Antibacterial/Antifouling Functionalization Of Medical PVC

As one of the most widely used plastics in the field of medical devices,polyvinyl chloride(PVC)is often used to manufacture flexible medical products such as endotracheal tubes and urinary catheters.However,the hydrophobic surface which is easy to be contaminated by bacteria creates a restriction of polyvinyl chloride in clinical application.Once colonized by bacteria,a catheter-related infection seems unavoidable without a timely replacement of contaminated devices.Therefore,there is a great importance of antibacterial modification of polyvinyl chloride.In the thesis,the antibacterial modification of polyvinyl chloride was carried out by blending modification and surface modification,and the advantages and disadvantages were compared in the end of the thesis.In the first part,the antibacterial modification of polyvinyl chloride was carried out by blending with a newly synthesized gemini quaternary ammonium salt named QTHD.The antibacterial activity and thermal decomposition temperature of QTHD were tested out to satisfy the requirements for antibacterial modification.SEM images of brittle fracture interface,and mechanical properties indicated a general compatibility between QTHD with polyvinyl chloride.Contact antibacterial experiments and inhibition zone experiment proved that there is a strong antibacterial property of modified polyvinyl chloride.However,a substandard cytotoxicity of the modified polyvinyl chloride was tested out,which would limit its use.In the second part,in order to reduce the damage of antibacterial modification to the biocompatibility,a surface modification method was chosen to reduce the adhesion and kill adherent bacteria on the surface of polyvinyl chloride devices.An anionic polysaccharide,hyaluronic acid,was used to construct the antifouling bottom layer.Then a antibacterial agent,quaternized N,N-dimethylethylenediamine,was grafted onto the antifouling layer.Extracorporeal circulation antibacterial experiment(S.aureus)showed a 96%bacterial-adhesion reduction between polyvinyl chloride with antifouling polyvinyl chloride;while the reduction(95%)of the antibacterial/antifouling polyvinyl chloride was not much different from that of antifouling polyvinyl chloride.There are 43%of dead bacteria on the antibacterial/antifouling layer,while that proportion of antifouling layer was 23%.This proved an enhancement of the antibacterial ability of the antifouling layer.In the static anti-biofilm experiment,the antifouling/antibacterial polyvinyl chloride could effectively slow down the biofilm formation on the surface.This was of great significance for reducing catheter-related bacterial infections.Through the research in this thesis,the two methods,blending modification and antifouling/antibacterial surface modification,can both effectively enhance the antibacterial properties of medical polyvinyl chloride.We can flexibly choose the antibacterial functionalization method of polyvinyl chloride according to the safety requirements,processing methods and actual needs of the materials.