Figure 3

Optical spectra for AuNPs before and after introduction to cellular environment. (A) Schematic illustration of the transfer of NPs from water to complete phenol red-free cell culture medium (CPRFM) which results in protein corona formation and possible spectral shift prior to cellular uptake. (B) UV-vis extinction spectra of NPs before transfer to CPRFM, immediately after transfer to CPRFM, and after 24 h of incubation in CPRFM, showing minimal spectral shift in CPRFM prior to cellular uptake. (C) Representative darkfield HS image of Sk-Br-3 cells exposed to 24 μg/mL AuNPs for 24 h and (D) corresponding spectra extracted from the 10 representative cell ROIs denoted in part C. (E) Darkfield HS image of part C's cell ROI 2 with 10 representative ROIs drawn around NP clusters (NPCs). (F) Optical scattering spectra measured from the 10 NPC ROIs defined in part E. Number labels above spectra in parts D and F indicate range (minimum and maximum) of peak wavelengths. For clarity, only 10 representative ROIs are shown in parts C and E.