Pt. Charles et Aw. Kusterbeck, Trace level detection of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by microimmunosensor, BIOSENS BIO, 14(4), 1999, pp. 387-396
Reported in this paper is the development and characterization of a highly
sensitive microcapillary immunosensor for the detection of the explosive, h
exahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The immunosensor exploits ant
ibodies as recognition elements for target antigens, fluorescence dye conju
gates for reporter molecules and fused silica microcapillaries for its high
surface-to-volume ratio. Detection of RDX with the microcapillary immunose
nsor requires covalent immobilization of anti-RDX antibodies on the inner c
ore of the microcapillaries via heterobifunctional cross-linker chemistry.
Subsequent saturation of all antibody binding domains follows with a synthe
tically prepared fluorescent analog of RDX. Displacement immunoassays were
performed with the microcapillary immunosensor with the injection of unlabe
led RDX at concentration levels from 1 part-per-trillion (pptr) to 1000 par
t-per-billion (ppb). As unlabeled RDX reaches the binding domain of the ant
ibody, fluorescent RDX analog is displaced from the antibody, flows downstr
eam and is measured by a spectrofluorometer. Fluorescence measurements of t
he displaced fluorescent RDX analog were equated to a standard calibration
curve to quantify sample concentration. Complete evaluation of the RDX micr
ocapillary immunosensor for selectivity and sensitivity was performed based
on the following criteria: variable flow rates, antibody cross-reactivity,
reproducibility and cross-linker (carbon spacer) comparison. Results indic
ate the lowest detectable limit (LDL) for RDX is 10 pptr (ng/l) with a line
ar dynamic range from 0.1 to 1000 ppb (mu g/l). (C) 1999 Elsevier Science S
.A. All rights reserved.