Revealing the Solution Conformation and Hydration Structure of Type I Tropocollagen Using X-ray Scattering and Molecular Dynamics Simulation.

Hydration plays a crucial role in regulating the dispersion behavior of biomolecules in water, particularly in how pH-sensitive hydration water network forms around proteins. This study explores the conformation and hydration structure of Type-I tropocollagen using small- and wide-angle X-ray scattering (SWAXS) and molecular dynamics (MD) simulations. The results reveal that tropocollagen exhibits a significant softening conformation in solution, transitioning from its rod-like structure in tissues to a worm-like conformation, characterized by a reduced radius of gyration of 50 nm and a persistent length of 34 nm.

Molecular dynamics simulations and X-ray scattering show the κ-carrageenan disorder-to-order transition to be the formation of double-helices.

Recent molecular dynamics simulations, verified experimentally by solution-state x-ray scattering experiments, have found that κ-carrageenan chains contain helical secondary structure, akin to that found in the solid-state, even in aqueous solution. Furthermore, upon the addition of ions to single chains the simulations found no evidence that any conformational transitions take place. These findings challenge the long-held assumption that the so-called disorder-to-order transition in carrageenan systems involves a uni-molecular 'coil-to-helix transition'.

Hydrogen bonding dissipating hydrogels: The influence of network structure design on structure-property relationships.

Hydrogels made with semi-interpenetrating networks of the oligomerized polyphenol tannic acid, and poly(acrylamide), exhibit high stiffness and toughness. However, the structure property relationships that give rise to enhanced mechanical properties is not well understood. Herein, we systematically investigate the hydrogels using small angle X-ray scattering and small and Ultra-small angle neutron scattering within a wide length scale range (1 nm to 20 µm), polarized optical microscopy, and rheology.

X-ray scattering and molecular dynamics simulations reveal the secondary structure of κ-carrageenan in the solution state.

The solution state structure of κ-carrageenan is typically described as a 'random coil', to indicate a lack of defined secondary structure elements. From this starting point the assignment of an optical-rotation-detected change that follows the introduction of particular ions to such solutions as a 'coil-to-helix transition' seems unambiguous, and thus the canonical description of this important biopolymer's gelling behaviour was born. However, the notion that κ-carrageenan exists in solution as a random coil, devoid of secondary structure, has been questioned a number of times previously in the literature, particularly by the molecular modelling and NMR communities.

Effect of Dialdehyde Carboxymethyl Cellulose Cross-Linking on the Porous Structure of the Collagen Matrix.

Porous structures are essential for some collagen-based biomaterials and can be regulated by crosslinkers. Herein, dialdehyde carboxymethyl cellulose (DCMC) crosslinkers with similar size but different aldehyde group contents were prepared through periodate oxidation of sodium carboxymethyl cellulose with varying degrees of substitution (DS). They can penetrate into the hierarchy of fibril and form inter-molecular and intra-fibril cross-linking within the collagen matrix due to their nanoscale sizes and reactive aldehyde groups.

Calcium peroxide aids tyramine-alginate gel to crosslink with tyrosinase for efficient cartilage repair.

The innate cartilage extracellular matrix is avascular and plays a vital role in innate chondrocytes. Recapping the crucial components of the extracellular matrix in engineered organs via polymeric gels and bioinspired approaches is promising for improving the regenerative aptitude of encapsulated cartilage/chondrocytes. Conventional gel formation techniques for polymeric materials rely on employing oxidative crosslinking, which is constrained in this avascular environment.

Supramolecular Assembly of Multifunctional Collagen Nanocomposite Film via Polyphenol-Coordinated Clay Nanoplatelets.

Functional bionanocomposites have evoked immense research interests in many fields including biomedicine, food packaging, and environmental applications. Supramolecular self-assembled bionanocomposite materials fabricated by biopolymers and two-dimensional (2D) nanomaterials have particularly emerged as a compelling material due to their biodegradable nature, hierarchical structures, and designable multifunctions. However, construction of these materials with tunable properties has been still challenging.

Kinetics and Mechanism of In Situ Metallization of Bulk DNA Films.

