The analysis of biomolecular interactions using quantum dots (QDs) as both FRET donors and acceptors has become an established technique in the life sciences. This development has been driven by the unique properties of QDs, which include large surfaces for the attachment of biomolecules, high brightness and photostability, strong and spectrally broad absorption, and color-tunability via QD size, shape, and material. Applications include molecular rulers for structural analysis, small-molecule sensors, immunoassays, enzyme assays, nucleic acid assays, fluorescence imaging in-vitro and in-vivo, and molecular logic gates. Here, we will explain the theory of QD-based FRET, review some aspects of QD surface functionalization that are important for FRET, and highlight and discuss the advantages and disadvantages of QDs in FRET-biosensing using both spectroscopy and imaging techniques.
