Imaging Quantum Dots Switched On and Off by Photochromic Fluorescence Resonance Energy Transfer (pcFRET)

ABSTRACT

The reversible modulation of the emission of CdSe/ZnS semiconductor nanocrystals (quantum dots) was achieved by binding photochromic diheteroarylethenes and switchable acceptors for fluorescence resonance energy transfer. A biotinylated diheteroarylethene derivative was bound to quantum dots bearing conjugated streptavidin, leading to an intensity decrease as a consequence of energy transfer to the closed form of the acceptor. Interconversion between the open and closed forms by irradiation with 365 and 546 nm light enabled deactivation and activation, respectively, of the FRET process with a corresponding modulation of quantum dot emission, observed both in solution and by sequential wide-field imaging.

Keywords:

• diheteroarylethene
• FRET
• pcFRET
• photochromism
• quantum dot

Acknowledgments

EAJ-E is indebted to the Agencia Nacional de Promoción de la Ciencia y Tecnología (ANPCyT), Fundación Antorchas, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Secretaría de Ciencia, Tecnología e Innovación Productiva (SECyT), the German-Argentine DLR-BMBF-SECyT, and the Universidad de Buenos Aires (UBA) for financial support. TMJ was supported by the Max Planck Society, European Union FP5 Projects QLG1-2000-01260, QLG2-CT-2001-02278, QLK3-CT-2002-01997, and the Center of the Molecular Physiology of the Brain funded by the German Research Council (DFG). EAJ-E and TMJ were the recipients of a joint grant I/77 897 from the Volkswagen Foundation. We are indebted to Bernd Rieger for valuable assistance in the processing of images.