Antibacterial mechanism of silver nanoparticles：a dose-dependent promotion of cell apoptosis / 中国组织工程研究

ABSTRACT

BACKGROUND:Silver nanoparticles (AgNPs) show strong antibacterial effect and are not easy to have drug resistance. But the antibacterial mechanisms of AgNPs have not been wel developed. OBJECTIVE:To explain the antibacterial mechanisms of AgNPs. METHODS:We investigated the influence of Ti, TiO2 and TiO2 containing AgNPs onEscherichia coliand Staphylococcus aureus by bacterial inhibition ring test. Escherichia coli was cultured in LB liquid medium with 0, 5, 10 mg/L AgNPs. We measured the absorbance value of bacterial culture. DNA gel electrophoresis was used to study the effect of AgNPs onEscherichia coliDNA. Then we researched the character of apoptosis on Escherichia coli by Annexin V and PI staining, using flow cytometry. RESULTS AND CONCLUSION:The inhibiting effect of Ti and TiO2 onEscherichia coliandStaphylococcus aureus was not obvious. But the inhibition rings of TiO2 containing AgNPs to bacteria appeared. The absorbance value of Escherichia coliculture was reduced whenEscherichia coliwas co-cultured with AgNPs. And this decrease tendency was in direct proportion with AgNPs concentration. AgNPs reduced the amount of DNA of Escherichia coli and this tendency was directly proportional with AgNPs concentration. TheEscherichia coli apoptosis rate induced by AgNPs was increased and this tendency was positively correlated to the AgNPs concentration. These results indicate that AgNPs can induce bacterial apoptosis to influence the growth of bacteria.