Abstract
Quantum dots are bright, photostable fluorophores used extensively to investigate biological processes. In this study, we report that bromocresol green (BCG) at low micromolar concentrations rapidly, efficiently and reversibly quenches the fluorescence of commercial quantum dots having a wide range of functionalities. The broad utility of BCG quenching of quantum dots in cell biology is showed in quantitative assays of trafficking of the β(2) -adrenergic receptor (β(2) AR) and the cystic fibrosis transmembrane conductance regulator (CFTR).