Antibacterial Mechanism Of ZnO/Cinnamaldehyde/Tea Polyphenol-polylactic Acid Coaxial Nanofiber Films Against Shewanella Putrefaction

In this paper,the CMA/TP-PLA coaxial nanofiber films were preparedwith polylactic acid(PLA)as the shell materials,cinnamaldehyde(CMA)and tea polyphenol(TP)as core materials by coaxial electrostatic spinning method.And then the CMA/TP-PLA coaxial nanofiber films were modified by in-situ synthesis of nano-ZnO and the ZnO/CMA/TP-PLA coaxial nanofiber films were prepared.Meanwhile,the microstructure of the films were characterized by SEM,XRD and FT-IR,and their physicochemical properties were measured such as thermal stability,hydrophobicity,mechanical properties,and water vapor transmission rate etc.In addition,the dominant spoilage bacterium of aquatic products,Shewanella putrefaciens was used as the antibacterial object to reveal the antibacterial properties and mechanism of CMA/TP-PLA and ZnO/CMA/TP-PLA coaxial nanofiber films.1.The microstructure and physicochemical properties of CMA/TP-PLA coaxial nanofiber films were studied.The results show that CMA and TP are wrapped in PLA nanofiber films with physical mixing mode.Compared with coreless PLA nanofibers,the diameter of PLA coaxial nanofibers is reduced and the distribution is concentrated after add the core materials.And the diameter distribution of CMA/TP-PLA coaxial nanofibers with the composite core materials is the most concentrated.The addition of the core material is helpful to improve the physicochemical properties of the films.The CMA/TP-PLA coaxial nanofiber film has the best mechanical properties,good thermal stability,and the best hydrophobicity and water vapor transmission rate.2.Using as S.putrefaciens as the object,the antibacterial properties and mechanism of CMA/TP-PLA coaxial nanofiber films were studied.The results show that the TP with hydrophilic group in the CMA/TP-PLA coaxial nanofiber films was preferentially released to exert its antibacterial effect,and the CMA released later assisted the TP to act on the S.putrefaciens together,which caused the cell membrane structure of S.putrefaciens are more severely damaged,many holes appear on the surface of the cells,and a large amount of intracellular matrix is leaked,resulting in the death of the bacteria.3.The effect of the amount of ZnO sol on the morphologies and physicophysicochemical properties of ZnO/CMA/TP-PLA coaxial nanofiber films were studied.The results show that the diameter of 1.0% ZnO/CMA/TP-PLA coaxial nanofibers is smaller and they are continuous and uniform.The addition of ZnO sol may cause coupling between molecules or the existence of hydrogen bonding forces in the ZnO/CMA/TP-PLA coaxial nanofiber films,thereby affecting the thermal stability,hydrophobicity,mechanical properties and water vapor transmission rate of the films.Among them,the performance of 1.0%ZnO/CMA/TP-PLA coaxial nanofiber film is the optimal.4.Using S.putrefaciens as the object,to reveal the antibacterial properties and mechanism of ZnO/CMA/TP-PLA coaxial nanofiber films were researched.The results show that the antibacterial properties of 1.0% ZnO/CMA/TP-PLA coaxial nanofiber films are optimal.Moreover,the slow-release CMA and TP from the coaxial nanofiber films are interact with the nano-ZnO in the shell,make the permeability of the S.putrefaciens cell membrane increase,enhance the destroy ability to the integrity of the membrane,make a large amount of make intracellular matrix accumulate and leak.And it interferes with the protein expression of the bacterial cells,degrades the large molecular proteins,thereby inhibiting the growth and metabolism of the microorganisms,and eventually leading to bacterial death.