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Preparation, characterization and antibacterial mechanism of the chitosan coatings modified by Ag/ ZnO microspheres
Author(s) -
Wei Xuqing,
Li Qiuying,
Wu Chaoling,
Sun Tong,
Li Xuepeng
Publication year - 2020
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.10605
Subject(s) - scanning electron microscope , coating , materials science , chitosan , membrane , chemical engineering , shewanella putrefaciens , composite number , zinc , fourier transform infrared spectroscopy , nuclear chemistry , antibacterial activity , chemistry , nanotechnology , bacteria , composite material , metallurgy , biochemistry , biology , engineering , genetics
BACKGROUND To improve the physicochemical and antibacterial properties of coatings, the chitosan (CS) coatings were respectively prepared by a casting method with zinc oxide (ZnO) and silver (Ag)/ZnO microspheres as modifiers. The chemical structures and micromorphology of ZnO, Ag/ZnO microspheres and CS coatings were characterized by X‐ray diffraction, Fourier‐transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive X‐ray spectroscopy. Furthermore, using the dominant spoilage bacteria of aquatic products, Shewanella putrefaciens and Pseudomonas aeruginosa , as objects, the antibacterial activities and mechanism of the CS coatings were investigated. RESULTS The results show that ZnO and Ag/ZnO microspheres are dispersed homogeneously in the CS coatings. After modified by ZnO and Ag/ZnO microspheres, the mechanical properties and antibacterial abilities of the CS coatings are improved, and that of 0.5% Ag/ZnO‐CS coating is the optimal. For pure CS coating, the bacterial cell membrane is damaged slightly because of the electrostatic interaction between NH 3+ of CS and the negative charge on bacterial surface. After treated by ZnO–CS composite coating, the bacterial cell membrane is destroyed badly on account of the earlier‐mentioned ion interaction and disturbing the synthesis of high molecular weight total protein. CONCLUSION With regard to Ag/ZnO–CS composite coating, the bacterial cell membrane is damaged seriously and cell contents are completely released due to ion interaction, disturbing the synthesis of high molecular weight total protein and low molecular weight membrane protein. Hence, Ag/ZnO–CS composite coatings are antimicrobial materials and food preservative materials with great potential application. © 2020 Society of Chemical Industry