Construction Of Antibacterials Based On ZIF-8 And Its Inhibition Of Microbial Influenced Corrosion

Corrosion is a main cause to ruin a large number of equipment which is made of metal materials.There are many kinds of corrosion such as chemical corrosion,electrochemical corrosion and microbial influenced corrosion.The corrosion caused by microorganism can damage the material itself,and it also destroys the anticorrosive coatings.In order to reduce the economic losses caused by the microbial influenced corrosion,it is necessary to restrain the corrosion.At present,many studies have found that the corrosion of the material by plankton could be ignored.The biofilm generated by the microorganisms is the main reason to aggravate the corrosion.Under the protection of the biofilm,bacteria colonize stubbornly on the metal which accelerate the corrosion of the metal surface.ZIF-8 is a class of porous metal-organic framework formed by the self-assembly of Zn²⁺and 2-methylimidazole(2-Me Im).Owing to its large specific surface and good stability,its surface can be modified easily.Silver nanoparticles(AgNPs)have nano effect and can easily enter the microorganisms to produce reactive oxygen species(ROS),thus blocking the growth and metabolism of microorganisms.D-cysteine(D-cys)can change the permeability of biofilm so that the microbes can stay afloat without clumping.Based on these,three kinds of nano-antibacterial materials were designed and synthesized in this paper,namely ZIF-8,ZIF-8@Ag and ZIF-8@Ag/D-cys.As a carrier,ZIF-8 not only solved the problem of easy aggregation of AgNPs and low antimicrobial activity,but also obtained a better synergistic antimicrobial effect.In order to further improve the inhibition activity of antibacterial materials on biofilm,D-cys was modified on AgNPs surface.This work is divided into the following two parts:In the first part,ZIF-8 nanoparticles were designed and synthesized on the basis of literature investigation.Then,AgNPs were reduced in situ on the surface of ZIF-8 to form ZIF-8@AgNPs nanomaterials.The ZIF-8@Ag/D-cys nanocomposite was obtained by modifying D-cys on AgNPS with impregnation method.Through transmission electron microscopy(TEM)and scanning electron microscopy(SEM)characterization,it was found that the average diameters of ZIF-8@Ag/D-cys nanocomposites were about370 nm.The antimicrobial activity of ZIF-8@Ag/D-cys was tested by disk agar diffusion method(DAD)and minimum inhibitory concentration(MIC).The inhibitory area of ZIF-8@Ag/D-cys against E.coli was 482.80 mm~2,and the minimum inhibitory concentration was 15.6 ppm.The inhibition area of S.m was 639.21 mm~2,and the minimum inhibitory concentration was 3.9 ppm.Compared with ZIF-8 and ZIF-8@Ag,the experimental results proved that the maximum inhibitory region and the minimum inhibitory concentration were obtained under the same conditions.Therefore,ZIF-8@Ag/D-cys has excellent antibacterial properties.In the second part,ZIF-8@Ag/D-cys antibacterial material was uniformly coated on the surface of X70 carbon steel and Ti-Ni alloy.The effects of different coating contents on the microbe corrosion resistance of X70 carbon steel and Ti-Ni alloy were tested by electrochemical method under the same condition.The surface of the alloy was observed by scanning electron microscopy(SEM).The surface of X70 carbon steel and Ti-Ni alloy were tested by FM and CLSM.The results showed that ZIF-8@Ag/D-cys coating could effectively remove the biofilms of E.coli and S.m,thus reducing the agglomeration of microorganisms on the alloy surface.The corrosion of the alloy in different environments was measured by electrochemistry.The results showed that the microorganism could accelerate the corrosion of the alloy in artificial medium.However,the coating ZIF-8@Ag/D-cys was effective to reduce the corrosion of alloy.Therefore,the ZIF-8@Ag/D-cys coating prepared could effectively inhibit microbial corrosion.To sum up,ZIF-8@Ag/D-cys composite successfully designed in this paper has the dual functions of high antibacterial and corrosion resistance,which is expected to provide a new way for microbial corrosion protection.