02/29/2016

Directly Revealing Atomic-Scale Phosphorus

A new approach enables atomic-scale analysis in soft biological materials.

The Science

Researchers examined the chemical identity and three-dimensional (3D) position of atoms in soft biological materials with a new approach using atom probe tomography (APT).

The Impact

An extension of the new specimen preparation technique can further enhance the APT study of organic and inorganic materials and nanoparticles relevant to energy and the environment.

Summary

The chemical identity and 3D position of individual atoms in inorganic materials can be revealed using the powerful APT technique, which combines mass spectrometry with advanced microscopy. However, use of APT to study soft biological materials has been limited because of difficulties in specimen preparation. To address this problem, researchers from the Department of Energy’s (DOE) Environmental Molecular Sciences Laboratory (EMSL), and Pacific Northwest National Laboratory developed an advanced specimen preparation approach to study soft biological materials using APT. The new specimen preparation approach involves embedding ferritin in an organic polymer resin that lacks nitrogen to provide chemical contrast for visualizing atomic distributions. The team used the Helios Nanolab dual-beam focused ion beam/scanning electron microscope (FIB/SEM) at EMSL, a DOE scientific user facility, to carve and lift out an appropriate sample for APT analysis. Then, using EMSL’s APT, they directly mapped the distribution of phosphorus at the surface of the ferrihydrite mineral, thereby providing insight into the role of phosphorus in stabilizing the ferrihydrite structure. The robust sample preparation method can be directly extended to further enhance the study of biological, organic, and inorganic nanomaterials relevant to energy and the environment.

Principal Investigator(s)

James Evans
Environmental Molecular Sciences Laboratory
[email protected]

Funding

This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research, including support of the Environmental Molecular Sciences Laboratory, a DOE Office of Science user facility; and the Chemical Imaging Initiative conducted under the Laboratory-Directed Research and Development Program at Pacific Northwest National Laboratory.

References

Perea, D. E., J. Liu, J. Bartrand, Q. Dicken, S. T. Thevuthasan, N. D. Browning, and J. E. Evans. 2016. “Atom Probe Tomographic Mapping Directly Reveals the Atomic Distribution of Phosphorus in Resin Embedded Ferritin,” Scientific Reports 6(22321), DOI: 10.1038/srep22321.