Bactericidal Mechanisms Revealed for Rapid Water Disinfection by Superabsorbent Cryogels Decorated with Silver Nanoparticles

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• 作者：Siew-Leng Loo ; William B. Krantz ; Anthony G. Fane ; Yiben Gao ; Teik-Thye Lim ; Xiao Hu
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：February 17, 2015
• 年：2015
• 卷：49
• 期：4
• 页码：2310-2318
• 全文大小：534K
• ISSN：1520-5851

文摘

The authors have recently reported the fabrication of superabsorbent cryogels decorated with silver nanoparticles (PSA/AgNP cryogels) that demonstrate rapid water disinfection. This paper provides a systematic elucidation of the bactericidal mechanisms of AgNPs (silver nanoparticles), both generally and in the specific context of cryogels. Direct contact between the PSA/AgNP cryogel interface and the bacterial cells is required to accomplish disinfection. Specifically, the disinfection efficacy is closely correlated to the cell-bound Ag concentration, which constitutes >90% of the Ag released. Cells exposed to PSA/AgNP cryogels show a significant depletion of intracellular adenosine triphosphate (ATP) content and cell-membrane lesions. A positive ROS (reactive oxygen species) scavenging test confirms the involvement of ROS (路O₂^{鈥?/sup>, H₂O₂, and 路OH) in the bactericidal mechanism. Furthermore, exposed bacterial cells show an enhanced level of thiobarbituric acid reactive substances, indicating the occurrence of cell-membrane peroxidation mediated by ROS. In addition, this study reveals that both Ag+ and Ag0 are involved in the bactericidal mechanism of AgNPs via tests conducted using PSA cryogels with bound Ag+ ions (or PSA/Ag+ cryogels without reducing Ag+ to Ag0). Significantly, bacterial cells exposed to PSA/Ag+ cryogels did not show any cell-membrane damage even though the former had a higher cell-bound Ag concentration than that of the PSA/AgNP cryogels, thus indicating the differential action of Ag+ and Ag0.}