Preparation And Evaluation Of Biocompatible,Antibacterial Composite Coatings On PTFE Implants

Polytetrafluoroethylene（PTFE）has good mechanical properties,chemical stability and bio-inertness,and does not cause the body’s rejection.However,as one of the main materials in rhinoplasty prosthesis and artificial blood vessels,the low surface energy and poor hydrophilicity makes it difficult to interact with cells.That needs to be improved.However,conventional methods usually showed disadvantages of complicated procedures and rather large damage to the substrate,owing to the stability of PTFE.Therefore,a simple and effective modification method becomes one of the research hotspot in this area.In this paper,a composite film of polydopamine and TiO₂（PDA/TiO₂）was designed and prepared on PTFE,on the basis of the excellent adhesive ability of PDA and biocompatibility of TiO₂.Also,triclosan（TCS）was added to form a PDA/TCS/TiO₂ composite film to further impart the film with long-lasting antibacterial properties.The main results of this paper are as follows:（1）Preparation and evaluation of PDA/TiO₂ composite film on PTFEA preparation method was developed to prepare PDA/TiO₂ composite films on PTFE:the surface was first treated by plasma and then used for in-situ co-deposition of PDA/TiO₂.The prepared composite film is completely continuous,and the content of TiO₂ in the composite film can be controlled by the content of TiO₂ hydrosol added during co-deposition.The bond between the composite film and the substrate was very strong,and the shear strength reached 23.5 MPa.The composite film greatly improved the hydrophilicity and cell compatibility of the PTFE substrate,the water contact angle decreased from 118°to about 50°and the adhesion and proliferation of NIH3T3 and MC3T3-E1 cell were better than those of bare PTFE.（2）Preparation and evaluation of PDA/TCS/TiO₂ composite film on PTFEBased on the preparation method of PDA/TiO₂ composite film,TCS was successfully introduced to be PDA/TCS/TiO₂ composite films.The content of TCS could be controlled through the volume ratio of the triclosan-ethanol solution and the TiO₂hydrosol.The introduction of TCS showed few effects on surface morphology,crystalline phase and surface hydrophilicity of the composite films.The bonding strength of the composite films increased with the increasing TCS content.With a proper content of TCS,the shear strength reached 29.4 MPa.The cytocompatibility of PDA/TCS/TiO₂ composite film was also affected by TCS content.A high TCS content showed obvious detrimental effects on cell compatibility;while a low TCS content showed comparable cell compatibility in comparison with bare PTFE.PDA/TCS/TiO₂ composite films had good inhibitory effect on Staphylococcus aureus and Escherichia coli,and such property lasted long time.The composite film still showed antibacterial effect after being immersed in PBS buffer for 14 days.The release curve of PDA/TCS/TiO₂ composite film showed that the release of TCS in the early stage was faster and the speed was taped off then.After 14 days of release,the residual amount of TCS in the composite film was about 10%.And there would be basically no TCS residue after 21 days in PBS buffer.