Research on Antibacterial Activity of Silver-Carried Oxidized Chitosan
In order to prepare a highly effective antibacterial agent,chitosan(CS)was used as raw material to prepare 6-carboxyl chitosan(C-COS)by laccase/2,2,6,6-tetramethylpiperidine-1-oxyl radical(TEMPO)system,and then the silver-carried oxidized chitosan(C-COS-Ag)was prepared by reaction with silver nitrate.The antibacterial activity of C-COS-Ag was studied.The results showed that the antibacterial effect of C-COS-Ag was significantly improved compared with CS.Its inhibitory zone diameters against Escherichia coli and Staphylococcus aureus were(22.75±1.50)and(13.75±2.50)mm,respectively,with a minimum inhibitory concentration of 6.10 μg·mL-1.The bacterial growth curve test confirmed that C-COS-Ag could significantly reduce the growth rate of Escherichia coli and Staphylococcus aureus;the penetration test of cell contents showed that C-COS-Ag could destroy the cell membrane and cell wall morphology of bacteria,resulting in the exudation of nucleic acids,proteins and other macromolecules,the increase of alkaline phosphatase activity,the decrease of β-galactosidase activity,the obstruction of galactose synthesis pathway,and the normal metabolism of bacteria were affected.Above results provided a theoretical basis for the application of C-COS-Ag.
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