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

Controlling the Reaction of Nanoparticles for Hollow Metal Oxide Nanostructures

Hollow nanostructures of metal oxides have found broad applications in different fields. Here, we reported a facile and versatile synthetic protocol to prepare hollow metal oxide nanospheres by modulating the chemical properties in solid nanoparticles. Our synthesis design starts with the precipitation of urea-containing metal oxalate, which is soluble in water but exists as solid nanospheres in ethanol. A controlled particle hydrolysis is achieved through the heating-induced urea decomposition, which transforms the particle composition in an outside-to-inside style: The reaction starts from the surface and then proceeds inward to gradually form a water-insoluble shell of basic metal oxalate. Such a reaction-induced solubility difference inside nanospheres becomes highly efficient to create a hollow structure through a simple water wash process. A following high temperature treatment forms hollow nanospheres of different metal oxides with structural features suited to their applications. For example, a high performance anode for Li-ion intercalation pseudocapacitor was demonstrated with the hollow and mesoporous Nb₂O₅ nanospheres