Construction Of Multifunctional Antibacterial Surface Of Implanted And Interventional Medical Equipment

Infection related to interventional and implanted medical devices is one of the common clinical complications.The main mechanism of bacterial infection is that bacteria adhere to the surface of medical devices and form biofilm.Systemic antibiotic administration may fail when infection occurs.Therefore,the prevention of bacterial adhesion and proliferation on the surface of materials is the key step to avoid infection.From the perspective of the application of medical devices,the materials need to have multiple functions to meet different clinical needs.For interventional devices,the materials need to resist the adhesion of proteins,platelets and blood cells to avoid thrombosis and pipeline blockage.For implant materials,good osteogenic activity and mechanical properties are crucial.Therefore,the ideal implant intervention and implanted materials need multifunctional antibacterial surface,which can be achieved by surface modification methods of materials science.In the first part of this thesis,the multifunctional antibacterial surface of blood contact catheter was studied.Polyurethane is a kind of commonly used medical catheter material.Hierarchical antifouling and bactericidal coatings are prepared on polyurethane(PU).The antibacterial surface(PU-DMH)consists of a hydrophilic polymer as the lower layer and antimicrobial peptideconjugated polymer brushes as the upper layer.The PU-DMH surface showed excellent broad-spectrum antibacterial activity.The amounts of adhered bacteria on pristine PU were?50 times higher than that of PU-DMH under flow condition.As the same time,PU-DMH has good blood compatibility and low cytotoxicity.Animal experiments also confirmed that PU-DMH can significantly reduce bacterial and cell adhesion.This work is expected to be used to prevent the infection of blood contact catheter.In the second part of this thesis,the multifunctional antibacterial surface of orthopedic implants was studied,and a stimulus responsive antibacterial osteogenic material was designed.Porous hydroxyapatite(HA)scaffolds were used as representative orthopedic implants.Through SI-ATRP and Schiff base reaction,osteogenic peptide GGGGGRGS(RGD)and antibiotic vancomycin(VAN)were coupled to polymer brushes to obtain multifunctional scaffolds with osteogenic,biocompatible and stimulus responsive antibacterial functions.RGD can promote the attachment and proliferation of osteoblasts.Vancomycin attached to the surface by Schiff base bond can achieve bacterial responsive release sterilization.In vitro antibacterial and cell culture experiments showed that the material had excellent five times repeated circulation antibacterial and biocompatibility.To sum up,this thesis studies the multifunctional antibacterial surface of medical devices,and successfully constructed polymer brushes with high antibacterial performance through surface initiated ATRP method.According to the specific needs of blood contact catheter,orthopedic implants and other medical devices,the polymer brushes was modified to achieve blood compatibility,osteogenesis and other functions,while improving the antibacterial performance to improve the therapeutic performance of medical devices.The research of this thesis provides a new strategy to solve the infection problem caused by medical devices,which has a certain academic significance and application prospects.