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Sugarcane bagasse–based raw materials are predominantly used for their low cost and ease of availability of cellulosic materials for biocomposite engineering. Herein, we use cellulose derived from bagasse to form microfibrillated cellulose (MFC). Unmodified MFCs were chemically characterized using FTIR and SEM-EDX analysis and later treated with the addition of filler materials, such as glass powder, air bubbles, and activated carbon, in order to enhance material properties. Sugarcane bagasse microfibrillated cellulose with added filler materials were subsequently evaluated with respect to their mechanical, structural, and chemical properties. The MFC was synthesized via a facile microfibrillation process enabled by a kitchen blender at ambient conditions. The as-formed MFC was thoroughly characterized chemically to identify any chemical compositional variations, especially those observed as a result of filler addition. Changes in mechanical properties of MFCs in the presence of individual filler materials were evaluated using tensile testing and are reported at a nearly comparable strength of ~3.63 MPa. The addition of filler materials resulted in the improvement of MFC such that the MFC was easily drawn into pliable sheets. The increased flexibility of the MFC offers a simple strategy to create bagasse-based disposable utensils that could promote sustainable and eco-friendly commodities. [ABSTRACT FROM AUTHOR]

Pushing the limits of synthetic polymers in terms of stiffness and strength, aromatic polyamide fibers–like Kevlar®–are used for demanding applications in the form of fiber assemblies as ropes. The unique mechanical performance of aramid fiber is intimately linked to its hierarchical structure and orientation, induced during the spinning process. Surprisingly, after nearly 60 years of heavy use, very little is known about damage mechanisms and rational explanation of such high resistance. We report an experimental investigation of the fiber damage mechanisms at the single fiber scale (diameter ≅ 10 μm) with the aim to establish a link with the microstructure. Damage mechanisms and crack propagation are observed in situ for the first time and unveil a widespread damage over the entire length of the fiber in the form of a network of transverse and longitudinal cracks. These observations make it possible to draw a novel scenario of fracture that mitigates the small strain failure hypothesis. To shed light on the crucial role of microfibril cooperativity in fracture toughness, a slight twist is applied to the single fiber to promote tortuosity and frictional contacts between microfibrils. Statistical fracture analysis demonstrated the beneficial impact of such torsion on early failure events, since lowest fracture stresses are shifted to higher stresses. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a potential eco-friendly biopolymer. BC has higher crystallinity and purity compared to plant cellulose. Scientific studies on the production of BC from lactic acid bacteria (LAB) are minimal compared to other common bacteria such as Acetobacter xylinum. LAB was screened and isolated from different tissues of Mimosa pudica (medicinal plant) using MRS broth and agar as the selective medium. LAB isolates were subjected to 16S rRNA gene sequencing of all the bacterial isolates. BC was produced from all LAB isolates by incubating at 30 °C for 14 days in herbal tea medium (Strobilanthes crispus) and HS medium (control) with 130 rpm agitation. BC produced by two selected bacterial isolates was characterized using FESEM, FTIR, XRD, and TGA. Molecular analysis of the 16S rRNA gene of all the potential LAB isolates shows 99.86 - 100% identity to 16S rRNA sequences of other Lactobacillus plantarum strains. Two selected L. plantarum strains (LBM001 & LBM004) produce BC in sphere-like particles with a 1.4 to 2.2 µm diameter range of microfiber. FTIR analysis shows that BC produced by LBM001 and LBM004 have four similar cellulose regions identified in cellulose from other sources, which are O-H stretch (3400-330 cm-1), C-H stretch (2970-2800 cm-1), O-H bending (1620cm-1) and C-O-C stretch (1100-1073 cm-1). XRD analysis shows BC produced by the L. plantarum strains consists of two different XRD peaks at the 2? angle of 21.53° and 21.85° instead of a single peak (22.76°) identified in the BC produced by A. xylinum and plant cellulose. A similar TG and DTG curved pattern was detected in the BC produced by the L. plantarum strains with the BC produced by A. xylinum and plant cellulose. The LAB isolates from M. pudica have potential in BC production based on the multiple characterization studies. [ABSTRACT FROM AUTHOR]

