Therefor,one of the current reserch hotspots is how to prepare antibacterial peptides efficiently and environmentally friendly.In this thesis,mesoporous SiO₂ was constructed on the surface of Fe₃O₄ and antibacterial peptides were immobilized in the mesoporous channels based on Fe-S bonds to prepare efficient,durable,and recyclable antibacterial magnetic nanoparticles（Fe₃O₄@m SiO₂@Cys HHC10）.At the same time,this nanoparticle was used as an additive to modify high-temperature vulcanized silicone rubber,and its physical and antibacterial properties were studied.The specific results are as follows:（1）Preparation,characterization,and antibacterial properties of Fe₃O₄@m SiO₂@Cys HHC10.Magnetic nanoparticles（Fe₃O₄@m SiO₂）with a silica mesoporous structure on their surface were prepared by hydrothermal method,and then antibacterial polypeptides were fixed in the surface mesoporous channels of Fe₃O₄@m SiO₂ by forming Fe-S bonds.Magnetic nanoparticles（Fe₃O₄@m SiO₂Cys HHC10）were prepared,and their antibacterial properties against gram negative bacteria（Escherichia coli）and grampositive bacteria（Staphylococcus aureus）were systematically evaluated.The results showed that the magnetic nanoparticles had good antibacterial properties and biocompatibility against both Escherichia coli and Staphylococcus aureus,and after 10 cycles of recycling,their antibacterial rates against both Escherichia coli and Staphylococcus aureus remained above 70%.（2）The prepared antibacterial nanoparticles were used as additives to improve the mechanical and antibacterial properties of silicone rubber.The results showed that the elongation at break of silicone rubber increased by 3-4 times after adding Fe₃O₄@m SiO₂@Cys HHC10 nanoparticles,and the thermal stability of silicone rubber before and after modification remained unchanged.The modified silicone rubber also has significant antibacterial properties and biocompatibility.When exposed to Escherichia coli and Staphylococcus aureus for 6 hours,its antibacterial rate reached99.9%.In summary,this thesis has prepared highly effective,durable,recyclable,and biocompatible antibacterial magnetic nanoparticles,providing a new method for the preparation of new antibacterial agents.In addition,adding the prepared magnetic antibacterial nanoparticles as additives to silicone rubber can improve the mechanical properties of silicone rubber while maintaining good biocompatibility and increasing its antibacterial properties,providing a new strategy for the preparation of biomedical composite silicone rubber.