Web Release Date: January 11,
Flow Cytometric Analysis To Detect Pathogens in Bacterial Cell Mixtures Using Semiconductor Quantum Dots
and
Department of Chemistry, University of Rochester, Rochester, New York 14627, and Department of Radiation Oncology, University of Rochester Medical Center, Rochester, New York 14642
Received for review August 31, 2007. Accepted November 20, 2007.
Abstract:
Compared to a common green organic dye, semiconductor quantum dots (QDs) composed of CdSe/ZnS core/shell bioconjugates display brighter fluorescence intensities, lower detection thresholds, and better accuracy in
analyzing bacterial cell mixtures composed of pathogenic
E. coli O157:H7 and harmless E. coli DH5
using flow
cytometry. For the same given bacterial mixture, QDs
display fluorescence intensity levels that are ~1 order of
magnitude brighter compared to the analogous experiments that utilize the standard dye fluorescein isothiocyanate. Detection limits are lowest when QDs are used as
the fluorophore label for the pathogenic E. coli O157:H7 serotype: limits of 1% O157:H7 in 99% DH5 result,
corresponding to 106 cells/mL, which is comparable to
other developing fluorescence-based techniques for pathogen detection. Finally, utilizing QDs to label E. coli O157:H7 in cell mixtures results in greater accuracy and more
closely approaches the ideal fluorophore for pathogen
detection using flow cytometry. With their broader absorption spectra and narrower emission spectra than
organic dyes, QDs can make vast improvements in the
field of flow cytometry, where single-source excitation and
simultaneous detection of multicolor species without
complicating experimental setups or data analysis is quite
advantageous for analyzing heterogeneous cell mixtures,
both for prokaryotic pathogen detection and for studies
on eukaryotic cell characteristics.
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