Anti-infection Functionalization Of Implantable And Interventinal Medical Device Surface Based On Polyaldehyde Polymer

With the progress of bioengineering technology,implantable and interventional medical devices have gained widespread usage in medical and plastic fields.However,the incidence of medical device-related infections has also risen,as medical devices are prone to bacterial adherence on their surfaces,leading to the formation of biofilm.Functional antibacterial surfaces for implantable medical devices can endow these materials with various functions,such as anti-infection and promotion of postoperative recovery while maintaining their original value,thus enhancing their practicality in clinical environments.Polyaldehyde-based polymers,possessing numerous reactive sites,play a pivotal role in constructing antimicrobial functionalized surfaces.This thesis focuses on silicone rubber catheter and hydroxyapatite,representing short-term interventional and long-term implantable materials,respectively.The polyaldehyde-based polymer oxidized PHEMA is grafted onto the material surface using the surfaces modification method.Antibiotics are loaded onto the implantable materials via the Schiff base reaction,endowing them with adaptive anti-infection properties.Additionally,the materials are modified to possess anti-fouling and bone-promoting functions in response to clinical environment requirements,achieving surface antibacterial functionalization.Firstly,this thesis addresses the problem of infection in a typical short-term interventional device,silicone rubber(SR)urinary catheters with small diameter.To tackle this issue,a uniform hydroxyethyl methacrylate(HEMA)hydrogel coating was applied to the inner and outer walls of the catheter using the "hydrogel skin" method.An antibiotic ceftazidime was loaded by Schiff base reaction,and the outer surface was coated with xanthan gum to improve lubricity.Based on the experimental results,the modified material exhibits excellent hydrophilicity,along with a remarkable 96.1% reduction in surface friction compared to the original silicone rubber catheter.The antibacterial efficacy against E.coli and S.aureus exceeded 99.99%.Moreover,the coating demonstrated superior stain resistance,which effectively prevented bacterial biofilm formation on the catheter surface for two days and suppressed catheter encrustation.In addition,the experimental results demonstrated that the modified catheter has good biocompatibility and showed excellent antiinfection performance in vitro.This thesis aims to provide a general strategy for surface modification of small diameter medical catheters,enabling them to have internal and external antibacterial functions.Secondly,this thesis focuses on addressing post-implantation infection of porous hydroxyapatite,a long-term orthopedic implant material.The surface of the material was modified by grafting oxide PHEMA polymer brushes using the surface-initiated atom transfer radical polymerization(SI-ATRP)method,and Vancomycin(VAN)was loaded through a Schiff base reaction.Pro-osteogenic peptide RGD was also loaded through a C-N bond,endowing the material with antimicrobial responsiveness and osteogenic activity.Experimental results have demonstrated that the modified material possesses long-lasting antibacterial properties and could prevent bone defects in the long term.In addition,since hydroxyapatite is derived from natural bovine bone and its porosity cannot be precisely controlled,the conditions for surface modification can be significantly affected.Thus,this study examined the optimal reaction conditions for ATRP under various porosity conditions and investigated the removal conditions of toxic catalysts after the reaction,further improving the biosafety of the modified implant material.The findings of this study are expected to offer valuable insight into ATRP surface modification of natural porous materials.In summary,two representative implantable and interventional medical devices,SR urinary catheter and hydroxyapatite,were selected to modify the surface antibacterial functionalization with polyaldehyde polymers.In order to meet the clinical needs,in addition to the responsive antibacterial characteristics,the functional coatings with anti-fouling,lubrication and bone-promoting properties were further constructed.It provides a new idea for the internal modification of small diameter catheter and the surface coating design of natural porous implantable materials.