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Site-Specific Bioimaging

Summary:

In collaboration with scientists at the Laboratory for Cell Biology (LCB) within the National Cancer Institute (NCI) of the National Institutes of Health (NIH), we have outlined steps necessary for developing a comprehensive program in the differentiation between cancerous and healthy cellular material. The role of NIST is to provide mass spectrometry-based imaging methods for the site-specific localization of biochemical changes within and around single cells, as well as tissue. In the initial stages of this collaboration, cluster secondary ion mass spectrometry (SIMS) is used to image aggregates of Escherichia coli. The simplicity of this cell line has allowed for scientists at the NIH/NCI to test proper cell preparation methods needed for SIMS analysis, and for NIST to verify the ability of the imaging modality to provide biologically relevant chemical signatures before introducing specially targeted cell lines.

Description:

This research is aimed at developing the methods necessary for measuring the site-specific chemical differentiation between diseased and healthy cell lines. The long-term strategic plan is to use these differences to develop disease-specific biomarkers based on multiple mass spectrometry and optical imaging methods in one comprehensive data set. This information will be used to develop the metrology tools necessary for atmospheric pressure-based, clinical diagnostics by imaging mass spectrometry.

In this preliminary work, cluster SIMS imaging is used to search for biologically relevant signals from aggregates of Escherichia coli. Assessments of the current state of sample preparation methods for such a purpose will be evaluated and directions for future experiments within the project goals are determined. Inorganic chemical signatures are localized to the cellular material and absent from the silicon support, verifying the ability of SIMS to obtain biologically relevant signals where appropriate. Based on images such as those below, we have determined the changes necessary for enhancing organic signals while minimizing extracellular inorganic signals. We have also identified the first disease pathway for study within a specially chosen cell line. Efforts are advancing for the second stage of this project.

Major Accomplishments:

Aggregates of Escherichia coli prepared by scientists at NIH/NCI specifically for testing ability of SIMS imaging to produce biologically relevant chemical signatures

Cluster SIMS imaging using Bi3+ primary ions was employed to image aggregates of Escherichia coli on a silicon support

Inorganic chemical signatures of the cellular material were chemically mapped

Changes in sample preparation methods were made in order to enhance organic chemical signatures within the cellular material

A specific cell line was identified in order to study a prominent disease pathway in the next round of experiments, where the goal is to image the chemical changes manifested by controlled expression of targeted molecules

Cluster SIMS image of E.Coli using tribismuth cation

Start Date:

February 1, 2007

End Date:

ongoing

Lead Organizational Unit:

mml

Facilities/Tools Used:

Advanced Measurement Laboratory

IonTOF-IV Time-of-Flight Secondary Ion Mass Spectrometer with Bi3+ Primary Ions

Contact

Christopher Szakal
301-975-3816 Telephone
christopher.szakal@nist.gov

100 Bureau Drive, MS 8371
Gaithersburg, MD  20899-8371