Analysis of the Distribution Pattern of Chromium Species in Single Cells

The patterning of distribution models for specific heavy metal species in biological cells is highly important for elucidating their effect on single cells or in a living organism. For this purpose, the variation of chromium levels and the distribution patterns of chromium species in single-cell subjects are investigated by culturing two kinds of native cells (i.e., HeLa cells and MCF-7 cells) in the presence of either Cr(III) or Cr(VI). The analysis of single cells is performed with time-resolved inductively coupled plasma mass spectrometry. We found that the total chromium level in the single cells after culturing in a Cr(VI)-enriched medium is higher than that for those single cells cultured in a Cr(III)-reinforced medium. It is interesting to see that at certain culturing conditions, the chromium level in single individual cells increases linearly with Cr(III) concentration in the culture medium, whereas it increases exponentially with Cr(VI) concentration. This indicated that Cr(VI) is more prone to penetrate the cells with respect to Cr(III), and after a concentration threshold, considerably more Cr(VI) enters into the interior of HeLa cells or MCF-7 cells.