Natural polysaccharide crystals, such as cellulose and chitin microfibrils, are considered piezoelectric thanks to the low symmetry of their crystal structures. However, the polycrystalline nature of macroscopic samples hinders the investigation of the piezoelectric properties of these crystals. β-chitin microfibrils have a specific three-dimensional orientation in the housing tube of tubeworm Lamellibrachia satsuma where all the molecular chains possess the same chain polarity. Here, we exploited this unique tissue architecture for piezoelectric characterization at the macroscopic scale. Based on direct piezoelectric measurements with varying loading direction, amplitude, and frequency, we obtained a piezoelectric coefficient close to 1 pC/N unambiguously related to the tensile coefficient of the β-chitin crystal. This study evidences experimentally for the first time the tensile piezoelectricity of materials made of crystalline polysaccharides and ultimately contributes to the development of piezoelectric materials based on abundant polysaccharides. [ABSTRACT FROM AUTHOR]

In this study, we propose a fabrication method to obtain composites of poly(vinyl alcohol) (PVA)/ionic cellulose nanofibers, in which a fiber structure is manipulated through a reconstruction of 2,2,6,6-tetramethyl-piperidinyl-1-oxyl radical (TEMPO)-oxidized cellulose nanofiber (TCNF) or the carboxymethyl cellulose nanofiber (CMCNF) heterogeneous microfibril gels using electrospinning method. The key concept is to assemble nanofibers from thin few-nanometer-scale width cellulose nanofibers (microfibrils) to thicker several-hundred-nanometer-scale width cellulose nanofibers by electrospinning insoluble microfibril-gel-dispersion in PVA solution. In the case of CMCNF, nanofibers with less-fused structures were successfully reconstructed via electrospinning. Energy-dispersive X-ray spectroscopy revealed that sodium ions exist in the fibers, where they function as counter ions of carboxylate groups of polyelectrolyte moiety of CMCNF. Thus, the obtained composites do contain both ionic cellulose nanofibers and PVA. The proposed fabrication route can be used to fabricate composites as nonwoven fabrics of polyelectrolyte nanofibers. These natural polymer based ionic fabrics will be widely useful to propose low-environmental-impact polymer actuators and active sensing elements involving the ion transport phenomena.

It is now established that crystalline cellulose is held together not just by hydrogen bonding, but also by dispersion forces and by electrostatic attraction modulated by stereoelectronic factors such as the exo-anomeric effect. The surface chains of native cellulose microfibrils differ in C6 conformation from crystalline cellulose and therefore form different hydrogen bonds, both outward and inward. Dispersion and electrostatic forces, influenced by cellulose conformation, also operate at the microfibril surface. The surface conformation depends on whether cellulose interacts with water, with the surfaces of other microfibrils or with non-cellulosic polymers. Cellulose-water binding competes with other binding interactions, so that diverse surface interactions are finely balanced in free energy, difficult to simulate, and dependent on local details of water structuring about which little is known, especially in the presence of dispersed chains of hemicellulosic or pectic polymers. An example is the influence of hydration on the aggregation of microfibrils as measured by neutron scattering, which is large for primary-wall cellulose and small for hardwood microfibrils. There are many consequent uncertainties about the surface interactions of hydrated cellulose microfibrils, for example how pectins associate with cellulose or why cellulose-xylan interfaces resist hydration. Evidence from a range of experimental technologies, alongside simulations, will be needed to resolve these uncertainties. The practical implications are wide-ranging, from the mechanism of plant growth and the mechanical resilience of wood to the development of novel, wood-based building materials. [ABSTRACT FROM AUTHOR]

In this study, we propose a fabrication method to obtain composites of poly(vinyl alcohol) (PVA)/ionic cellulose nanofibers, in which a fiber structure is manipulated through a reconstruction of 2,2,6,6-tetramethyl-piperidinyl-1-oxyl radical (TEMPO)-oxidized cellulose nanofiber (TCNF) or the carboxymethyl cellulose nanofiber (CMCNF) heterogeneous microfibril gels using electrospinning method. The key concept is to assemble nanofibers from thin few-nanometer-scale width cellulose nanofibers (microfibrils) to thicker several-hundred-nanometer-scale width cellulose nanofibers by electrospinning insoluble microfibril-gel-dispersion in PVA solution. In the case of CMCNF, nanofibers with less-fused structures were successfully reconstructed via electrospinning. Energy-dispersive X-ray spectroscopy revealed that sodium ions exist in the fibers, where they function as counter ions of carboxylate groups of polyelectrolyte moiety of CMCNF. Thus, the obtained composites do contain both ionic cellulose nanofibers and PVA. The proposed fabrication route can be used to fabricate composites as nonwoven fabrics of polyelectrolyte nanofibers. These natural polymer based ionic fabrics will be widely useful to propose low-environmental-impact polymer actuators and active sensing elements involving the ion transport phenomena. [ABSTRACT FROM AUTHOR]

