Nanoparticle Sizing and Potential Quality Control of Sols Using a Unique Fluorescence Anisotropy Probe and 3D Contour Anisotropy Mapping.
Spectroscopic properties of the particle sizing fluorophore Dipole Blue are reported. The probe is cationic in nature, highly water-soluble, and strongly adheres to anionic silica surfaces by electrostatic interactions, as is demonstrated here by Ludox SM 30. The probe has a distinct absorbance band centered at 320 nm, and the fluorescence emission band is Stokes-shifted 100 nm with a peak centered at 426 nm. From time-correlated single-photon counting experiments, the fluorescence lifetime was found to be adequately described by a three-exponential decay model with an intensity-averaged lifetime of 15.6 ns. Perrin graph analysis of steady-state anisotropy shows the presence of silica particles with a radius of (5.44 ± 0.16) nm, which, considering the distribution of particle sizes, is in reasonable agreement with 3.5 nm found from dynamic light scattering experiments.
Department of Chemistry and Biochemistry and Institute of Fluorescence, The Columbus Center, University of Maryland Baltimore County, 701 East Pratt Street, Baltimore, Maryland 21202, United States.
Jan
J
Karolin
Department of Chemistry and Biochemistry and Institute of Fluorescence, The Columbus Center, University of Maryland Baltimore County, 701 East Pratt Street, Baltimore, Maryland 21202, United States.
Chris D
CD
Geddes
Dipole Blue; Ludox; Perrin analysis; colloidal silica; fluorescence anisotropy; particle sizing fluorophore