Dynamic imaging of molecular assemblies in live cells based on nanoparticle plasmon resonance coupling

We used molecular-specific gold nanoparticles to monitor epidermal growth factor receptors (EGFR) In live A431 cells over time. Dark-field hyperspectral Imaging, electron microscopy, and electrodynamic modeling were used to correlate optical properties of EGFR-bound plasmonic nanoparticles with receptor regulation state. We showed that receptor trafficking resulted in a progressive red shift of greater than 100 nm In the nanoparticle plasmon resonance wavelength over a time period of 60 min. Furthermore, we demonstrated that changes In peak scattering wavelengths of gold nanoparticles from 546 ± 15 to 574 ± 20, and to 597 ± 44 nm are associated with EGFR trafficking from the cell membrane, to early endosomes, and to late endosomes/multivesicular bodies, respectively. Finally, we used the changes In scattering spectra of EGFR-bound nanoparticles and a straightforward statistical analysis of RGB-channel color images of labeled cells to create near real-time maps of EGFR regulatory states in living cells.