Fractal Nanoplasmonic Labels for Supermultiplex Imaging in Single Cells

The rapidly increasing need for systems biology stimulates the development of supermultiplex (SM) methods for simultaneously labeling multiple biomolecules/cells with distinct colors. Here we report the development of DNA-engineered fractal nanoplasmonic labels with ultrahigh brightness and photostability for SM imaging in single cells. These color-resolvable nanoplasmonic labels have a uniform size of ∼50 nm with an inner hollow gap of ∼1 nm. The outer shell morphology is highly tunable with the tip aspect ratio covering the range of δ = 0.29–1.66, which supports SM plasmonic imaging exceeding the conventional fluorescence multiplexing limit. We demonstrate the use of these SM labels for quantitative imaging of receptor-mediated endocytosis and intracellular transport of multiple protein–NP structures in a single cell in real time. This SM-plasmonic method sheds light on elucidating complex interactions among protein–NPs in nanotoxicology and facilitates the development of novel nanomedicines for diagnosis and therapy.