The electrochemical modulation of single molecule fluorescence

Herein is presented our discovery of an electrochemical approach for modulating fluorophores between fluorescent bright states and dim states. We demonstrate how to effectively modulate the fluorescent intensity of organic dye-labelled cell samples on an indium tin oxide surface using electrochemistry with redox-active mediators present in an oxygen scavenger buffer. We showed the electrochemical fluorescence modulation is sensitive to the applied potential and the excitation laser intensity, indicating the possibility of coupled photochemical and electrochemical reactions occurring. We also compared the electrochemical fluorescence modulation of representative oxazine, rhodamine, and cyanine dyes using ATTO 655, Alexa Fluor 488, and Alexa Fluor 647. Different dyes with distinctly different structural core show fluorescence modulation to different extents. The electrochemical fluorescence modulation will be applicable in fluorescence imaging techniques as well as biosensing.