Electronic Military & Defense magazine was developed for engineers, program managers, project managers, and those involved in the design and development of electronic and electro-optic systems for military, defense, and aerospace applications.
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Techniques Biothreat Detection Using Intrinsic Autofluorescence Advanced optoelectronic techniques that detect natural light emissions from cells and tissues could help improve the identification and assessment of biological threats like anthrax. By Vinod Jyothikumar T he threat of bioterrorism has become a major in the range from 250 nm to nearly 800 nm have been challenge for the 21st century. However, the found, isolated, and resynthesized (Figure 1). Live potential of infectious agents as bioweapons bacteria and spores contain a variety of intracellular has been recognized for centuries. Throughout biomolecules associated with energy yielding reactions. history there have been attempts to initiate infectious Some of these biomolecules have specific excitation disease outbreaks and epidemics during warfare. In the and emission wavelength spectra that characterize their past decade, the attention of the biomedical community, intrinsic fluorescence. The fluorescent characteristics of as well as governments and the United Nations, has many such molecules have been studied, and they offer increasingly focused on the threat of bioterrorism, a number of expedient options for biological detection. especially the use of biological and/or chemical weapons The ideal target biomolecule should have an intrinsic against military and civilian populations. As an example, fluorescence spectrum that distinguishes it from other there is now much interest concerning microbial infection materials and have sufficient fluorescence intensity to and bioterrorism in the medical microbiology and produce a strong signal. In general, shorter excitation immunology communities. wavelengths have higher energy and thus are likely to Optical technologies offer a repertoire of fast, simple, produce fluorescence in more types of materials. and reliable techniques that can be applied for the identification and characterization of microorganisms. Traditional methods of microbial identification based on biochemical, physiological, and morphological criteria are often time-consuming and laborious, involve numerous reagents, and may have difficulty in the distinction of closely related organisms. Molecular DNA analysis methods developed recently provide a more reliable differentiation of microorganisms at the species level; however, these methods are also reagent- and time-intensive. Other techniques in use include infrared spectroscopy, flow cytometry, and chemiluminescence. Various earlier studies have proposed the use of fluorescence spectra for rapid microbial identification. Fluorescence labeling is commonly applied along with chromatography, dot-blot, and fluorescence in situ hybridization. Some studies included bacterial characterization based on their intrinsic fluorescence or autofluorescence. This article addresses the potential application of natural fluorophores in assessing biothreat or other agents by substances that possess intrinsic fluorescence, which is called autofluorescence. Figure 1: Representative intrinsic biomarkers responsible for autofluorescence in bacterial A great number of fluorescent materials emitting cells and spores 18 Electronic Military & Defense ■ www.vertmarkets.com/electronics