RESUMO
Dipicolinic acid (DPA, 2,6-pyridinedicarboxylic acid) is a substance uniquely present in bacterial spores such as that from anthrax (B. anthracis). It is known that DPA can be detected by the long-lived fluorescence of its terbium chelate; the best limit of detection (LOD) reported thus far using a large benchtop gated fluorescence instrument using a pulsed Xe lamp is 2 nM. We use a novel AlGaN light-emitting diode (LED) fabricated on a sapphire substrate that has peak emission at 291 nm. Although the overlap of the emission band of this LED with the absorption band of Tb-DPA (lambda(max) doublet: 273, 279 nm) is not ideal, we demonstrate that a compact detector based on this LED and an off-the-shelf gated photodetection module can provide an LOD of 0.4 nM, thus providing a basis for convenient early warning detectors.
Assuntos
Bacillus anthracis/isolamento & purificação , Ácidos Picolínicos/isolamento & purificação , Espectrofotometria Ultravioleta/métodos , Esporos Bacterianos/isolamento & purificação , Aerossóis/química , Bacillus anthracis/química , Medições Luminescentes , Ácidos Picolínicos/análise , Espectrofotometria Ultravioleta/instrumentação , Esporos Bacterianos/química , TérbioRESUMO
We present a compact, robust, solid-state blue-light (490-nm) source capable of greater than 5 mW of output in a TEM(00) mode. This device is an optically pumped, vertical external-cavity surface-emitting laser with an intracavity frequency-doubling crystal.
