Comparison of TiO2 and ZnO nanoparticles for photocatalytic degradation of methylene blue and the correlated inactivation of gram-positive and gram-negative bacteria
Comparison of TiO2 and ZnO nanoparticles for photocatalytic degradation of methylene blue and the correlated inactivation of gram-positive and gram-negative bacteria
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DOI：
10.1007/s11051-013-1432-9
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发表时间：
2013-02-01
影响因子：
2.5
通讯作者：
Thompson, Ian P.
中科院分区：
文献类型：
--
作者：
Barnes, Robert J.;Molina, Rodrigo;Thompson, Ian P.
二氧化钛（TiO 2）和氧化锌（ZnO）纳米颗粒是重要的光催化剂，因此已被广泛研究用于从污染的空气和水中去除有机化合物以及用于微生物消毒。尽管对TiO 2和ZnO纳米颗粒对不同细菌物种的影响进行了大量研究，但仍不确定哪些细菌对这些化合物更敏感。很少有研究直接比较了ZnO和TiO 2在光照和黑暗条件下的毒性。此外，研究TiO 2和ZnO纳米颗粒对细菌的光催化灭活的作者未能研究纳米颗粒的活性氧（ROS）产生，使得难以将杀伤作用与ROS的产生相关联。在这项研究中，三种类型的金属纳米颗粒（ZnO < 50 nm，ZnO < 100 nm和TiO 2）已被表征，并通过亚甲基蓝（MB）的降解来评估ROS的产生。然后在四种代表性细菌上评估三种纳米颗粒浓度（0.01、0.1和1g/L）的光催化杀伤潜力：两种革兰氏阳性（S. aureus和B. subtilis）和2株革兰氏阴性（E.大肠杆菌和铜绿假单胞菌）。结果表明，在测试的三种纳米颗粒中，TiO 2纳米颗粒比ZnO纳米颗粒产生更多的ROS，对应于所检查的四种细菌中的三种的更大的光催化灭活。MB分解结果与细菌灭活结果良好相关，较高的TiO 2纳米颗粒浓度导致更大的ROS产生和细胞活力损失增加。虽然在紫外光下产生的ROS比TiO 2纳米颗粒少，但即使在黑暗条件下，ZnO纳米颗粒对两种细菌也是有毒的。在这项研究中，没有观察到细胞壁类型和细菌灭活之间的相关性的任何测试的纳米颗粒，虽然两个革兰氏阳性细菌是敏感的ROS生产。铜绿假单胞菌细胞对所有类型的处理都有抗性，并突出了这些纳米颗粒用于水处理的应用的潜在限制。
Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles are important photocatalysts and as such have been extensively studied for the removal of organic compounds from contaminated air and water and for microbial disinfection. Despite much research on the effect of TiO2 and ZnO nanoparticles on different bacterial species, uncertainties remain about which bacteria are more sensitive to these compounds. Very few studies have directly compared the toxicity of ZnO to TiO2 under both light and dark conditions. In addition, authors investigating the photocatalytic inactivation of TiO2 and ZnO nanoparticles on bacteria have failed to investigate the reactive oxygen species (ROS) generation of the nanoparticles, making it difficult to correlate killing action with the generation of ROS. In this study, three types of metal nanoparticle (ZnO < 50 nm, ZnO < 100 nm and TiO2) have been characterised and ROS production assessed through the degradation of methylene blue (MB). The photocatalytic killing potential of three nanoparticle concentrations (0.01, 0.1 and 1 g/L) was then assessed on four representative bacteria: two gram-positive (S. aureus and B. subtilis) and two gram-negative (E. coli and P. aeruginosa). Results showed that out of the three nanoparticles tested, the TiO2 nanoparticles generated more ROS than the ZnO nanoparticles, corresponding to a greater photocatalytic inactivation of three of the four species of bacteria examined. The MB decomposition results correlated well with the bacterial inactivation results with higher TiO2 nanoparticle concentrations leading to greater ROS production and increased loss of cell viability. Although producing less ROS than the TiO2 nanoparticles under ultraviolet light, the ZnO nanoparticles were toxic to two of the bacterial species even under dark conditions. In this study, no correlation between cell wall type and bacterial inactivation was observed for any of the nanoparticles tested although both gram-positive bacteria were sensitive to ROS production. P. aeruginosa cells were resistant to all types of treatment and highlight a potential limitation to the application of these nanoparticles for water treatment.