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Disinfection kinetics and mechanisms of silver nanoparticles-decorated silica hybrid composites against pathogenic microorganisms : 은나노입자 포함 실리카 Hybrid 복합체의 병원성 미생물 저감 효과 및 기전 연구

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Authors

박성준

Advisor
고광표
Major
보건대학원 보건학과
Issue Date
2016-08
Publisher
서울대학교 보건대학원
Keywords
silver nanoparticlemagnetic hybrid colloidsilica hybrid compositespathogenic microorganismdisinfectiondisinfection kineticsantimicrobial agent
Description
학위논문 (박사)-- 서울대학교 보건대학원 : 보건학과 환경보건학 전공, 2016. 8. 고광표.
Abstract
Silver nanoparticles (AgNPs) have been considered a powerful disinfectant for controlling various pathogenic microorganisms. At the same time, AgNPs may cause adverse effects on both human beings and our ecosystems due to their potential cytotoxicity and the difficulty of recovering them after release into the environment. In the present study, we characterized antimicrobial capabilities of using the novel micrometer-sized magnetic or non-magnetic silica hybrid composites decorated with monodispersed silver nanoparticles (AgNP-MHCs or AgNP-SiO2). These can prevent the possible aggregation of AgNPs through a seeding, coalescing or sorting-out, and growing strategy onto the outermost layer of silica composites, can enable long-term storage without the addition of stabilizer, and can be recovered easily using simple methods including magnetic collection, sedimentation or centrifugation in water system.
Firstly, we evaluated the antibacterial capabilities of AgNP-MHCs against target bacteria including L. pneumophila, B. subtilis, E. coli, and C. perfringens, and compared with the inactivation efficacy of AgNPs ~30 nm in diameter (nAg30). Among evaluated different composites of AgNP-MHCs, Ag30-MHCs and Ag30-MHC-Ls, which contained the largest size of AgNPs (~30 nm), showed the greatest antibacterial effects. After 1 h of exposure, more than 4-log10 reduction of L. pneumophila and 6-log10 reduction of B. subtilis was achieved by 4.6 × 10^9 particles/mL of Ag30-MHCs and of Ag30-MHC-Ls. In addition, Ag30-MHC-Ls maintained their strong antibacterial capabilities under anaerobic conditions.
Secondly, we elucidated the antiviral capabilities of Ag30-SiO2s against two model viruses, bacteriophage MS2 and murine norovirus (MNV), in each of the various water conditions. MNV was more susceptible to Ag30-SiO2s in all four water conditions (distilled, tap, surface, and ground water) compared to MS2. Furthermore, several water condition factors, including temperature and water-containing matter could affect the antimicrobial capabilities of Ag30-SiO2s. The modified Hom model (MHOM), representing either the shoulder at the beginning or the tail at the end, is the best-fit disinfection model for MNV disinfection. In addition, this study demonstrated that the effects of a certain level of non-chemically reacted obstacles in water are negligible in the usage of Ag30-SiO2s.
Finally, this study showed that Ag30-SiO2s can inhibit influenza A virus (IFV-A) effectively in a clear dose-dependent manner. However, when RT-PCR method was used to measure IFV-A inactivation, the efficacies were significantly underestimated because the major antiviral mechanisms of Ag30-SiO2s is the interaction with viral components located at the membrane. After 24 h of exposure to Ag30-SiO2, hemagglutinin (HA) and neuraminidase (NA) damage had occurred and the infection of IFV-A to MDCK (Madin-Darby Canine Kidney) cells had been reduced, measured by flow cytometry. The results showed that Ag30-SiO2s can cause non-specific damage of various IFV-A components.
In conclusion, Ag30-MHCs and Ag30-SiO2s can be considered excellent tools for controlling microbial pathogens under various environmental conditions with minimized release into the water environment. Moreover, Ag30-SiO2s can be synthesized using a high-yield, large-scale process that is cost-effective and able to meet large demands in water treatment. Furthermore, Ag30-SiO2 could inhibit various pathogenic microorganisms without significant resistances. Thus, improved usages of AgNPs in disinfection processes, can be achieved using our novel hybrid composites without significant harmful effects to human beings or our ecosystems.
Language
English
URI
https://hdl.handle.net/10371/120810
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