SINGLE MOLECULE SPECTROSCOPY STUDY ON FLUORESCENCE ENHANCEMENT BY NOBLE METAL NANOPARTICLES

Abstract

NOBLE METAL NANOPARTICLES (NPS) EXHIBIT UNIQUE OPTICAL PROPERTIES OWING TO THEIR LOCALIZED SURFACE PLASMON RESONANCE, AND THIS LEADS TO THE ENHANCEMENT OF A NUMBER OF OPTICAL RESPONSES SUCH AS FLUORESCENCE. IN THE FIRST PART, PARAMETERS AFFECTING FLUORESCENCE ENHANCEMENT HAVE BEEN ANALYZED USING FDTD SIMULATIONS IN A MULTIDIMENSIONAL MANNER FOR THE OPTIMIZED CONDITIONS. THE FLUORESCENCE ENHANCEMENT IS STRONGLY DISTANCE DEPENDENT, MAKING IT AN IDEAL TOOL FOR MOLECULAR CONFORMATION CHANGE DETECTION. WE HAVE DEMONSTRATED THE METAL ENHANCED FLUORESCENCE COULD REVEAL DNA HAIRPIN UNFOLDING AND REFOLDING EVENTS AT SINGLE MOLECULE LEVEL USING AN INTERLACED OPTICAL FORCE-FLUORESCENCE SPECTROSCOPY, WITH AN IMPROVED FLUORESCENCE INTENSITY AND PHOTO-STABILITY. WHEN MULTIPLE METAL NPS ARE PLACED IN CLOSE VICINITY, FLUORESCENCE COULD BE FURTHER ENHANCED DUE TO THE PLASMON COUPLING EFFECT. BY ATTACHING A SERIES OF GOLD NANOROD WITH DIFFERENT GAPS ON SELF-ASSEMBLED DNA ORIGAMI NANO-BREADBOARD, WE HAVE