Antibacterial Coatings Prepared By Dopamine-assisted Deposition

Microbes,such as bacteria,usually survive in biofilm or planktonic states.In order to avoid the adverse effects of pathogens on human health,coating surface with zwitterionic materials can effectively prevent bacteria adhere onto the surface and the subsequent biofilm formation.Magnetic antibacterial materials can not only kill bacteria in planktonic state,but also can be collected and reused,which can prevent the leakage of antimicrobial agents and affective for environment.In this paper,two kinds of antimicrobial polymers,zwitterionic graft copolymer and polycation that are based on branched polyethylenimine?bPEI?,were designed and synthesized.the as-synthesized polymers were immobilized on the surface of substrates to form a zwitterionic coating and a sterilization coating,by dopamine-assisted deposition method,thereby obtaining bacteria adhesion-resistant material and magnetic sterilizing material.This method is facile and effective,and the antibacterial material prepared by this method has stable and high antibacterial property.The main work of this paper contains two parts as below.Firstly,zwitterionic graft copolymer bPEI-PSBMA was synthesized by graft polymerization on bPEI,and the bPEI-PSBMA_29%,bPEI-PSBMA_43%,bPEI-PSBMA_62%with different grafting rates were obtained by adjusting the ratio of the reactants.After one-step dopamine-assisted deposition,they were immobilized on the substrate to form zwitterionic coatings.The molecule structures and physical properties were investigated by FT-IR,¹H-NMR,¹³C-NMR,SEM,AFM,XPS and contact angle test,and the effects of bPEI-PSBMA with different grafting rates on the surface chemical properties of the coatings were studied.The results show that zwitterionic coatings were successfully immobilized on the substrate,and the density of zwitterionic unit on the coatings was increased with the grafting rates of polysulfobetaine in bPEI-PSBMA.It was proved by antibacterial testing and anti-protein test that such zwitterionic coatings had excellent resistance to E.coli and BSA adhesion.Secondly,two types of quaternary ammonium salt polymer,QbPEI-BC and QbPEI-C6 were synthesized by quaternization of benzyl chloride and chlorhexane with bPEI,respectively.After one-step dopamine-assisted deposition,recyclabe magnetic antibacterial materials,Fe₃O₄@PDA2.0-QbPEI-BC and Fe₃O₄@PDA2.0-QbPEI-C6were prepared by immobilized of such polymers on magnetic Fe₃O₄ nanoparticles.And another two magnetic antibacterial materials,Fe₃O₄@PDA1.0-QbPEI-C6 and Fe₃O₄@PDA0.5-QbPEI-C6 were obtained by changing the concentration of dopamine.The structures were characterized and the physical properties were investigated by FT-IR,TEM,TGA,XPS.It turns out that antibacterial coatings were successfully formed and coated on the magnetic Fe₃O₄ nanoparticles.And the surface of Fe₃O₄@PDA1.0-QbPEI-C6 was confirmed to contain a relatively large number of quaternary ammonium salt unit.The antibacterial test results show that all the as-synthesized magnetic antibacterial materials have excellent antibacterial properties,Fe₃O₄@PDA1.0-QbPEI-C6 has the highest antibacterial efficiency,and still maintain a high antibacterial rate after 10 times reused.The results of this study show that dopamine-assisted deposition is a facile method for preparing antibacterial coatings,which has the advantage of simplicity and efficiency,and the as-made antibacterial coatings are quite promising with stable performance and strong antibacterial ability.