Figure 7: Optical microscopy image of a D407 cell loaded with ascorbate-encoded PEG-GENs (a). SERS spectra of as prepared PEG-GENs in aqueous solution (spectrum b in (b)) and inside the cell (spectrum c in (b)) recorded under 633 nm laser line excitation. The asterisks above spectrum c indicate vibrational modes that correspond to cellular components. Spectrum a in (b) represents the Raman spectrum of an individual cell in the absence of nanoparticles, as control.