Abstract Lignin-free wood has been successfully developed via a two-step chemical treatment while maintaining its inherent hierarchical structure. The first step was alcoholysis which was conducted using ethylene glycol, and whose condition was optimized by monitoring the removal of lignin using infrared spectroscopy. The second step was bleaching wherein the delignification proceeded from the surface to the core of the wood block, and finally resulted in complete decolorization. Although the wood block was free from lignin and hemicellulose as approximately confirmed by the chemical composition analysis, the 3-dimensional colorless wood block was almost unaltered, even after freeze–drying. Then, multidirectional observation was performed to investigate whether the natural hierarchical structure from anatomical- to nano-level was maintained. Optical microscopy, X-ray microcomputed tomography, X-ray diffractometry, and transmission electron microscopy demonstrated that all the stages of hierarchical structure were maintained. The lignin-free wood block has great potential for novel materials that are supported by a 3-dimensional wooden architecture. The derived lignin-free wood is also a suitable specimen that can be used to understand the formation and functionality of the anatomical structure and lignified cell wall.

The microstructure, chemical composition and mechanical strength of heterogeneous materials of mantis shrimp (Oratosquilla oratoria) saddle were studied. As the key component of the striking system, the saddle comprised two distinct layers including outer layer and inner layer. The outer layer contained blocky microtubules and exhibited compact appearance. The inner layer presented a typical periodic lamellar structure. Due to the change of the thickness of the mineralized outer layer, the organic multilamellar structure became the foundation and enhanced the connection strength (4.55 MPa) at the connect regions between the saddle and merus exoskeleton and membrane, respectively. In the process of fracture, the lamellar structure dispersed the stress effectively by the change of the crack deflection direction and the microfibrils ordered arrangement. The exploration of mantis shrimp saddle region is beneficial to understand the striking system and provided the possibility for the stable connection of heterogeneous materials in engineering fields. The microstructure, heterogeneous material connection characteristics and high mechanical strength of saddle provide bionic models for the preparation of fiber-reinforced resin composites and soft composites. [ABSTRACT FROM AUTHOR]

Type I collagen, the predominant protein of vertebrates, assembles into fibrils that orchestrate the form and function of bone, tendon, skin, and other tissues. Collagen plays roles in hemostasis, wound healing, angiogenesis, and biomineralization, and its dysfunction contributes to fibrosis, atherosclerosis, cancer metastasis, and brittle bone disease. To elucidate the type I collagen structure-function relationship, we constructed a type I collagen fibril interactome, including its functional sites and disease-associated mutations. When projected onto an X-ray diffraction model of the native collagen microfibril, data revealed a matrix interaction domain that assumes structural roles including collagen assembly, crosslinking, proteoglycan (PG) binding, and mineralization, and the cell interaction domain supporting dynamic aspects of collagen biology such as hemostasis, tissue remodeling, and cell adhesion. Our type III collagen interactome corroborates this model. We propose that in quiescent tissues, the fibril projects a structural face; however, tissue injury releases blood into the collagenous stroma, triggering exposure of the fibrils' cell and ligand binding sites crucial for tissue remodeling and regeneration. Applications of our research include discovery of anti-fibrotic antibodies and elucidating their interactions with collagen, and using insights from our angiogenesis studies and collagen structure-function model to inform the design of super-angiogenic collagens and collagen mimetics. [ABSTRACT FROM AUTHOR]

Lignin-free wood has been successfully developed via a two-step chemical treatment while maintaining its inherent hierarchical structure. The first step was alcoholysis which was conducted using ethylene glycol, and whose condition was optimized by monitoring the removal of lignin using infrared spectroscopy. The second step was bleaching wherein the delignification proceeded from the surface to the core of the wood block, and finally resulted in complete decolorization. Although the wood block was free from lignin and hemicellulose as approximately confirmed by the chemical composition analysis, the 3-dimensional colorless wood block was almost unaltered, even after freeze–drying. Then, multidirectional observation was performed to investigate whether the natural hierarchical structure from anatomical- to nano-level was maintained. Optical microscopy, X-ray microcomputed tomography, X-ray diffractometry, and transmission electron microscopy demonstrated that all the stages of hierarchical structure were maintained. The lignin-free wood block has great potential for novel materials that are supported by a 3-dimensional wooden architecture. The derived lignin-free wood is also a suitable specimen that can be used to understand the formation and functionality of the anatomical structure and lignified cell wall. [ABSTRACT FROM AUTHOR]

