Single molecule imaging of fluorescently labeled proteins on metal by surface plasmons in aqueous solution

We report the first real time imaging of single fluorophores attached to protein molecules on metal surfaces in aqueous solution using surface plasmon resonance fluorescence microscopy. The fluorescence was enhanced by the surface plasmons as theoretically predicted for gold and silver. Active movement of single molecules of the fluorescently labeled motor protein, coupled to the ATPase reaction, was observed on the surfaces of gold and aluminum. This microscopy should prove a powerful tool to directly detect single molecule processes in biomolecule systems organized on a metal surface.