Abstract

Dipicolinic acid (DPA, 2,6-pyridinedicarboxylic acid) is a substance uniquely present in bacterial spores such as that from anthrax (<i>B. anthracis</i>). 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 (λ_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.

Two-dimensional multiwavelength fluorescence spectra of dipicolinic acid and calcium dipicolinate

Sivananthan Sarasanandarajah, Joseph Kunnil, Burt V. Bronk, and Lou Reinisch
Appl. Opt. 44(7) 1182-1187 (2005)

Fluorescence lifetime and intensity of terbium-doped dipicolinic acid in water, HCl, and sodium acetate buffer solutions

Anali Makoui and Dennis K. Killinger
Appl. Opt. 48(4) B111-B118 (2009)

Effect of electron blocking layer on the efficiency of AlGaN mid-ultraviolet light emitting diodes

A. Pandey, W. J. Shin, X. Liu, and Z. Mi
Opt. Express 27(12) A738-A745 (2019)

Transient fluorescence spectroscopy of terbium doped dipicolinic acid: a fluorescence lifetime measurement technique

Anali Makoui and Dennis K. Killinger
J. Opt. Soc. Am. B 26(4) 691-698 (2009)

Proteins and dipicolinic acid released during heat shock activation of Bacillus subtilis spores probed by optical spectroscopy

Alexandra Alimova, A. Katz, Paul Gottlieb, and R. R. Alfano
Appl. Opt. 45(3) 445-450 (2006)