Quantification of the uptake of silver nanoparticles and ions to HepG2 cells.

The toxic mechanism of silver nanoparticles (AgNPs) is still debating, partially because of the common co-occurrence 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 μg/L and 2.40 μg/L, respectively. This developed analytical method w...