Periodic planewave and molecular cluster density functional theory (DFT) calculations were performed on three potential arrangements of 18 chain chain cellulose microfibrils (CMFs). To determine the most probable arrangement in plant cell walls, the molecular structure, 13C NMR chemical shifts and WAXS diffractograms resulting from the DFT model calculations were compared to experimental data. In addition, the relative potential energies of the 18-chain model CMFs were considered as evidence for the most likely arrangement. The preponderance of evidence for the CMF arrangement that is most probable in plant cell walls is a 6-layer CMF in an arrangement of 234432 glucan chains where each integer represents the number of chains in a given layer. An accurate model for the habit of the CMF in plant cell walls is necessary for further modeling of CMF interactions with other plant cell wall components and studies of cellulose degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of SiO 2 nanoparticles on collagen was explored in three forms of collagen (fibre, microfibril and monomer). • SiO 2 nanoparticles modulated collagen micorfibrillation by showing heterogeneity in diameter. • SiO 2 nanoparticles was attracted by collagen fibers without damaging fibre morphology. • Collagen triple helix was intact in the presence of SiO 2 nanoparticles. • Study provides new insights in collagen-SiO 2 nanoparticle interaction. Silica-based nanoparticles have found application in the development of biocomposites involving reconstituted collagen in tissue engineering and wound healing, and leather modification, specifically targeting collagen fibers. However, a comprehensive investigation into the interaction between collagen-silica nanoparticles and different forms of collagen using biophysical methods remains unexplored. In this study, we examined the interaction between silica (SiO 2) nanoparticles and collagen in its fiber, microfibril, and monomer forms through high-resolution scanning electron microscopy, circular dichroism, Fourier-transform infrared spectroscopy, fluorescence analysis, zeta potential measurements, and turbidity assays. Our results reveal that SiO 2 nanoparticles exhibited a non-specific attraction towards collagen fibers without disrupting their structural integrity. Interestingly, SiO 2 nanoparticles influenced the process of microfibrillation, resulting in heterogeneous fibril diameters while maintaining the natural D-periodicity. This finding is significant, as fibril size variations can impact the properties of collagen composites. Notably, the triple helical structure of collagen in its monomer form remained unaffected in the presence of SiO 2 nanoparticles, indicating that the nanoparticles did not disrupt the electrostatic interactions that stabilize the triple helix. Additionally, the increased stability of SiO 2 nanoparticles in the presence of collagen confirmed their interaction. These findings provide a promising avenue for the development of SiO 2 -based nanoparticles to enhance the stability of collagen fibers and control fiber sizes for biomaterial preparation. Moreover, this study advances the potential application of SiO 2 -based nanoparticles in leather tanning, an emerging field where nanoparticles can play a crucial role. [ABSTRACT FROM AUTHOR]

Fibrillin microfibrils are ubiquitous elements of extracellular matrix assemblies that play crucial roles in regulating the bioavailability of growth factors of the transforming growth factor beta superfamily. Recently, several "a disintegrin and metalloproteinase with thrombospondin motifs" (ADAMTS) proteins were shown to regulate fibrillin microfibril function. Among them, ADAMTS17 is the causative gene of Weill-Marchesani syndrome (WMS) and Weill-Marchesani-like syndrome, of which common symptoms are ectopia lentis and short stature. ADAMTS17 has also been linked to height variation in humans; however, the molecular mechanisms whereby ADAMTS17 regulates skeletal growth remain unknown. Here, we generated Adamts17-/- mice to examine the role of Adamts17 in skeletogenesis. Adamts17-/- mice recapitulated WMS, showing shorter long bones, brachydactyly, and thick skin. The hypertrophic zone of the growth plate in Adamts17-/- mice was shortened, with enhanced fibrillin-2 deposition, suggesting increased incorporation of fibrillin-2 into microfibrils. Comprehensive gene expression analysis of growth plates using laser microdissection and RNA sequencing indicated alteration of the bone morphogenetic protein (BMP) signaling pathway after Adamts17 knockout. Consistent with this, phospho-Smad1 levels were downregulated in the hypertrophic zone of the growth plate and in Adamts17-/- primary chondrocytes. Delayed terminal differentiation of Adamts17-/- chondrocytes, observed both in primary chondrocyte and primordial metatarsal cultures, and was prevented by BMP treatment. Our data indicated that Adamts17 is involved in skeletal formation by modulating BMP-Smad1/5/8 pathway, possibly through inhibiting the incorporation of fibrillin-2 into microfibrils. Our findings will contribute to further understanding of disease mechanisms and will facilitate the development of therapeutic interventions for WMS. [ABSTRACT FROM AUTHOR]

