# Visualization of Cellulose Structures with Cesium Labeling and Cryo‐STEM

## TL;DR

This paper introduces a new method using cesium labeling and cryo-STEM to visualize cellulose structures at the atomic level, enabling detailed analysis of soft materials.

## Contribution

The novel use of cesium labeling with cryo-STEM allows visualization of cellulose functional groups at Ångström resolution.

## Key findings

- Cesium labeling combined with cryo-STEM enables visualization of sulfate groups in cellulose nanocrystals.
- Experimental Cs+ positions can be compared with simulations to determine labeled sites along glucose chains.
- The method advances structural analysis of beam-sensitive soft materials at the macromolecular level.

## Abstract

Cellulose, a pivotal component of plant cell walls, is a widely studied biologically derived material with vast potential for numerous applications. However, visualizing the arrangement of individual cellulose molecules within hierarchical structures with electron microscopy has proven challenging due to the material's low contrast and high beam sensitivity. In this study, a novel approach is introduced that combines labeling of cellulose functional groups with high‐contrast cesium counter cations (Cs+) in conjunction with atomic resolution scanning transmission electron microscopy (STEM) in annular dark‐field (ADF) mode at cryogenic temperatures. This technique allows for the identification of individual sulfate groups attached to cellulose chains within cellulose nanocrystal hierarchies at Ångström resolution. Systematic comparison of experimentally obtained interatomic Cs+ distances with simulations potentially enables the localization of the labeled functional groups at the macromolecular level. The method has the potential to elucidate the polymer chain arrangements in nanoscale soft materials.

Cryogenic ADF‐STEM combined with Cs⁺ labelling of sulfate groups enables direct visualization of individual functional groups within cellulose nanocrystal hierarchies at Ångström resolution. Comparison of experimental Cs⁺ positions with simulations allows localization of labeled sites along glucose chains, advancing structural analysis of beam‐sensitive soft materials at the macromolecular level.