A Quantum‐Dot‐Based Molecular Ruler for Multiplexed Optical Analysis

Nanoshapes and sizes: A time‐resolved multicolor optical analysis of Förster resonance energy transfer (FRET) from a luminescent terbium complex to different semiconductor quantum dots allows the rapid and accurate measurement of the size and shape of different functionalized quantum dots under physiological conditions. This spectroscopic ruler opens the possibility of a simultaneous analysis of different biological processes at sub‐nanomolar concentrations.