Mapping the path to Cryogenic Atom Probe Tomography Analysis of biomolecules

TL;DR

This paper explores the potential of cryogenic atom probe tomography (APT) for analyzing biomolecules, specifically amino acids in frozen solutions, aiming to establish guidelines for its effective application in biological research.

Contribution

It systematically investigates cryo-APT analysis of amino acids, examining sample support, preparation, and conditions to advance the technique's use in biological materials.

Findings

Amino acids can be analyzed in frozen aqueous solutions using cryo-APT.

Sample support and preparation significantly influence analysis outcomes.

Guidelines for cryo-APT analysis of biomolecules are proposed.

Abstract

The understanding of protein structure, folding, and interaction with other proteins remains one of the grand challenges of modern biology. Tremendous progress has been made thanks to X-ray- or electron-based techniques that have provided atomic configurations of proteins, and their solvation shell. These techniques though require a large number of similar molecules to provide an average view, and lack detailed compositional information that might play a major role in the biochemical activity of these macromolecules. Based on its intrinsic performance and recent impact in materials science, atom probe tomography (APT) has been touted as a potential novel tool to analyse biological materials, including proteins. However, analysis of biomolecules in their native, hydrated state by APT have not yet been routinely achieved, and the technique's true capabilities remain to be demonstrated. Here, we present and discuss systematic analyses of individual amino-acids in frozen aqueous solutions on two different nanoporous metal supports across a wide range of analysis conditions. Using a ratio of the molecular ions of water as a descriptor for the conditions of electrostatic field, we study the fragmentation and behavior of those amino acids. We discuss the importance sample support, specimen preparation route, acquisition conditions and data analysis, to pave the way towards establishing guidelines for cryo-APT analysis of biomolecules.