The origins of the unique properties of natural fibres have remained largely unresolved because of the complex interrelations between structural hierarchy, chirality and bound water. In this paper, analysis of the melting endotherms for bleached hardwood pulps indicates that the amount of non-freezing bound water (0.21 g/g) is roughly half of the amount of freezing bound water (0.42 g/g). We link this result to the two smallest constitutive units, microfibrils and their bundles, using molecular dynamics simulations at both hierarchical levels. The molecular water layers found in the simulations correspond quite accurately to the measured amount of non-freezing and freezing bound water. Disorder that results from the microfibril twist and amphiphilicity prevents co-crystallisation, leaving routes for water molecules to diffuse inside the microfibril bundle. Moreover, the simulations predict correctly the magnitude of the right-handed twist at different hierarchical levels. Significant changes in hydroxymethyl group conformations are seen during twisting that compare well with existing experimental data. Our findings go beyond earlier modelling studies in predicting the twist and structure of the microfibril bundle. [ABSTRACT FROM AUTHOR]

Abstract Collagen is a natural one-dimensional nanomaterial. Multi-walled carbon nanotubes (MWNTs) have been previously shown to interact with biomolecules and to have promising applications in reinforced biopolymers for tissue engineering and regenerative medicine. In this work, collagen/MWNT composite fibers are prepared using dry-jet wet-spinning technology. Three types of MWNTs with aspect ratios of 40, 150, and 4000 are used to investigate the effects of the MWNT aspect ratio on the properties of the composite fibers. There results show that there are strong molecular interactions between the MWNTs and collagen molecules. The mechanical properties and thermal stability of the composite fibers are significantly improved compared to those of the collagen fibers. The diameter and aspect ratio of the MWNTs are the main factors affecting the self-assembled structure of the collagen molecules, the alignment of the microfibrils, and the mechanical and thermal performance of the composite fibers. [ABSTRACT FROM AUTHOR]

The structural basis of the interdependence between moisture content and activation of cooperative dynamics in natural cellulose is explored using a solid state NMR experiment which is able to localize these motions to cellulose chains on the surface of the unitary crystallite. Making assumptions based on current knowledge of biosynthesis of cellulose and the dipolar line widths of 1H spectra in solids, it is shown that the sorption of moisture causes the activation of cooperative motion of cellulose chains on the surface of the cellulose crystallite in a manner which is related to the moisture content. An important implication for these results is that densification of cellulose and associated changes in the water sorption isotherm, is possible by structural relaxation on the nano, or unitary crystallite scale. The result is also discussed in term of the evolving and modern picture of cellulose. [ABSTRACT FROM AUTHOR]

• TEMPO-oxidized wood cellulose fibers can be converted to diverse nanocelluloses. • Cellulose nanonetworks, nanofibers, and nanocrystals dispersed in water are obtained. • Cellulose nanofibers and nanocrystals have homogeneous widths of ∼3 nm. • Cellulose nanocrystals have needle-like morphologies with aspect ratios of ∼50. • Cellulose nanofibers have aspect ratios of > 150. When wood cellulose fibers are oxidized with NaClO and catalytic amounts of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and NaBr in water at pH 10, significant amounts of sodium carboxylate groups (≤1.7 mmol/g) are introduced into the oxidized celluloses. The original fibrous morphologies and cellulose I crystal structures are unchanged by oxidation. The TEMPO-oxidized cellulose fibers can be converted to partially fibrillated nanonetworks, completely individualized cellulose nanofibers with high aspect ratios, and needle-like cellulose nanocrystals with low aspect ratios by controlling the conditions of mechanical disintegration in water. It is therefore possible to prepare diverse nanocelluloses with different morphologies and properties from the same TEMPO-oxidized cellulose fibers, for various end uses and applications. All TEMPO-oxidized nanocelluloses contain large amounts of carboxylate groups. These provide scaffolds for versatile surface modification of nanocelluloses by simple ion exchange of sodium for other metal ions and alkylammonium ions. [ABSTRACT FROM AUTHOR]

