3D sub-nanometer analysis of glucose in an aqueous solution by cryo-atom probe tomography

Abstract

Atom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT’s capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.

Frozen n-Tetradecane Investigated by Cryo-Atom Probe Tomography

“…For the first range from C1 to C3, the highest peaks at m/q = 15, 29, and 43 u/e can be identified to C n H 2n+1 + with n = 0-3, that is, alkyl chains having lost one hydrogen. Similar distributions have already been observed in various measurements of polymer layers (Kelly et al, 2009;Prosa et al, 2010) or of dissolved glucose molecules in an aqueous solution (Schwarz et al, 2021). In the range between C4 and C7, the highest peak of the group occurs at m/q = 56, 70, 84, and 98 u/e, which corresponds to the molecular formula of C 4+n H 8+2n , an alkyl having lost two hydrogen atoms.…”

“…Recent cryo-APT studies focused on pure water (Schwarz et al, 2020) and deuterium oxide (El-Zoka et al, 2020) or aqueous solutions (Schwarz et al, 2021). Especially in the latter one, the importance of a profound knowledge about the basic evaporation and fragmentation behavior of linear alkane chains was emphasized.…”

“…The development of cryogenic transfer suitcases, which allow the transport of actively cooled samples between different analytical instruments under vacuum conditions, laid the foundation for the analysis of frozen samples (Schreiber et al, 2018; Stephenson et al, 2018; El-Zoka et al, 2020; Perea et al, 2020; Qiu et al, 2020 a , 2020 b , 2020 c ; Schwarz et al, 2020, 2021; Stender et al, 2021). Consequently, various new approaches and preparation routes were developed, providing a further step toward the reliable analysis of frozen liquids (Stender et al, 2021).…”

“…Recently, we demonstrated the preparation and analysis of bulk frozen liquids with the example of water tips (Schwarz et al, 2020) and a saturated glucose solution (Schwarz et al, 2021). Quite extended datasets of frozen liquids allow a fundamental study of the evaporation and fragmentation behavior of liquids, hopefully, in the future, also leading to reliable studies of biological samples using liquids as an embedding matrix, studies of catalytic reactions at liquid/solid interfaces or interfaces in emulsions and wet corrosion mechanism.…”

A Modular Atom Probe Concept: Design, Operational Aspects, and Performance of an Integrated APT-FIB/SEM Solution

“…The modular version was specifically designed to simplify at least part of the process and eliminate unnecessary sources of error. Thus, the group has succeeded in performing fundamental analyses on frozen liquids (Schwarz et al, 2020(Schwarz et al, , 2021. The preparation of these samples with intermediate transport in a shuttle solution is also possible.…”