Fig. 3. Characterization of intracellular reduction of ionic gold.

Raman spectra (a) of cells treated with either ionic Au–PEG clusters after 240 min (burgundy), 120 min (red), 60 min (orange), 30 min (yellow), Au³⁺ (green), or Na–PEG (blue). Raman mapping (of 2800–3000 peak intensity) with the corresponding bright field and merged images for 240 min treatments of Au–PEG, Au³⁺ and Na–PEG (b). Scale bars for (b) are 20 µm. c Raman spectra of Au–PEG-treated MCF-7 cellular fractions separated using differential centrifugation including the nucleus and large organelles, 15,000 g (red); mitochondria, lysosomes and other medium sized organelles, 100,000 g (green); membrane fragments, 300,000 g (blue); and highly soluble/cytosolic molecules (violet), >300,000 g; and the glass slide without cell fractions (black). d SDS-PAGE stained with Coomassie Blue with intensity plots overlaid of protein from the nuclear fraction of MCF-7 cells without treatment (green), treated with Na–PEG (blue), or Au–PEG (yellow) with standard SDS-PAGE conditions (lighter-shaded colors, left three lanes), or without β-mercaptoethanol (darker-shaded colors, right three lanes).