Of the 7-8 silk fibers making up an orb-web only the hierarchical structural organization of semicrystalline radial fibers -composed of major ampullate silk- has been studied in detail, given its ...fascinating mechanical features. While major ampullate silk's nanofibrillar morphology is well established, knowhow on mesoscale (> 50-100 nm) assembly and its contribution to mechanical performance is limited. Much less is known on the hierarchical structural organization of other, generally less crystalline fibers contributing to an orb-webs' function. Here we show by scanning X-ray micro&nanodiffraction that two fully amorphous, fine silk fibers from the center of an orb-web have different mesoscale features. One of the fibers has a fibrillar composite structure resembling stiff egg case silk. The other fiber has a skin-core structure based on a nanofibrillar ribbon wound around a disordered core. A fraction of nanofibrils appears to have assembled into mesoscale fibrils. This fiber becomes readily attached to the coat of major ampullate silk fibers. We observe that a detached fiber has ripped out the glycoprotein skin-layer containing polyglycine II nanocrystallites. The anchoring of the fiber in the coat suggests that it could serve for strengthening the tension and cohesion of major ampullate silk fibers.
Halide perovskites are promising semiconductors for inexpensive, high-performance optoelectronics. Despite a remarkable defect tolerance compared to conventional semiconductors, perovskite thin films ...still show substantial microscale heterogeneity in key properties such as luminescence efficiency and device performance. However, the origin of the variations remains a topic of debate, and a precise understanding is critical to the rational design of defect management strategies. Through a multi-scale investigation – combining correlative synchrotron scanning X-ray diffraction and time-resolved photoluminescence measurements on the same scan area – we reveal that lattice strain is directly associated with enhanced defect concentrations and non-radiative recombination. The strain patterns have a complex heterogeneity across multiple length scales. We propose that strain arises during the film growth and crystallization and provides a driving force for defect formation. Our work sheds new light on the presence and influence of structural defects in halide perovskites, revealing new pathways to manage defects and eliminate losses.
Radiation damage limits the accuracy of macromolecular structures in X-ray crystallography. Cryogenic (cryo-) cooling reduces the global radiation damage rate and, therefore, became the method of ...choice over the past decades. The recent advent of serial crystallography, which spreads the absorbed energy over many crystals, thereby reducing damage, has rendered room temperature (RT) data collection more practical and also extendable to microcrystals, both enabling and requiring the study of specific and global radiation damage at RT. Here, we performed sequential serial raster-scanning crystallography using a microfocused synchrotron beam that allowed for the collection of two series of 40 and 90 full datasets at 2- and 1.9-Å resolution at a dose rate of 40.3 MGy/s on hen egg white lysozyme (HEWL) crystals at RT and cryotemperature, respectively. The diffraction intensity halved its initial value at average doses (D
1/2) of 0.57 and 15.3 MGy at RT and 100 K, respectively. Specific radiation damage at RT was observed at disulfide bonds but not at acidic residues, increasing and then apparently reversing, a peculiar behavior that can be modeled by accounting for differential diffraction intensity decay due to the nonuniform illumination by the X-ray beam. Specific damage to disulfide bonds is evident early on at RT and proceeds at a fivefold higher rate than global damage. The decay modeling suggests it is advisable not to exceed a dose of 0.38 MGy per dataset in static and time-resolved synchrotron crystallography experiments at RT. This rough yardstick might change for proteins other than HEWL and at resolutions other than 2 Å.
This contribution deals with the hydrothermal synthesis of the metal-organic framework aluminum trimesate, analogous to the MIL-100-type, previously reported with chromium(III) and iron(III). ...MIL-100(Al) crystallizes within a very narrow pH range (0.5−0.7) after heating a mixture of aluminum nitrate, trimethyl 1,3,5-benzenetricarboxylate (Me3btc), nitric acid, and water at 210 °C for 3.5 h. The resulting product consists of tiny octahedral shaped crystals of 2 μm size, which have been used for the atomic structure determination. It was carried out by means of single crystal using the microdiffraction setup together with microfocalized synchrotron radiation at station ID13 (ESRF, France). Solid-state NMR characterization was fully consistent with XRD structure but with higher local symmetry. The three-dimensional open framework obtained from direct methods calculations reveals the arrangement of supertetrahedral (ST) building blocks based on the MTN topology (related to the zeolite ZSM-39). Each ST motif is built up from four μ3-oxo-centered trinuclear unit (Al3O) located at each corner and linked to the four btc ligands located on each face of the tetrahedron. MIL-100 (Al) exhibits BET and Langmuir surface area of 2152(39) m2 g−1 and 2919(44) m2 g−1, respectively (pore volume: 0.82 cm3 g−1).
