The new small-angle X-ray scattering beamline for materials research at PETRA III: SAXSMAT beamline P62

Multimodal structural humidity-response of cellulose nanofibril foams derived from wood and upcycled cotton textiles

We have produced foams from cellulose nanofibrils from upcycled cotton (upCNF) and wood (wCNF) through unidirectional (UIT) and multidirectional ice-templating (MIT) and investigated the structural humidity response through in-situ WAXS, SAXS, and micro tomography (μCT) between 10 and 95 % relative humidity (RH). The upCNF and wCNF WAXS patterns displayed a shape- and position shift as the RH was increased, with a compression in the (200) direction and an elongation in the (004) direction. The average separation distance extracted from the 1D SAXS patterns revealed no significant change for the upCNF foams regardless of RH and processing route, while a significant increase was observed for the wCNF foams. The μCT measurements of the upCNF foams showed a slight shift in macropore distribution towards larger pores between 50 and 80 % RH which can be attributed to the weakening and partial disintegration of the pore wall as more moisture is introduced. The humidity-induced structural alterations of the upCNF foam were significantly lower compared to the wCNF foams, confirming our claim of upCNF being more moisture resistant than wCNF foams.

Buffer Specificity of Ionizable Lipid Nanoparticle Transfection Efficiency and Bulk Phase Transition

Lipid nanoparticles (LNPs) are efficient and safe carriers for mRNA vaccines based on advanced ionizable lipids. It is understood that the pH-dependent structural transition of the mesoscopic LNP core phase plays a key role in mRNA transfer. However, buffer-specific variations in transfection efficiency remain obscure. Here we analyze the effect of the buffer type on the transfection efficiency of LNPs. We find that LNPs formulated with the cationic ionizable lipids DLin-MC3-DMA (MC3), SM-102, and ALC-315 in citrate compared to phosphate and acetate buffers exhibit earlier onset and stronger mRNA-GFP expression in vitro. Using synchrotron small-angle X-ray scattering (SAXS) we determine the buffer specificity of the pH-dependent structure of ionizable lipid/cholesterol/water mesophases that serve as model systems for the LNP core phase. The results show that the phase transition from inverse micellar to inverse hexagonal with decreasing pH is shifted to a lower transition pH for acetate and phosphate compared with citrate buffer. Based on continuum theory and ion-specific adsorption obtained from all-atom MD simulations, we propose a mechanism for buffer specificity. Citrate stabilizes the inverse hexagonal phase thus shifting the formation of HII to a higher pH. By contrast, phosphate and acetate stabilize LII. It stands to reason that the inverse micellar to inverse hexagonal transition, which is facilitated in citrate buffer, enables a sensitized pH response of the LNP core phase. This, in turn, enhances endosomal release efficiency and accounts for the earlier onset of gene expression observed in LNPs prepared with citrate buffer.

Moisture-Dependent Vibrational Dynamics and Phonon Transport in Nanocellulose Materials

Superinsulating nanofibrillar cellulose foams have the potential to replace fossil-based insulating materials, but the development is hampered by the moisture-dependent heat transport and the lack of direct measurements of phonon transport. Here, inelastic neutron scattering is used together with wide angle X-ray scattering (WAXS) and small angle neutron scattering to relate the moisture-dependent structural modifications to the vibrational dynamics and phonon transport and scattering of cellulose nanofibrils from wood and tunicate, and wood cellulose nanocrystals (W-CNC). The moisture interacted primarily with the disordered regions in nanocellulose, and WAXS showed that the crystallinity and coherence length increased as the moisture content increased. The phonon population derived from directional-dependent phonon density of states (GDOS) increased along the cellulose chains in W-CNC between 5 and 8 wt% D2O, while the phonon population perpendicular to the chains remained relatively unaffected, suggesting that the effect of increased crystallinity and coherence length on phonon transport is compensated by the moisture-induced swelling of the foam walls. Frequency scaling in the low-energy GDOS showed that materials based on hygroscopic and semicrystalline nanocellulose falls in between the predicted behavior for solids and liquids. Phonon-engineering of hygroscopic biopolymer-based insulation materials is promoted by the insights on the moisture-dependent phonon transport.

Utilizing High X-ray Energy Photon-In Photon-Out Spectroscopies and X-ray Scattering to Experimentally Assess the Emergence of Electronic and Atomic Structure of ZnS Nanorods

The key to controlling the fabrication process of transition metal sulfide nanocrystals is to understand the reaction mechanism, especially the coordination of ligands and solvents during their synthesis. We utilize in situ high-energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) as well as in situ valence-to-core X-ray emission spectroscopy (vtc-XES) combined with density functional theory (DFT) calculations to identify the formation of a tetrahedral [Zn(OA)4]2+ and an octahedral [Zn(OA)6]2+ complex, and the ligand exchange to a tetrahedral [Zn(SOA)4]2+ complex (OA = oleylamine, OAS = oleylthioamide), during the synthesis of ZnS nanorods in oleylamine. We observe in situ the transition of the electronic structure of [Zn(SOA)4]2+ with a HOMO/LUMO gap of 5.0 eV toward an electronic band gap of 4.3 and 3.8 eV for 1.9 nm large ZnS wurtzite nanospheres and 2 × 7 nm sphalerite nanorods, respectively. Thus, we demonstrate how in situ multimodal X-ray spectroscopy and scattering studies can not only resolve structure, size, and shape during the growth and synthesis of NPs in organic solvents and at high temperature but also give direct information about their electronic structure, which is not readily accessible through other techniques.