Type I collagen, the predominant protein of vertebrates, assembles into fibrils that orchestrate the form and function of bone, tendon, skin, and other tissues. Collagen plays roles in hemostasis, wound healing, angiogenesis, and biomineralization, and its dysfunction contributes to fibrosis, atherosclerosis, cancer metastasis, and brittle bone disease. To elucidate the type I collagen structure-function relationship, we constructed a type I collagen fibril interactome, including its functional sites and disease-associated mutations. When projected onto an X-ray diffraction model of the native collagen microfibril, data revealed a matrix interaction domain that assumes structural roles including collagen assembly, crosslinking, proteoglycan (PG) binding, and mineralization, and the cell interaction domain supporting dynamic aspects of collagen biology such as hemostasis, tissue remodeling, and cell adhesion. Our type III collagen interactome corroborates this model. We propose that in quiescent tissues, the fibril projects a structural face; however, tissue injury releases blood into the collagenous stroma, triggering exposure of the fibrils’ cell and ligand binding sites crucial for tissue remodeling and regeneration. Applications of our research include discovery of anti-fibrotic antibodies and elucidating their interactions with collagen, and using insights from our angiogenesis studies and collagen structure-function model to inform the design of super-angiogenic collagens and collagen mimetics.

Adhesive contact between a flat brush structure with deformable microfibrils and an elastic half space is numerically simulated. The stiffness of pillars is modeled by linear springs. The fast Fourier transform-assisted boundary element method for the contact of rigid indenters is modified to include the microfibril stiffness so that the deflection of pillars and elastic interaction to elastic foundation are coupled. In the limiting case of rigid pillars (pillar stiffness is much larger than the contact stiffness), the adhesive force is determined by the filling factor of brush, as described earlier. In the case of very soft pillars, the adhesive force is proportional to N1/4, where N is the number of pillars. The influence of relative stiffness, number and distribution of pillars on adhesive force is studied numerically. The results from both regularly and randomly distributed pillars show that the adhesive force is enhanced by splitting a compact punch into microfibrils and this effect becomes larger when the fibrils are softer.

Abstract Elastin is expressed in most tissues that require elastic recoil. The protein first appeared coincident with the closed circulatory system, and was critical for the evolutionary success of the vertebrate lineage. Elastin is expressed by multiple cell types in the lung, including mesothelial cells in the pleura, smooth muscle cells in airways and blood vessels, endothelial cells, and interstitial fibroblasts. This highly crosslinked protein associates with fibrillin-containing microfibrils to form the elastic fiber, which is the physiological structure that functions in the extracellular matrix. Elastic fibers can be woven into many different shapes depending on the mechanical needs of the tissue. In large pulmonary vessels, for example, elastin forms continuous sheets, or lamellae, that separate smooth muscle layers. Outside of the vasculature, elastic fibers form an extensive fiber network that originates in the central bronchi and inserts into the distal airspaces and visceral pleura. The fibrous cables form a looping system that encircle the alveolar ducts and terminal air spaces and ensures that applied force is transmitted equally to all parts of the lung. Normal lung function depends on proper secretion and assembly of elastin, and either inhibition of elastin fiber assembly or degradation of existing elastin results in lung dysfunction and disease. Highlights • The appearance of elastin in vertebrates was important for the advent of a closed circulatory system and the elastic lung. • In the lung, elastin is expressed in the pleura, the blood vascular system, and in the bronchi and respiratory units. • Elastin is required for normal lung development and is tightly linked with alveolar formation. • Destruction of elastin, or abnormalities in elastic fiber assembly, are major factors in emphysema and lung diseases. [ABSTRACT FROM AUTHOR]

Abstract Microfibril-associated glycoproteins 1 and 2 (MAGP-1, MAGP-2) are protein components of extracellular matrix microfibrils. These proteins interact with fibrillin, the core component of microfibrils, and impart unique biological properties that influence microfibril function in vertebrates. MAGPs bind active forms of TGFβ and BMPs and are capable of modulating Notch signaling. Mutations in MAGP-1 or MAGP-2 have been linked to thoracic aneurysms and metabolic disease in humans. MAGP-2 has also been shown to be an important biomarker in several human cancers. Mice lacking MAGP-1 or MAGP-2 have defects in multiple organ systems, which reflects the widespread distribution of microfibrils in vertebrate tissues. This review summarizes our current understanding of the function of the MAGPs and their relationship to human disease. Highlights • MAGP-1 and MAGP-2 are microfibril-associated proteins that work with fibrillin to define microfibril function. • Both MAGPs bind active forms of TGFβ and BMPs, and are capable of modulating Notch signaling. • Neither protein is required for normal development, but MAGP gene mutations lead to defects in multiple organ systems. [ABSTRACT FROM AUTHOR]