Abstract
Chemists aim to meet modern sustainability, health, and safety requirements by replacing conventional solvents with deep eutectic solvents (DESs). Through large melting point depressions, ...DESs may incorporate renewable solids in task-specific liquids. Yet, DES design is complicated by complex molecular interactions and a lack of comprehensive property databases. Even measuring pure component melting properties can be challenging, due to decomposition before melting. Here we overcame the decomposition of
the
quintessential DES constituent, choline chloride (ChCl). We measured its enthalpy of fusion (13.8 ± 3.0 kJ ⋅ mol) and melting point (687 ± 9 K) by fast scanning calorimetry combined with micro-XRD and high-speed optical microscopy. Our thermodynamically coherent fusion properties identify ChCl as an ionic plastic crystal and demonstrate negative deviations from ideal mixing for ChCl—contradicting previous assumptions. We hypothesise that the plastic crystal nature of ammonium salts governs their resilience to melting; pure or mixed. We show that DESs based on ionic plastic crystals can profit from (1) a low enthalpy of fusion and (2) favourable mixing. Both depress the melting point and can be altered through ion selection. Ionic plastic crystal-based DESs thus offer a platform for task-specific liquids at a broad range of temperatures and compositions.
Structuring over many length scales is a design strategy widely used in Nature to create materials with unique functional properties. We here present a comprehensive analysis of an adult sea urchin ...spine, and in revealing a complex, hierarchical structure, show how Nature fabricates a material which diffracts as a single crystal of calcite and yet fractures as a glassy material. Each spine comprises a highly oriented array of Mg-calcite nanocrystals in which amorphous regions and macromolecules are embedded. It is postulated that this mesocrystalline structure forms via the crystallization of a dense array of amorphous calcium carbonate (ACC) precursor particles. A residual surface layer of ACC and/or macromolecules remains around the nanoparticle units which creates the mesocrystal structure and contributes to the conchoidal fracture behavior. Nature's demonstration of how crystallization of an amorphous precursor phase can create a crystalline material with remarkable properties therefore provides inspiration for a novel approach to the design and synthesis of synthetic composite materials.
In contrast to synthetic materials, materials produced by organisms are formed in ambient conditions and with a limited selection of elements. Nevertheless, living organisms reveal elegant strategies ...for achieving specific functions, ranging from skeletal support to mastication, from sensors and defensive tools to optical function. Using state-of-the-art characterization techniques, we present a biostrategy for strengthening and toughening the otherwise brittle calcite optical lenses found in the brittlestar Ophiocoma wendtii. This intriguing process uses coherent nanoprecipitates to induce compressive stresses on the host matrix, functionally resembling the Guinier–Preston zones known in classical metallurgy. We believe that these calcitic nanoparticles, being rich in magnesium, segregate during or just after transformation from amorphous to crystalline phase, similarly to segregation behavior from a supersaturated quenched alloy.
High‐resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster‐scanning serial protein crystallography on micro‐ and nano‐focused ...beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi‐processing and GUI‐driven Python‐based pre‐analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster‐scanning serial micro‐ and nano‐protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high‐resolution structural data from micro‐sized crystals. Advantages of the proposed approach are its thriftiness, its handling‐free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.
Owing to their large penetration depth and high resolution, X‐rays are ideally suited to study structures and structural changes within intact biological cells. For this reason, X‐ray‐based ...techniques have been used to investigate adhesive cells on solid supports. However, these techniques cannot easily be transferred to the investigation of suspended cells in flow. Here, an X‐ray compatible microfluidic device that serves as a sample delivery system and measurement environment for such studies is presented. As a proof of concept, the microfluidic device is applied to investigate chemically fixed bovine red blood cells by small‐angle X‐ray scattering (SAXS). A very good agreement is found between in‐flow and static SAXS data. Moreover, the data are fitted with a hard‐sphere model and screened Coulomb interactions to obtain the radius of the protein hemoglobin within the cells. Thus, the utility of this device for studying suspended cells with SAXS in continuous flow is demonstrated.
Microfluidics enables us to measure whole mammalian cells in continuous flow by small‐angle X‐ray scattering.
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