DNA-templated metallization is broadly investigated in the fabrication of metallic structures by virtue of the unique DNA-metal ion interaction. However, current DNA-templated synthesis is primarily carried out based on pure DNA in an aqueous solution. In this study, we present in situ synthesis of metallic structures in a natural DNA complex bulk film by UV light irradiation, where the growth of silver particles is resolved by in situ time-resolved small-angle X-ray scattering and dielectric spectroscopy.

Cold-atmospheric plasma augments functionalities of hybrid polymeric carriers regenerating chronic wounds: In vivo experiments.

The skin possesses an epithelial barrier. Delivering growth factors to deeper wounds is usually rather challenging, and these typically restrict the therapeutic efficacy for chronic wound healing. Efficient healing of chronic wounds also requires abundant blood flow.

Cold atmospheric plasma physically reinforced substances of platelets-laden photothermal-responsive methylcellulose complex restores burn wounds.

Patients with irregular, huge burn wounds require time-consuming healing. The skin has an epithelial barrier mechanism. Hence, the penetration and retention of therapeutics across the skin to deep lesion is generally quite difficult and these usually constrain the delivery/therapeutic efficacies for wound healing.

Superhelical DNA liquid crystals from dendrimer-induced DNA compaction.

Electrostatic compaction of double stranded DNA induced by a positively charged poly(amidoamine) (PAMAM) dendrimer of generation four (G4) was found to produce two unique types of DNA mesophases, in which the DNA bent into superhelices packed in a tetragonal or hexagonal lattice. The structure formed at a lower dendrimer charge density was three-dimensionally (3D) ordered, as characterized by the P422 space group with a 4 screw axis in a tetragonal arrangement, showing that the weakly bent DNA superhelices with a pitch length of ca. 5.

Hierarchical structure in poly(N-vinyl carbazole)/FeO nanocomposites and the relevant magnetic coercivity.

In this study, we report the dependence of the nanoparticle dispersion on the zero-conversion initiator efficiency in the nanocomposites formed by poly(N-vinyl carbazole) (PNVK) and acrylic acid-modified iron oxide (AA-FeO) nanoparticles via free radical solution polymerization of the precursor solution, that is, a thorough mixture of 28.5 wt% AA-FeO nanoparticles and the N-vinyl carbazole (NVK) monomer with the solvent dimethylformamide and azobisisobutyronitrile as an initiator. Here three different types of the dispersion state of AA-FeO nanoparticles in the PNVK matrix have been distinguished by a combined approach of transmission electron microscopy and small-angle X-ray scattering coupled with real-space models of the nanoparticle assemblies.

Hierarchical Incorporation of Surface-Functionalized Laponite Clay Nanoplatelets with Type I Collagen Matrix.

Unraveling the interaction mechanisms of type I collagen with various inorganic nanoparticles is of pivotal importance to construct collagen-based bionanocomposites with hierarchical structures for biomedical, pharmaceutical, and other industrial applications. In this study, synthetic two-dimensional Laponite nanoplatelets (LAP NPs) are surface-functionalized with tetrakis(hydroxymethyl) phosphonium sulfate (THPS) for reinforcing their incorporation with type I collagen matrix by focusing on the influences of the interactions on the hierarchical structures of the collagen. Our results indicate that the LAP NPs can be successfully surface-functionalized with THPS via covalent bonds between the amine-functionalized NPs and the hydroxymethyl groups of THPS.

Anion-regulated binding selectivity of Cr(III) in collagen.

We present a mechanism for the selectivity of covalent/electrostatic binding of the Cr(III) ion to collagen, mediated by the kosmotropicity of the anions. Although a change in the long-range ordered structure of collagen is observed after covalent binding (Cr(III)-OOC) in the presence of SO at pH 4.5, the ν (COO ) band remains intense, suggesting a relatively lower propensity for the Cr(III) to bind covalently instead of electrostatically through Cr(H O) .

In situ structural studies during denaturation of natural and synthetically crosslinked collagen using synchrotron SAXS.

Collagen is an important biomacromolecule, making up the majority of the extracellular matrix in animal tissues. Naturally occurring crosslinks in collagen stabilize its intermolecular structure in vivo, whereas chemical treatments for introducing synthetic crosslinks are often carried out ex vivo to improve the physical properties or heat stability of the collagen fibres for applications in biomaterials or leather production. Effective protection of intrinsic natural crosslinks as well as allowing them to contribute to collagen stability together with synthetic crosslinks can reduce the need for chemical treatments.

