Cellulose, being a renewable and abundant biopolymer, has garnered significant attention for its unique properties and potential applications in hybrid materials. Understanding the hierarchical arrangement of cellulose nanofibers is crucial for developing cellulose-based materials with enhanced mechanical properties. In this study, the use of Scanning Electron Diffraction (SED) is presented to map the nanoscale orientation of cellulose fibers in a bio-composite material with a preserved wood cell structure. The SED data provides detailed insights into the ordering of cellulose with an extraordinary resolution of approximate to 15 nm. It enables a quantitative analysis of the fiber orientation over regions as large as entire cells. A highly organized arrangement of cellulose fibers within the secondary cell wall is observed, with a gradient of orientations toward the outer part of the wall. The in-plane fiber rotation is quantified, revealing a uniform orientation close to the middle lamella. Transversely sectioned material exhibits similar trends, suggesting a layered cell wall structure. Based on the SED data, a 3D model depicting the complex helical alignment of fibers throughout the cell wall is constructed. This study demonstrates the unique opportunities SED provides for characterizing the nanoscale hierarchical arrangement of cellulose nanofibers, empowering further research on a range of hybrid materials. Fundamental knowledge about the hierarchical arrangement of cellulose nanofiber is of great importance in developing new cellulose-based hybrid materials. Scanning electron diffraction is employed to map the cellulose nanofiber orientations throughout a wood-derived bio-based material. SED data reveals insights into cellulose alignment and enables precise quantitative fiber orientation analysis with a nanoscale spatial resolution.image

Natural biocomposites such as wood and plant cell walls exhibit prominent mechanical properties largely attributed to the nanoscale organization of fibrous components, such as cellulose, which often adopt chiral arrangements. However, resolving the three-dimensional (3D) arrangement of these structures at the nanoscale remains a significant challenge, particularly in beam-sensitive materials. This study introduces a method for 3D reconstruction of orientation based on scanning electron diffraction (SED), enabling the quantitative mapping of chiral supramolecular organization with sub-100 nm spatial resolution. By acquiring low-dose SED data at multiple tilt angles and applying a symmetry-based reconstruction algorithm, we resolved the 3D orientation of cellulose fibrils in native oat husk and birch wood. Our results reveal a multilayered cell wall architecture with alternating helical handedness, providing precise measurements of 3D fibril orientation. This method reveals complex hierarchical structures at the nanoscale, enabling rapid data acquisition and analysis using widely available instrumentation. The ability to resolve such chiral organization provides insights into material properties as well as opportunities for designing bioinspired materials with tunable mechanical and functional properties that extend far beyond natural biocomposite materials.

Chitin is a structural polysaccharide that forms hierarchically organized nanofibrils in organisms such as arthropod cuticles, mollusk shells, and fungal cell walls. The organization of these nanofibrils, ranging from layers to helicoidal arrangements, impacts the mechanical, protective, and optical properties of biological materials. This study employs three-dimensional scanning electron diffraction (3D-SED) to investigate the nanoscale organization of native chitin in the wings of the ladybug beetle. The SED data confirm the presence of chitin in both the dorsal elytron and the thin membrane of the hindwing. In the dorsal elytron, 3D-SED reveals a multilayered, plywood-like architecture consisting of chitin aligned parallel to the surface, with densely packed fibrils in the inner layers and bundled aggregates in the outer layers. The much thinner hindwing exhibits left-handed helicoidal arrangements, characteristic of chiral fibrillar structures. These findings demonstrate the capability of 3D-SED to resolve hierarchical architectures in beam-sensitive biological tissues, providing nanoscale insights into the structural diversity of chitin and its role in defining the mechanical properties of these tissues.

Transparent wood composites provide new functionalities through active additives distributed at the nanoscale. Scalable nanotechnology includes processing where nanoparticles and molecules are brought into the dense wood cell wall. A novel cell wall swelling step through green chemistry is therefore investigated. Sub-zero centigrade NaOH treatment provides extensive cell wall swelling. Cell wall accessibility is vastly increased so that chemicals can readily impregnate the nanostructured cell wall. Transparent wood with a thickness of up to 15 mm can therefore be fabricated. The optical transmittance and the attenuation coefficient are improved since the polymer is distributed inside the cell wall as a matrix for the nanoscale cellulose fibrils. The proposed technology paves the way for scalable wood nanoengineering.