Electrochemically Controlled Surface Plasmon Enhanced Fluorescence Response of Surface Immobilized CdZnSe Quantum Dots

Cd0.1Zn0.9Se quantum dots with fluorescent emission centered on 614 nm were covalently coupled to a 11-amino-1-undecanethiol monolayer self-assembled on a gold surface. A 594 nm laser was used to excite surface plasmons in the gold film and the resulting surface plasmon enhanced fluorescence of the quantum dots was measured with a photomultiplier. The application of negative potentials (versus Ag/AgCl) led to a decrease in the surface plasmon enhanced fluorescence signal, the fluorescence signal recovered if the cell potential was returned to 0 V or open circuit. These results show that the fluorescence emission of attached quantum dots can be tuned by the application of an electrical potential in an aqueous environment, which may be relevant to quantum dot applications in biosensing.