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Download fileSelf-Assembled Nanoparticle Dimer Antennas for Plasmonic-Enhanced Single-Molecule Fluorescence Detection at Micromolar Concentrations
journal contribution
posted on 2015-08-19, 00:00 authored by Deep Punj, Raju Regmi, Alexis Devilez, Robin Plauchu, Satish Babu Moparthi, Brian Stout, Nicolas Bonod, Hervé Rigneault, Jérôme WengerPlasmonic
antennas offer extremely promising strategies to enhance
single molecule fluorescence sensing and breach the limitations set
by diffraction. However, the technical difficulty and limited availability
of top-down nanofabrication techniques enabling nanometer gap sizes
are limiting the impact of plasmonic antennas for biochemical and
biophysical applications. Here we demonstrate the effectiveness of
self-assembled nanoparticle gap antennas to enhance single molecule
fluorescence detection at high concentrations. For a dimer of 80 nm
gold nanoparticles with 6 nm gap, we isolate detection volumes down
to 70 zL (equivalent to λ3/3600) and achieve 600-fold
fluorescence enhancement, microsecond transit time, and operation
of fluorescence correlation spectroscopy at concentrations exceeding
10 μM. We quantify the near-field detection volume and the fluorescence
enhancement for different self-assembled nanoantenna designs using
fluorescence correlation spectroscopy. The combination of the fabrication
simplicity with the large fluorescence enhancement makes the self-assembled
colloidal nanoparticle gap antennas optimal to extend a wide variety
of single-molecule applications toward the biologically relevant micromolar
concentration regime.