期刊
ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 47, 期 7, 页码 3268-3274出版社
AMER CHEMICAL SOC
DOI: 10.1021/es304346p
关键词
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资金
- National Basic Research Program of China [2011CB936001]
- National Science Fund for Distinguished Young Scholars of China [21025729]
- National Natural Science Foundation of China [21227012]
The toxic mechanism of silver nanoparticles (AgNPs) is still debating, partially because of the common cooccurence and the lack of methods for separation of AgNPs and Ag+ in biological matrices. For the first time, Triton-X 114-based cloud point extraction (CPE) was proposed to separate AgNPs and Ag+ in the cell lysates of exposed HepG2 cells. Cell lysates were subjected to CPE after adding Na2S2O3, which facilitated the transfer of AgNPs into the nether Triton X-114-rich phase by salt effect and the preserve of Ag+ in the upper aqueous phase through the formation of hydrophilic complex. Then the AgNP and Ag+ contents in the exposed cells were determined by ICP-MS after microwave digestion of the two phases, respectively. Under the optimized conditions, over 67% of AgNPs in cell lysates were extracted into the Triton X-114-rich phase while 94% of Ag+ remained in the aqueous phase, and the limits of detection for AgNPs and Ag+ were 2.94 mu g/L and 2.40 mu g/L, respectively. This developed analytical method was applied to quantify the uptake of AgNPs to the HepG2 cells. After exposure to 10 mg/L AgNPs for 24 h, about 67.8 ng Ag were assimilated per 10(4) cells, in which about 10.3% silver existed as Ag+. Compared to the pristine AgNPs (with 5.2% Ag+) for exposure, the higher ratio of Ag+ to AgNPs in the exposed cells (10.3% Ag+) suggests the transformation of AgNPs into Ag+ in the cells and/or the higher uptake rate of Ag+ than that of AgNPs. Given that the toxicity of Ag+ is much higher than that of AgNPs, the substantial content of Ag+ in the exposed cells suggests that the contribution of Ag+ should be taken into account in evaluating the toxicity of AgNPs to organisms, and previous results obtained by regarding the total Ag content in organisms as AgNPs should be reconsidered.
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