Bone is a multiscale combination of collagen molecules merged with mineral crystals. Its high rigidity and stability stem amply from its polymeric organic matrix and secondly from the connections established between interdifferent and intradifferent scale components through cross-links. Several studies have shown that the cross-links inhibition results in a reduction in strength of bone but they do not quantify the degree to which these connections contribute to the bone rigidity and toughness. This report is classified among the few works that measure the cross-links multiscale impact on the ultrastructure bone mechanical behavior. This work aims firstly to study the effect of cross-links at the molecule scale and secondly to gather from literature studies results handling with cross-links effects on the other bone ultrastructure scales in order to reveal the multiscale effect of cross-links. This study proves that cross-links increasing number improves the mechanical performance of each scale of bone ultrastructure. On the other hand, cross-links have a multiscale contribution that depends on its rank related to existing cross-links connecting the same geometries and it depends on mechanical characteristics of geometries connected. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations of cellulose regularly sample a conformational space different to the crystal structures they were initiated from, with changes to the tilt of chains, expansion of the unit cell and variation in exocyclic group conformations. Given the differences in the structures sampled the question presents itself as to whether these simulations are sampling structures that resemble cellulose in planta. To investigate this question, we have performed MD simulations on different size and shaped Iα and Iβ cellulose microfibrils with the structures generated characterized with regards to changes in expansion, chain shift along the polymerization axis, tilt, exocyclic conformation and H-bonding. Structures were then input into a quantum mechanical NMR chemical shift calculation protocol with the resulting 13C chemical shifts compared to experimental data. Chemical shifts were shown to be strongly dependent on the exocyclic group conformation with the structures of Iα simulations more closely replicating experimental data than the Iβ simulations, especially at the C4 and C6 positions which suggests that the conformational space was not being accurately represented for the Iβ microfibrils. Despite this, peak sizes based on the sampling occupancy of exocyclic conformations from unrestrained simulations were found to replicate experimental peak sizes better than simulations where exocyclic groups of interior chains were restrained to the tg conformation, suggesting that exocyclic groups have greater freedom to sample different conformations than suggested by their crystal structures. [ABSTRACT FROM AUTHOR]

Microcrystalline cellulose and Bombyx mori silk blended biocomposite films were regenerated using various imidazolium-based ionic liquids. The films were characterized to understand the effect of the inter- and intra-molecular interactions upon the morphology and thermal properties. Various techniques were implemented to investigate structural, morphological and thermal properties of the biocomposite films, including Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray scattering. Results show that the type of ionic liquid has strong influence on the structure of silk-cellulose composites that can form either amorphous or semicrystalline structures. While the thermal properties are independent of the type of cation in ionic liquids, the levels of β-sheet configuration are dependent on the type of anion, which further causes changes on the biocomposite thermal properties. The topological image provided information to support morphological effects on the varying ionic liquids and X-ray scattering allowed for insight on the role of ionic liquids on the crystallinity and the spacing differences in biocomposite films. The results have demonstrated that there is a direct relationship between the intermolecular interactions in films and the anion structure of the ionic liquids. [ABSTRACT FROM AUTHOR]

Cellulose consists of linear chains of ß-1,4-linked glucose units, which are synthesized by the cellulose synthase complex (CSC). In plants, these chains associate in an ordered manner to form the cellulose microfibrils. Both the CSC and the local environment in which the individual chains coalesce to form the cellulose microfibril determine the structure and the unique physical properties of the microfibril. There are several recent reviews that cover many aspects of cellulose biosynthesis, which include trafficking of the complex to the plasma membrane and the relationship between the movement of the CSC and the underlying cortical microtubules (Bringmann et al. 2012 Trends Plant Sci. 17, 666-674 (doi:10.1016/j.tplants.2012.06.003); Kumar & Turner 2015 Phytochemistry 112, 91-99 (doi:10.1016/j.phytochem.2014.07.009); Schneider et al. 2016 Curr. Opin. Plant Biol. 34, 9-16 (doi:10.1016/j.pbi.2016. 07.007)). In this review, we will focus on recent advances in cellulose biosynthesis in plants, with an emphasis on our current understanding of the structure of individual catalytic subunits together with the local membrane environment where cellulose synthesis occurs. We will attempt to relate this information to our current knowledge of the structure of the cellulose microfibril and propose a model in which variations in the structure of the CSC have important implications for the structure of the cellulose microfibril produced. [ABSTRACT FROM AUTHOR]