Antisolvent controls the shape and size of anisotropic lead halide perovskite nanocrystals

Colloidal lead halide perovskite nanocrystals have potential for lighting applications due to their optical properties. Precise control of the nanocrystal dimensions and composition is a prerequisite for establishing practical applications. However, the rapid nature of their synthesis precludes a detailed understanding of the synthetic pathways, thereby limiting the optimisation. Here, we deduce the formation mechanisms of anisotropic lead halide perovskite nanocrystals, 1D nanorods and 2D nanoplatelets, by combining in situ X-ray scattering and photoluminescence spectroscopy. In both cases, emissive prolate nanoclusters form when the two precursor solutions are mixed. The ensuing antisolvent addition induces the divergent anisotropy: The intermediate nanoclusters are driven into a dense hexagonal mesophase, fusing to form nanorods. Contrastingly, nanoplatelets grow freely dispersed from dissolving nanoclusters, stacking subsequently in lamellar superstructures. Shape and size control of the nanocrystals are determined primarily by the antisolvent's dipole moment and Hansen hydrogen bonding parameter. Exploiting the interplay of antisolvent and organic ligands could enable more complex nanocrystal geometries in the future.

A new dual-thickness semi-transparent beamstop for small-angle X-ray scattering

An innovative dual-thickness semi-transparent beamstop designed to enhance the performance of small-angle X-ray scattering (SAXS) experiments is introduced. This design integrates two absorbers of differing thicknesses side by side into a single attenuator, known as a beamstop. Instead of completely stopping the direct beam, it attenuates it, allowing the SAXS detector to measure the transmitted beam through the sample. This approach achieves true synchronization in measuring both scattered and transmitted signals and effectively eliminates higher-order harmonic contributions when determining the transmission light intensity through the sample. This facilitates and optimizes signal detection and background subtraction. This contribution details the theoretical basis and practical implementation of this solution at the SAXS station on the 1W2A beamline at the Beijing Synchrotron Radiation Facility. It also anticipates its application at other SAXS stations, including that at the forthcoming High Energy Photon Source, providing an effective solution for high-precision SAXS experiments.

Bridging length scales in hard materials with ultra-small angle X-ray scattering - a critical review

Owing to their exceptional properties, hard materials such as advanced ceramics, metals and composites have enormous economic and societal value, with applications across numerous industries. Understanding their microstructural characteristics is crucial for enhancing their performance, materials development and unleashing their potential for future innovative applications. However, their microstructures are unambiguously hierarchical and typically span several length scales, from sub-ångstrom to micrometres, posing demanding challenges for their characterization, especially for in situ characterization which is critical to understanding the kinetic processes controlling microstructure formation. This review provides a comprehensive description of the rapidly developing technique of ultra-small angle X-ray scattering (USAXS), a nondestructive method for probing the nano-to-micrometre scale features of hard materials. USAXS and its complementary techniques, when developed for and applied to hard materials, offer valuable insights into their porosity, grain size, phase composition and inhomogeneities. We discuss the fundamental principles, instrumentation, advantages, challenges and global status of USAXS for hard materials. Using selected examples, we demonstrate the potential of this technique for unveiling the microstructural characteristics of hard materials and its relevance to advanced materials development and manufacturing process optimization. We also provide our perspective on the opportunities and challenges for the continued development of USAXS, including multimodal characterization, coherent scattering, time-resolved studies, machine learning and autonomous experiments. Our goal is to stimulate further implementation and exploration of USAXS techniques and inspire their broader adoption across various domains of hard materials science, thereby driving the field toward discoveries and further developments.

Polymeric Fibers with High Strength and High Toughness at Extreme Temperatures

Developing strong and simultaneously tough polymeric materials with excellent thermal stability and mechanical performance even under extreme temperatures is truly a challenge. In a disruptive progress, continuous polymeric yarns are developed with a combination of high tensile strength of (1145 ± 44) MPa and ultrahigh toughness of (350 ± 24) J g-1 and high thermomechanical properties from -196 to 200 °C. The comprehensive thermomechanical performance of this yarn surpasses that of previously developed polymeric materials and dragline spider silks. The results demonstrate that the molecular structure of polyimide (PI) with the incorporation of flexible-rigid macromolecular, hierarchically spiral-oriented fibers, and high glass transition temperature (248 °C) are keys for the yarn's notable comprehensive performance in thermomechanical properties. The materials are ideal for technical components exposed to high thermomechanical loadings, such as those encountered in spacecraft or automotive engineering for safety-critical applications.

Unveiling breast cancer metastasis through an advanced X-ray imaging approach

Breast cancer is a significant global health burden, causing a substantial number of deaths. Systemic metastatic tumour cell dissemination is a major cause of poor outcomes. Understanding the mechanisms underlying metastasis is crucial for effective interventions. Changes in the extracellular matrix play a pivotal role in breast cancer metastasis. In this work, we present an advanced multimodal X-ray computed tomography, by combining Small-angle X-ray Scattering Tensor Tomography (SAXS-TT) and X-ray Fluorescence Computed Tomography (XRF-CT). This approach likely brings out valuable information about the breast cancer metastasis cascade. Initial results from its application on a breast cancer specimen reveal the collective influence of key molecules in the metastatic mechanism, identifying a strong correlation between zinc accumulation (associated with matrix metalloproteinases MMPs) and highly oriented collagen. MMPs trigger collagen alignment, facilitating breast cancer cell intravasation, while iron accumulation, linked to angiogenesis and vascular endothelial growth factor VEGF, supports cell proliferation and metastasis. Therefore, these findings highlight the potential of the advanced multimodal X-ray computed tomography approach and pave the way for in-depth investigation of breast cancer metastasis, which may guide the development of novel therapeutic approaches and enable personalised treatment strategies, ultimately improving patient outcomes in breast cancer management.