Research On The Preparation Of Perfluoropolyether Coating Of Silicone Surface And Its Antibacterial And Anti-adhesive Performance

Implantable medical devices such as urinary catheters are indispensable tools in modern medicine for urinary retention and urinary incontinence.However,they provide a place for bacterial invasion and proliferation after implantation,with a high probability of causing the risk of associated urinary tract infections,which greatly threatens the health and even the life of patients.Currently,most commercial catheters are nano-silver coated catheters,which have good antibacterial effects on Gram-positive and Gram-negative strains.However,due to complex internal environment,implantable catheters inevitably adsorb substances such as proteins and polypeptides.What’s more,pure nano-silver coated catheters have no anti-adhesion performance,which greatly affects the antibacterial effect of nano-silver coatings.Perfluoropolyether(PFPE)can form an inert amphiphobic coating on the surface of materials after functionalization due to its low surface energy,which can effectively prevent bacterial adhesion.In this study,nano-silver was used as antibacterial agent and PFPE was used as low surface energy modifier to modify silicone rubber.The method comprises the following steps:Firstly,a layer of polydopamine was deposited on the surface of silicone rubber using the strong adhesion of dopamine,and active groups such as amino group and phenolic hydroxyl group are introduced on the surface.Subsequently,the nano-silver coating was deposited by in-situ formation method,and then the remaining active groups reacted with 2-bromoisobutyryl bromide to form the active center on the surface of atom transfer radical polymerization(ATRP),which led to the surface grafting polymerization of perfluoropolyether methacrylate(PFPE-MAA),thus forming the hydrophobic coating(SR-F-Ag)on the silicone surface to make it resistant to bacterial adhesion.The maximum contact angle of the coating was 139°.After 1 h of interaction with bacteria,the antibacterial rate of E.coli and S.aureus at the concentration of 10~6CFU/m L could reach more than 99%.The results of anti-bacterial adhesion test showed that the anti-adhesion rate of SR-F-Ag coating remained above 90%after 48h interaction with bacterial solution,and the anti-adhesion rate started to decrease to below 90%after 72 h.Secondly,perfluoropolyether mercaptan(PFPE-SH)was used as a low surface energy modifier to perform hydrophobic modification on silver nanoparticles to obtain perfluoropolyether modified silver nanoparticles(F-AgNPs),which were then dispersed into a mixed solution consisting of double bonded silicone oil,hydrogen hardener and tetrahydrofuran.The modified coating(SR-F-AgNPs)was obtained by dipping the silica gel sheet into the above solution and curing at 100℃for 6 h.The contact angle of SR-F-AgNPs was up to 135°.After 1 h of interaction with bacteria,the antibacterial rate of 10~6 CFU/m L E.coli and S.aureus reached more than 99%.The antibacterial adhesion test results showed that the anti-adhesion rate of SR-F-AgNPs coating was more than 90%after 48 h of interaction with bacteria,and after 72 h,the anti-adhesion rate decreased to less than 90%.Thirdly,perfluorinated polyether allyl ether(PFPE-allyl)was prepared by Williamson-ether formation reaction.PFPE-allyl was used as a hydrophobic modifier to replace double-bond silicone oil,and was mixed with hydrogen-containing curing agent and oil-soluble silver nanoparticles to form a silicone curing system.The silicone film(F-SR-Ag)containing PFPE and nano silver was obtained by curing at 100℃for6 h.As a co-crosslinked monomer,the resulting films were more stable,but the contact angle was slightly lower,reaching the highest at 10%PFPE content(122°).Its antibacterial effect was similar to that of the above materials,and the antibacterial effect on 10~6 CFU/m L E.coli and S.aureus was more than 99%after treated for 1 h.