Metallic colloid wavelength-ratiometric scattering sensors.
Gold and silver colloids display strong colors as a result of electron oscillations induced by incident light, which are referred to as the plasmon absorption. This absorption is dependent on colloid-colloid proximity, which has been the basis of absorption assays using colloids. We now describe a new approach to optical sensing using the light scattering properties of colloids. Colloid aggregation was induced by avidin-biotin interactions, which shifted the plasmon absorption to longer wavelengths. We found the spectral shift results in changes in the scattering at different incident wavelengths. By measuring the ratio of scattered intensities at two incident wavelengths, this measurement was made independent of the total colloid concentration. The high scattering efficiency of the colloids resulted in intensities equivalent to fluorescence when normalized by the optical density of the fluorophore and colloid. This approach can be used in a wide variety of assay formats, including those commonly used with fluorescence detection.
Roll
David
D
Center for Fluorescence Spectroscopy, University of Maryland at Baltimore, Department of Biochemistry and Molecular Biology, 725 West Lombard Street, Baltimore, Maryland 21201, USA.
Malicka
Joanna
J
Gryczynski
Ignacy
I
Gryczynski
Zygmunt
Z
Lakowicz
Joseph R
JR
D000345:Affinity Labels; D001360:Avidin / Q000737:chemistry; D001710:Biotin / Q000737:chemistry; D003102:Colloids / Q000737:chemistry*; D017979:Gold Colloid / Q000737:chemistry; D008027:Light; D008670:Metals / Q000737:chemistry*; D012235:Rhodamines; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance
D000345:Affinity Labels; D003102:Colloids; D017979:Gold Colloid; D008670:Metals; D012235:Rhodamines; D001360:Avidin; D001710:Biotin; C029773:rhodamine B