Figure 5

Representative HS images, corresponding spectra, and TEM images through time following NP introduction to cells. Cells were exposed to NPs at a dose of 24 μg/mL for (A) 2-, (B) 5-, (C) 10-, and (D) 24-h incubation. The continual increase in NP cluster size within cells with increased exposure time seen in cellular TEM images suggests that intracellular agglomeration of NPs contributes to the measured spectral shifts. Spectra are normalized to 1 for ease of comparison. HS images were taken at 5 μm above the slide plane to capture spectral contributions from intracellular NPs (see ‘Methods’ section and Additional file 1).