Nanoscale volume confinement and fluorescence enhancement with double nanohole aperture.
Diffraction ultimately limits the fluorescence collected from a single molecule, and sets an upper limit to the maximum concentration to isolate a single molecule in the detection volume. To overcome these limitations, we introduce here the use of a double nanohole structure with 25 nm gap, and report enhanced detection of single fluorescent molecules in concentrated solutions exceeding 20 micromolar. The nanometer gap concentrates the light into an apex volume down to 70 zeptoliter (10(-21) L), 7000-fold below the diffraction-limited confocal volume. Using fluorescence correlation spectroscopy and time-correlated photon counting, we measure fluorescence enhancement up to 100-fold, together with local density of optical states (LDOS) enhancement of 30-fold. The distinctive features of double nanoholes combining high local field enhancement, efficient background screening and relative nanofabrication simplicity offer new strategies for real time investigation of biochemical events with single molecule resolution at high concentrations.
CNRS, Aix Marseille Université, Centrale Marseille, Institut Fresnel, 13013 Marseille, France.
Raju
R
Regmi
Department of Electrical Engineering, University of Victoria, Victoria, British Columbia V8W 3P6, Canada.
Ahmed A
AA
Al Balushi
CNRS, Aix Marseille Université, Centrale Marseille, Institut Fresnel, 13013 Marseille, France.
Hervé
H
Rigneault
Department of Electrical Engineering, University of Victoria, Victoria, British Columbia V8W 3P6, Canada.
Reuven
R
Gordon
CNRS, Aix Marseille Université, Centrale Marseille, Institut Fresnel, 13013 Marseille, France.
Jérôme
J
Wenger