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Journal of Clinical Microbiology, Feb 1995, 336-341, Vol 33, No. 2
LK Cao, GP Anderson, FS Ligler and J Ezzell
A fiber optic biosensor was used to detect the fraction 1 (F1) antigen from
Yersinia pestis, the etiologic agent of plague. The instrument employs an
argon ion laser (514 nm) to launch light into a long-clad fiber and
measures the fluorescence produced by an immunofluorescent complex formed
in the evanescent wave region. This sensing area is a short section (12.5
cm) at the end of the optical fiber from which the cladding has been
removed and in which the silica core has been tapered. Capture antibodies,
which bind to F1 antigen, were immobilized on the core surface to form the
basis of the sandwich fluoroimmunoassay. The ability to detect bound F1
antigen was provided by adding tetramethylrhodamine-labeled anti-plaque
antibody to form fluorescent complexes. The evanescent wave has a limited
penetration depth (< 1 lambda), which restricts detection of the
fluorescent complexes bound to the fiber's surface. The direct correlation
between the F1 antigen concentration and the signal provided an effective
method for sample quantitation. This method achieved a high level of
accuracy for determining F1 antigen concentrations from 50 to 400 ng/ml in
phosphate-buffered saline, serum, plasma, and whole blood, with a 5- ng/ml
limit of detection. Subsequent blind studies, which included serum samples
from patients, yielded results in good agreement with measurements by
enzyme-linked immunosorbent assay. A major advantage of the fiber optic
biosensor is that results can be generated within minutes while isolating
the user from hazardous samples. These factors favor development of this
biosensor into a facile and rapid diagnostic device.
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
Detection of Yersinia pestis fraction 1 antigen with a fiber optic biosensor
Geo-Centers Inc., Fort Washington, Maryland.
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