Structure of DNA-PAMAM Dendrimer Complexes Studied Using Small-angle Scattering Techniques.

Gene therapy is one of the most important developments for modern medicine. As such methods for the compaction and delivery of nucleic acids bearing therapeutic sequences is essential. The quest for non-viral carriers of nucleic acids has produced a number of possible candidates with dendrimer being among the most promising.

Resolving solution conformations of the model semi-flexible polyelectrolyte homogalacturonan using molecular dynamics simulations and small-angle x-ray scattering.

The conformation of polyelectrolytes in the solution state has long been of interest in polymer science. Herein we utilize all atom molecular dynamics simulations (MD) and small-angle x-ray scattering experiments (SAXS) to elucidate the molecular structure of the model polyelectrolyte homogalacturonan. Several degrees of polymerization were studied and in addition partial methylesterification of the otherwise charge-carrying carboxyl groups was used in order to generate samples with varying intra-chain charge distributions.

Structural Analysis of Polysaccharide Networks by Transmission Electron Microscopy: Comparison with Small-Angle X-ray Scattering.

Polysaccharide gels assembled from the anionic biopolymers pectin and carrageenan have been studied using transmission electron microscopy (TEM). Gels were formed in several different ways: for pectin, hydrogen bonding was used to form junction zones between strands, whereas for carrageenan systems, several different ion types were used to form ionotropic networks. Using this approach, several distinct network architectures were realized.

Controlling gelation with sequence: Towards programmable peptide hydrogels.

Unlabelled: The self-assembling peptide IKHLSVN, inspired by inspection of a protein-protein interface, has previously been reported as one of a new class of bio-inspired peptides. Here the peptide, dubbed littleSven, and modifications designed to probe the resilience of the sequence to self-assembly, is characterised. Although the parent peptide did not form a hydrogel, small modifications to the sequence (one side chain or an N-terminus modification) led to hydrogels with properties (eg.

Zooming in: Structural Investigations of Rheologically Characterized Hydrogen-Bonded Low-Methoxyl Pectin Networks.

Self-assembled hydrogen-bonded networks of the polysaccharide pectin, a mechanically functional component of plant cell walls, have been of recent interest as biomimetic exemplars of physical gels, and the microrheological and strain-stiffening behaviors have been previously investigated. Despite this detailed rheological characterization of preformed gels, little is known about the fundamental arrangement of the polymers into cross-linking junction zones, the size of these bonded regions, and the resultant network architecture in these hydrogen-bonded materials, especially in contrast to the plethora of such information available for their well-known calcium-assembled counterparts. In this work, in concert with pertinent rheological measurements, an in-depth structural study of the hydrogen-bond-mediated gelation of pectins is provided.

Internal stress drives slow glassy dynamics and quake-like behaviour in ionotropic pectin gels.

Frustrated, out-of-equilibrium materials have been of considerable interest for some time and continue to be some of the least understood materials. Recent measurements have shown that many gelled biopolymer materials display slow dynamics on timescales greater than one second, that are not accessible with typical methods, and are characteristic of glassy trapped systems. In this study we have controlled the fine structure of the anionic polysaccharide pectin in order to construct a series of ionotropic gels having differing binding energies between the constituent chains, in an attempt to further understand the slow dynamical processes occurring.

Determination of villous rigidity in the distal ileum of the possum (Trichosurus vulpecula).

We investigated the passive mechanical properties of villi in ex vivo preparations of sections of the wall of the distal ileum from the brushtail possum (Trichosurus vulpecula) by using a flow cell to impose physiological and supra-physiological levels of shear stress on the tips of villi. We directly determined the stress applied from the magnitude of the local velocities in the stress inducing flow and additionally mapped the patterns of flow around isolated villi by tracking the trajectories of introduced 3 µm microbeads with bright field micro particle image velocimetry (mPIV). Ileal villi were relatively rigid along their entire length (mean 550 µm), and exhibited no noticeable bending even at flow rates that exceeded calculated normal physiological shear stress (>0.