Fluorescence Resonance Energy Transfer Between a Fluorescent Protein and Commercially Available Quantum Dots

Semi-conductor quantum dots (QDs) are exceptionally bright fluorescent emitters that have garnered much attention over the past decade as an emerging tool for biomedical investigations. QDs offer several advantages over organic fluorophores, including up to 1,000-fold higher brightness than most organic fluorophores, very photostable, the “tunable emission” allowing for desired emission spectrum, and the ability to excite almost all QDs by a single (UV) wavelength [1,2]. The QDs typically used in the visible wavelength range are CdSe/ZnS core-shell nanoparticles; the CdSe center confers the particle its unique optical properties, while the ZnS shell serves as a passivation layer, protecting the core from oxidation and enhancing the quantum yield. In addition, an organic coating is necessary in order to confer water-solubility to the QD for biological studies [1,2].