Directional surface plasmon-coupled emission: A new method for high sensitivity detection.
Fluorescence emission is nearly isotropic in space. With typical optical components the collection efficiency is 1% or less. In this preliminary report, we describe a novel approach to transforming the normally isotropic emission into directional emission with a collection efficiency near 50%. This can be accomplished for fluorophores located near a semi-transparent silver film on a glass substrate. The emission couples with the surface plasmon resonance on the silver surface and enters the transparent substrate at a sharply defined angle, the surface plasmon angle for the emission wavelength. We estimate that 40-70% of the total emission enters the substrate at the plasmon angle and can thus be directed towards a detector. Background emission from fluorophores distant from the silver does not couple with the plasmon and is not detected. Different emission wavelengths couple at different angles allowing spectral discrimination without additional optics. Surface plasmon-coupled emission represents a new technology which can be used for high detection efficiency with microfluidic and/or surface-bound assay formats.
Lakowicz
Joseph R
JR
University of Maryland at Baltimore, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, MD 21201, USA. cfs@cfs.umbi.umd.edu
Malicka
Joanna
J
Gryczynski
Ignacy
I
Gryczynski
Zygmunt
Z
D005456:Fluorescent Dyes / Q000737:chemistry; D011142:Polyvinyl Alcohol / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D020349:Surface Plasmon Resonance
D005456:Fluorescent Dyes; D012235:Rhodamines; D012834:Silver; D011142:Polyvinyl Alcohol; C050829:sulforhodamine 101