Department of Environmental Health, College of Public Health, East Tennessee State University, Johnson City, TN 37614, USA.
Sci Total Environ. 2012 Jun 1;426:414-22. doi: 10.1016/j.scitotenv.2012.03.049. Epub 2012 Apr 20.
Current understanding of potential toxicity of engineered nanomaterials to aquatic microorganisms is limited for risk assessment and management. Here we evaluate if the MetPLATE™ test can be used as an effective and rapid screening tool to test for potential aquatic toxicity of various metal-based nanoparticles (NPs). The MetPLATE bioassay is a heavy metal sensitive test based on β-galactosidase activity in Escherichia coli. Five different types of metal-based NPs were screened for toxicity: (1) citrate coated nAg (Citrate-nanosilver), (2) polyvinylpyrrolidone coated nAg (PVP-nAg), (3) uncoated nZnO, (4) uncoated nTiO(2) and (5) 1-Octadecylamine coated CdSe Quantum Dots (CdSe QDs); and compared with their corresponding ionic salt toxicity. Citrate-nAg was further fractionated into clean Citrate-nAg, unclean Citrate-nAg and permeate using a tangential flow filtration (TFF) system to eliminate residual ions and impurities from the stock Citrate-nAg suspension and also to differentiate between ionic- versus nano-specific toxicity. Our results showed that nAg, nZnO and CdSe QDs were less toxic than their corresponding ionic salts tested, while nano- or ionic form of TiO(2) was not toxic as high as 2.5 g L(-1) to the MetPLATE™ bacteria. Although coating-dependent toxicity was noticeable between two types of Ag NPs evaluated, particle size and surface charge were not adequate to explain the observed toxicity; hence, the toxicity appeared to be material-specific. Overall, the toxicity followed the trend: CdCl(2)>AgNO(3)>PVP-nAg>unclean Citrate-nAg>clean Citrate-nAg>ZnSO(4)>nZnO>CdSe QDs>nTiO(2)/TiO(2). These results indicate that an evaluation of β-galactosidase inhibition in MetPLATE™ E. coli can be an important consideration for rapid screening of metal-based NP toxicity, and should facilitate ecological risk assessment of these emerging contaminants.
目前，对于水生微生物而言，工程纳米材料潜在毒性的理解仅限于风险评估和管理。在这里，我们评估 MetPLATE™ 测试是否可作为一种有效且快速的筛选工具，用于测试各种基于金属的纳米颗粒（NPs）的潜在水生毒性。MetPLATE 生物测定是一种基于大肠杆菌β-半乳糖苷酶活性的重金属敏感测试。五种不同类型的基于金属的 NPs 被筛选出毒性：（1）柠檬酸包覆的 nAg（Citrate-nanosilver），（2）聚乙烯吡咯烷酮包覆的 nAg（PVP-nAg），（3）未包覆的 nZnO，（4）未包覆的 nTiO(2)和（5）1-十八胺包覆的 CdSe 量子点（CdSe QDs）；并将其与相应的离子盐毒性进行比较。进一步使用切向流过滤（TFF）系统将柠檬酸包覆的 nAg 分为清洁柠檬酸包覆的 nAg、不清洁柠檬酸包覆的 nAg 和渗透物，以从储备柠檬酸包覆的 nAg 悬浮液中消除残留离子和杂质，并区分离子与纳米特异性毒性。我们的结果表明，nAg、nZnO 和 CdSe QDs 的毒性低于测试的相应离子盐，而 TiO(2)的纳米或离子形式的毒性高达 2.5 g L(-1)，对 MetPLATE™ 细菌没有毒性。尽管评估的两种 Ag NPs 之间存在依赖于涂层的毒性，但粒径和表面电荷不足以解释观察到的毒性；因此，毒性似乎是材料特异性的。总体而言，毒性遵循以下趋势：CdCl(2) > AgNO(3) > PVP-nAg > 不清洁的柠檬酸包覆的 nAg > 清洁的柠檬酸包覆的 nAg > ZnSO(4) > nZnO > CdSe QDs > nTiO(2)/TiO(2)。这些结果表明，MetPLATE™ 大肠杆菌中β-半乳糖苷酶抑制的评估可以成为快速筛选基于金属的 NP 毒性的重要考虑因素，并有助于评估这些新兴污染物的生态风险。
