Virus and Bacterial Cell Chemical Analysis by NanoSIMS
In past work for the Department of Homeland Security, the LLNL NanoSIMS team has succeeded in extracting quantitative elemental composition at sub-micron resolution from bacterial spores using nanometer-scale secondary ion mass spectrometry (NanoSIMS). The purpose of this task is to test our NanoSIMS capabilities on viruses and bacterial cells. This initial work has proven successful. We imaged Tobacco Mosaic Virus (TMV) and Bacillus anthracis Sterne cells using scanning electron microscopy (SEM) and then analyzed those samples by NanoSIMS. We were able resolve individual viral particles ({approx}18 nm by 300 nm) in the SEM and extract correlated elemental composition in the NanoSIMS. The phosphorous/carbon ratio observed in TMV is comparable to that seen in bacterial spores (0.033), as was the chlorine/carbon ratio (0.11). TMV elemental composition is consistent from spot to spot, and TMV is readily distinguished from debris by NanoSIMS analysis. Bacterial cells were readily identified in the SEM and relocated in the NanoSIMS for elemental analysis. The Ba Sterne cells were observed to have a measurably lower phosphorous/carbon ratio (0.005), as compared to the spores produced in the same run (0.02). The chlorine/carbon ratio was approximately 2.5X larger in the cells (0.2) versus the spores (0.08), while the fluorine/carbon ratio was approximately 10X lower in the cells (0.008) than the spores (0.08). Silicon/carbon ratios for both cells and spores encompassed a comparable range. The initial data in this study suggest that high resolution analysis is useful because it allows the target agent to be analyzed separate from particulates and other debris. High resolution analysis would also be useful for trace sample analysis. The next step in this work is to determine the potential utility of elemental signatures in these kinds of samples. We recommend bulk analyses of media and agent samples to determine the range of media compositions in use, and to determine how agent composition relates to media composition. After these baseline analyses are performed, the data should be assessed to determine the potential forensic utility of elemental analyses. If promising, validation studies using bulk or NanoSIMS analysis would be necessary.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 956845
- Report Number(s):
- LLNL-TR-405968; TRN: US201014%%1689
- Country of Publication:
- United States
- Language:
- English
Similar Records
Microanalytical Methods for Bio-Forensics Investigations
Chemical imaging of biological materials by NanoSIMS using isotopic and elemental labels
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
BACILLUS
BACTERIAL SPORES
CHEMICAL ANALYSIS
LAWRENCE LIVERMORE NATIONAL LABORATORY
MASS SPECTROSCOPY
PARTICULATES
RESOLUTION
SCANNING ELECTRON MICROSCOPY
SECURITY
SPORES
TARGETS
TOBACCO MOSAIC VIRUS
VALIDATION
VIRUSES