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Title: Microanalytical Methods for Bio-Forensics Investigations

Abstract

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. Themore » 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).« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
928181
Report Number(s):
UCRL-CONF-219020
Journal ID: ISSN 1431-9276; TRN: US200815%%768
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Journal Volume: 12; Journal Issue: S02; Conference: Presented at: Microscopy and Microanalysis 2006, Chicago, IL, United States, Jul 30 - Aug 03, 2006
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BACILLUS; BIOLOGICAL MARKERS; DISTRIBUTION; FLUORINE; MICROANALYSIS; MICROSCOPY; PROCESSING; PRODUCTION; PROTEINS; SEGREGATION; SILICATES; SILICON; SPORES; SULFUR

Citation Formats

Brewer, L N, Weber, P K, Grant, R P, Ghosal, S, and Michael, J R. Microanalytical Methods for Bio-Forensics Investigations. United States: N. p., 2006. Web. doi:10.1017/S1431927606064245.
Brewer, L N, Weber, P K, Grant, R P, Ghosal, S, & Michael, J R. Microanalytical Methods for Bio-Forensics Investigations. United States. https://doi.org/10.1017/S1431927606064245
Brewer, L N, Weber, P K, Grant, R P, Ghosal, S, and Michael, J R. 2006. "Microanalytical Methods for Bio-Forensics Investigations". United States. https://doi.org/10.1017/S1431927606064245. https://www.osti.gov/servlets/purl/928181.
@article{osti_928181,
title = {Microanalytical Methods for Bio-Forensics Investigations},
author = {Brewer, L N and Weber, P K and Grant, R P and Ghosal, S and Michael, J R},
abstractNote = {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).},
doi = {10.1017/S1431927606064245},
url = {https://www.osti.gov/biblio/928181}, journal = {},
issn = {1431-9276},
number = S02,
volume = 12,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2006},
month = {Fri Feb 10 00:00:00 EST 2006}
}

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