The doublet C4 peaks at ~ 85 and ~ 89 ppm in solid-state C NMR spectra of native cellulose have been attributed to signals of C4 atoms on the surface (solvent-exposed) and in the interior of microfibrils, designated as sC4 and iC4, respectively. The relative intensity ratios of sC4 and iC4 observed in NMR spectra of cellulose have been used to estimate the degree of crystallinity of cellulose and the number of glucan chains in cellulose microfibrils. However, the molecular structures of cellulose responsible for the specific surface and interior C4 peaks have not been positively confirmed. Using density functional theory (DFT) methods and structures produced from classical molecular dynamics simulations, we investigated how the following four factors affect C NMR chemical shifts in cellulose: conformations of exocyclic groups at C6 ( tg, gt and gg), HO molecules H-bonded on the surface of the microfibril, glycosidic bond angles (Φ, Ψ) and the distances between H4 and HO3 atoms. We focus on changes in the δC4 value because it is the most significant observable for the same C atom within the cellulose structure. DFT results indicate that different conformations of the exocyclic groups at C6 have the greatest influence on δC4 peak separation, while the other three factors have secondary effects that increase the spread of the calculated C4 interior and surface peaks. [ABSTRACT FROM AUTHOR]

There is increasing experimental and computational evidence that cellulose microfibrils can exist in a stable twisted form. In this study, atomistic molecular dynamics (MD) simulations are performed to investigate the importance of intrachain hydrogen bonds on the twist in cellulose microfibrils. We systematically enforce or block the formation of these intrachain hydrogen bonds by either constraining dihedral angles or manipulating charges. For the majority of simulations a consistent right handed twist is observed. The exceptions are two sets of simulations that block the O2–O6′ intrachain hydrogen bond, where no consistent twist is observed in multiple independent simulations suggesting that the O2–O6′ hydrogen bond can drive twist. However, in a further simulation where exocyclic group rotation is also blocked, right-handed twist still develops suggesting that intrachain hydrogen bonds are not necessary to drive twist in cellulose microfibrils. [ABSTRACT FROM AUTHOR]

Aims: The structural organization of collagen from mineralized tissues, such as dentin and bone, has been a topic of debate in the recent literature. Recent reports have presented novel interpretations of the complexity of collagen type I at different hierarchical levels and in different tissues. Here, we investigate the nanostructural organization of demineralized dentin collagen following the digestion of non-collagenous components with a trypsin enzyme.Materials and Methods:Dentin specimens were obtained from healthy third-molars, cut into small cubes, and polished down to 1 µm roughness. Samples were then demineralized with 10% citric acid for 2 min. Selected specimens were further treated with a solution containing 1 mg/ml trypsin for 48 hours at 37 °C (pH 7.9–9.0). Both untreated and trypsin digested samples were analyzed using SDS-PAGE, Field Emission Scanning Electron Microscopy (FE-SEM), and nanoindentation, where surface hardness and creep properties were compared before and after treatments.Results:FE-SEM images of demineralized dentin showed the banded morphology of D-periodical collagen type I, which upon enzymatic digestion with trypsin appeared to dissociate longitudinally, consistently unraveling ~20 nm structures (microfibril bundles). Such nanoscale structures, to the best of our knowledge, have not been characterized in dentin previously. Mechanical characterization via nanoindentation showed that the unraveling of such microfibril bundles affected the creep displacement and creep rate of demineralized dentin.Conclusion:In summary, our results provide novel evidence of the organization of collagen type I from dentin, which may have important implications for the interaction of dental materials with the organic dentin matrix and the mechanical properties of mineralized tissues. [ABSTRACT FROM AUTHOR]

Cellulose and silk blended biomaterial films were regenerated from ionic liquid solution and investigated to characterize and understand the effect of inter- and intra-molecular interactions upon the morphology and thermal properties. The blended films were dissolved in 1-allyl-3-methylimidazolium chloride ionic liquid, coagulated and regenerated with water. Various characterization techniques were implemented to characterize structural, morphological and thermal properties: FTIR, SEM, TGA, DSC and X-ray scattering. The results showed that the cellulose microcrystalline structure and β-sheets from the silk can be disrupted by inter- and intra-molecular hydrogen bonds forming intermediate semicrystalline or amorphous structures. The SEM showed morphological effects of such interactions that cause varying thermal degradation and glass transition temperature. The X-ray scattering confirms such findings at the molecular level, demonstrating that the cellulose microfibril diameter decreases as the silk content increases. It also shows that the β-sheets size increases as the cellulose content increases. These various techniques provide evidence that suggest the hydrogen bonds between the β-sheets and the glucose units in the cellulose chains control the thermal and structural properties of the blended films, changing the morphology and physicochemical properties. [ABSTRACT FROM AUTHOR]