Construction And Properties Of Rosin-based Quaternary Ammonium Salt Dual-functional Antimicrobial Coating On Surface Of Silicone Rubber

Silicone elastomer(PDMS)is widely used in the field of implantable biomedical devices because of its flexibility,low toxicity and negligible induction of adverse biological responses.However,during the use of biomedical silicone rubber materials,direct contact with human tissue,bacteria can invade through a variety of ways,which is very easy to cause inflammation and infection.The construction of antimicrobial coating on the surface of biomedical silicone rubber can effectively inhibit the formation of biofilm and reduce the occurrence of this kind of inflammation and infection.Rosin is a mixture composed of a variety of resin acid isomers.The unique hydrogenated phenanthrene ring structure of rosin acid and the double bond and carboxyl functional groups which are easy to be chemically modified can provide a variety of reaction sites and have good reaction activity.The maleopimaric acid quaternary ammonium salt fungicide(MPA-N⁺)prepared from rosin by simple chemical modification not only shows efficient bactericidal properties,but also has no toxic side effects on normal human cells and has good biocompatibility.It has great potential to use it as a fungicide to develop antibacterial coating.In this paper,maleopimaric acid quaternary ammonium salt(MPA-N⁺)was used as bactericide and silicone rubber(PDMS)was used as biomedical implant substrate.MPA-N⁺was chemically grafted on the surface of silicone rubber material to construct the antibacterial coating of maleopimaric acid quaternary ammonium salt.In order to further improve the antifouling performance of the antibacterial coating,MPA-N⁺was combined with hydrophilic compounds such as amphoteric compounds,polyethylene glycol and vinyl pyrrolidone to construct dual-functional antibacterial coatings on the surface of silicone rubber materials by physical deposition and different chemical grafting methods.The antibacterial properties,antifouling properties,biocompatibility and anti-inflammatory properties of dual-functional antibacterial coatings were evaluated.The main contents and results are as follows:1.Construction and properties of rosin-based maleopimaric acid quaternary ammonium salt(MPA-N⁺)antimicrobial coatingRosin-based maleopimaric acid quaternary ammonium salt(MPA-N⁺)was used as a bactericide and was chemically grafted onto the surface of PDMS by amidation reaction to construct an antimicrobial coating.The antimicrobial coating expossess excellent antimicrobial activity against both Gram-positive bacterial(Staphylococcus aureus)and Gram-negative bacterial(Escherichia coli,Pseudomonas aeruginosa)strains with the colony index reduction values were 3.94,1.49,and 1.35,and the antimirobial activity could be maintained stably for 6days in PBS solution.Meanwhile,antimicrobial coating can effectively inhibit the formation of biofilms for 5 days.The biocompatibility of the coating was also evaluated,and the coating had no significant hemolysis for red blood cells and no toxic side effects for normal human cells,showing good biocompatibility.2.Construction and properties of dopamine-zwitterionic polymer-quaternary ammonium salt from rosin acid bifunctional antimicrobial coatingThe polymerizable rosin quaternary ammonium salt(GMA-MPA-N⁺)was used as the bactericide,the zwitterionic compound 2-methacryloxyethyl phosphorylcholine as the antifouling monomer,and dopamine was introduced to copolymerize the coating polymer,and the coating polymer was deposited on the surface of PDMS to construct the antimicrobial coating.The antimicrobial coating showed efficient bactericidal properties against Staphylococcus aureus,Escherichia coli and Pseudomonas aeruginosa,with bactericidal rates of 90.12%,92.02%and 88.41%,respectively.The antimicrobial coating can effectively inhibit the biofilm growth of pathogenic bacteria on the material surface for 5 days.The adhesion of bovine serum albumin,lysozyme and fibrinogen to the antimiceobial coating decreased by 84.88%,75.41%and 78.69%respectively,and the attachment of platelets to the coating surface decreased by 74.79%,so the coating has excellent antifouling properties.Meanwhile,the antimicrobial coating exhibited excellent biocompatibility,which induced no significant hemolysis and cytotoxicity toward mammalian cells.The anti-infection performance of the coating in vivo was determined by the mouse subcutaneous implant infection model experiment.The results exhibited that the coating still maintained efficient antimicrobial performance in mice and effectively inhibited the occurrence of inflammation.3.Construction and properties of polyethylene glycol-quaternary ammonium salt from rosin acid bifunctional antimicrobial coatingThe preparation of coating monomers by conjugating rosin acid-derived maleopimaric acid quaternary ammonium cation(MPA-N⁺)with different chain of lengths allyloxy polyethylene glycol(APEG).The monomers of the cation plus its linker conjugates(APEG_1200/2400-MPA-N⁺)were further grafted onto the surface of silicone rubber slides(PDMS)via plasma/UV-induced surface polymerization to form antimicrobial and antifouling coatings.The dual-functional coatings exhibited excellent antimicrobial activities against gram-negative and positive bacteria,with colony index falling values of 1.77,0.86 and 0.84,respectively.Meanwhile they effectively prevented biofilm formation.The coatings also greatly reduced protein adsorption and platelet adhesion,indicating their excellent antifouling capability.In addition,the APEG_1200/2400-MPA-N⁺cation coatings were biocompatible towards mammalian cells,as shown by in vitro cytotoxicity assays using rabbit erythrocytes and attached human aorta smooth muscle cells.In addition,the APEG₂₄₀₀-MPA-N⁺coating exhibited significant anti-infective activity in a rodent subcutaneous infection model.4.Construction and properties of polyvinylpyrrolidone-rosin-based quaternary ammonium salt bifunctional antimicrobial coatingThe dual-functional coating(antifouling and antimicrobial)was constructed though the combination of N-vinylpyrrolidone(NVP)and maleopimaric acid quaternary ammonium cation containing double bond functionality(GMA-MPA-N⁺)via surface-initiated reversible addition fragmentation chain-transfer(RAFT)polymerization.The presence of GMA-MPA-N⁺endowed the dual-functional coating with excellent broad-spectrum antimicrobial properties against Gram-positive bacterial(Staphylococcus aureus)and Gram-negative bacterial(Escherichia coli,Pseudomonas aeruginosa)strains,with colony index falling values of 1.35,1.29 and 1.02,respectively.The biofilm formation was inhibited on the dual-functional coating for up 21 days.Furthermore,the adhesion of protein and platelet on the dual-functional coating significantly decreased compared to the pristine substrates surface,and the cytotoxicity assays demonstrated that the coating displays excellent biocompatible towards mammalian cells.Most importantly,the subcutaneous implantation of samples in rats assay suggested that coating showed excellent anti-infective property in vivo.