Microanalytical Methods for Bio-Forensics Investigations

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Forensics investigations of bio-crime or bio-terrorism incidents require careful analysis of collected evidentiary material. Although the biological markers in the evidentiary material are important (e.g. genomic signatures, protein markers), the elemental make-up of the organisms themselves and the surrounding non-biological material is extremely useful for attributing a specific process and, perhaps, specific persons to the production of the biological agent. This talk will describe the coordinated use of microanalytical techniques such as SEM-EDX, STEM-EDX, and NanoSIMS for generating compositional signatures for bio-forensics investigations. These analytical techniques span length scales from the 50 {micro}m range to the 5nm range. The range ... continued below

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PDF-file: 4 pages; size: 1.4 Mbytes

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Brewer, L N; Weber, P K; Grant, R P; Ghosal, S & Michael, J R February 10, 2006.

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Forensics investigations of bio-crime or bio-terrorism incidents require careful analysis of collected evidentiary material. Although the biological markers in the evidentiary material are important (e.g. genomic signatures, protein markers), the elemental make-up of the organisms themselves and the surrounding non-biological material is extremely useful for attributing a specific process and, perhaps, specific persons to the production of the biological agent. This talk will describe the coordinated use of microanalytical techniques such as SEM-EDX, STEM-EDX, and NanoSIMS for generating compositional signatures for bio-forensics investigations. These analytical techniques span length scales from the 50 {micro}m range to the 5nm range. The range of analytical sensitivities spans from {approx}.5wt% for EDX down to parts per billion for SIMS techniques. In addition, we will discuss the use of spectrum imaging techniques for rapidly extracting the key elemental signatures from large scale data sets. Spectrum imaging techniques combined with multivariate statistical analysis allow for the collection and interrogation or enormous quantities of data without pre-biasing the answer.[1] Spectrum imaging has been used successfully in EDX microanalysis[1] (both in the SEM and TEM) and TOF-SIMS[2]. In this study, a set of test biological agents, ?-irradiated Bacillus thuringiensis (Bt), were examined using the aforementioned microanalytical techniques. The sample set included a number of processing conditions to gauge the ability of these techniques to identify the production methods of these simulated agents. Complementary but distinct forensic signatures were obtained by all three analytical techniques. Figure 1 shows two types of silicate particles observed among the spore material itself. At this length scale, the spores themselves cannot be resolved, but the presence of these silicates is key marker for distinguishing this production route. A STEM-EDX spectrum image from the same material does not show these large silicates but instead shows the segregation of elements such as sulfur and silicon to the extra-cellular material between spores, again a result of the specific process used to produce this simulated agent (Figure 2). NanoSIMS data from the same material also shows the segregation of Si in this preparation. The NanoSIMS data also displays and quantifies the distribution of elements such as fluorine at levels which were not detectable in the STEM-EDX measurements (Figure 3).

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PDF-file: 4 pages; size: 1.4 Mbytes

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  • Presented at: Microscopy and Microanalysis 2006, Chicago, IL, United States, Jul 30 - Aug 03, 2006

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  • Report No.: UCRL-CONF-219020
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 928181
  • Archival Resource Key: ark:/67531/metadc902319

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • February 10, 2006

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  • Sept. 27, 2016, 1:39 a.m.

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  • Nov. 29, 2016, 8:09 p.m.

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Brewer, L N; Weber, P K; Grant, R P; Ghosal, S & Michael, J R. Microanalytical Methods for Bio-Forensics Investigations, article, February 10, 2006; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc902319/: accessed December 10, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.