Gold nanorods coated with multilayer polyelectrolyte as contrast agents for multimodal imaging

Gold nanorods coated with multilayer polyelectrolyte is reported as a biocompatible optical probe with capability for dark-field imaging and for electron microscopy of cancer cells. Transferrin (Tf) was conjugated to the polyelectrolyte-coated nanorods for targeted in vitro delivery to cancer cells. Dark-field imaging was used to confirm the receptor-mediated uptake of nanorods into HeLa cells, which is known to overexpress the transferrin receptor (TfR). Minimal uptake was observed with untargeted nanorods. Electron microscopy was used to confirm that the intracellular uptake of the nanorods predominantly occurred via the Tf-TfR interaction and the nanorods localized in vesicular structures such as endosomes.