Biomimetic Mineralization Method To Prepare Composite Materials Of Chitosan And Zinc Oxide For Research On Antibacterial And Anti-microalgae

Biofouling is mainly caused by the colonization of microorganisms such as bacteria or microalgae on the surface of the substrate,which will bring huge economic losses to the marine industry.For this problem,the use of traditional materials is restricted because of their greater toxicity to non-target organisms in the environment.Therefore,the use of biodegradable,simple and economical materials to prevent the colonization of microorganisms,thereby preventing the formation of biofouling,is of great significance for the protection of substrates in the ocean.Chitosan(CS)is an important green and sustainable material with broad-spectrum antibacterial and film-forming properties.However,the film material prepared only by chitosan is prone to hydrolysis in an aqueous environment,is extremely unstable,and is difficult to exert its effect for a long time.Zinc oxide nanoparticles(ZnO NPs)have excellent properties such as anti-microbial and non-toxic.Applying ZnO NPs and their hybrids as nano-fillers to chitosan,the synergistic effect of the two is expected to develop more widely used materials.In this article,we prepared ZnO NPs by wet chemical methods under mild conditions and simple operations,and verified their inhibitory effects on E.coli and S.aureus.The minimum inhibitory concentration(MIC)was 0.250 mg/mL and 0.500 mg/mL,and the minimum bactericidal concentration(MBC)was 1.000 mg/mL.On this basis,we use a biomineralization process to combine wet chemical methods and coagulation bath methods to induce the in-situ generation of ZnO NPs in the chitosan macromolecules to obtain organic-inorganic hybrid CS@ZnO composite films.And explored its physical and chemical properties,antibacterial and anti-microalgae properties.Experiments show that,compared with chitosan film(CS film),the water solubility of CS@ZnO composite film is significantly improved,and the tensile strength of the composite film can be increased by 90%,and the elongation at break can be increased by 42%.CS@ZnO composite film has inhibitory effects on the growth of E.coli and S.aureus.The CS@ZnO composite film was co-cultured with Microcystis aeruginosa(M.aeruginosa)and Chlorella pyrenoidosa(C.pyrenoidosa)for 15 days.The inhibition rate of algae growth can reach 63.46%and 56.95%respectively.Therefore,this green and clean organic-inorganic hybrid composite membrane will hopefully be applied to the surface of other materials to effectively solve the problem of biofouling caused by microbial colonization.