Supercoiled protein motifs: the collagen triple-helix and the alpha-helical coiled coil

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. The SWAXS-supported MD calculations further establish a hydration water network characterized by a 2.8 Å free-water exclusion zone where water molecules are largely hydrogen-bonded to the densely distributed polar groups on the tropocollagen surfaces. These first-layer water molecules are bridged by outer water molecules extending up to 4 Å from the protein surfaces, forming a major hydration shell that encapsulates the protein.

Unraveling the role of integrating signal peptides into natural collagen on modulating cancer cell adhesion

The signal peptides GVMGFO and GFOGER exhibit differential binding affinities towards Michigan Cancer Foundation-7 (MCF-7) breast cancer cells and HT-1080 human fibrosarcoma cells, respectively, which in turn modulate the cell adhesion properties of natural collagen. GVMGFO demonstrates a more potent interaction with discoidin domain receptor 1(DDR1)-expressing MCF-7 cells, whereas GFOGER preferentially binds to the integrin α2β1 present on HT-1080 cells. The integration of GVMGFO into natural collagen through direct doping or crosslinking markedly enhances its association with MCF-7 cells, especially when optimal peptide concentrations and blending ratios are utilized, indicating a synergistic effect. This augmented adhesion is attributed to specific binding at the DDR1-collagen interface, facilitated by a constellation of amino acids within the collagen scaffold engaging with the DDR1 discoidin (DS) domain through polar interactions and hydrogen bonding. Conversely, the incorporation of GFOGER into natural collagen through co-assembling or crosslinking leads to a progressive increase in adherence to HT-1080 cells, as evidenced by the peptide's affinity for integrin α2β1. These findings advance the design of collagen-based biomaterials for targeted cellular interactions in the medical, pharmaceutical, and enhance our understanding of the molecular mechanisms governing peptide-collagen mediated cell adhesion processes.

Constructing networks for comparison of collagen types

Collagens are structural proteins that are predominantly found in the extracellular matrix of multicellular animals, where they are mainly responsible for the stability and structural integrity of various tissues. All collagens contain polypeptide strands (α-chains). There are several types of collagens, some of which differ significantly in form, function, and tissue specificity. Because of their importance in clinical research, they are grouped into subdivisions, the so-called collagen families, and their sequences are often analysed. However, problems arise with highly homologous sequence segments. To increase the accuracy of collagen classification and prediction of their functions, the structure of these collagens and their expression in different tissues could result in a better focus on sequence segments of interest. Here, we analyse collagen families with different levels of conservation. As a result, clusters with high interconnectivity can be found, such as the fibrillar collagens, the COL4 network-forming collagens, and the COL9 FACITs. Furthermore, a large cluster between network-forming, FACIT, and COL28a1 α-chains is formed with COL6a3 as a major hub node. The formation of clusters also signifies, why it is important to always analyse the α-chains and why structural changes can have a wide range of effects on the body.

Oral Administration of Protease-Soluble Chicken Type II Collagen Ameliorates Anterior Cruciate Ligament Transection-Induced Osteoarthritis in Rats

This study investigated whether oral supplementation with protease-soluble chicken type II collagen (PSCC-II) mitigates the progression of anterior cruciate ligament transection (ACLT)-induced osteoarthritis (OA) in rats. Eight-week-old male Wistar rats were randomly assigned to the following groups: control, sham, ACLT, group A (ACLT + pepsin-soluble collagen type II collagen (C-II) with type I collagen), group B (ACLT + Amano M-soluble C-II with type I collagen), group C (ACLT + high-dose Amano M-soluble C-II with type I collagen), and group D (ACLT + unproteolyzed C-II). Various methods were employed to analyze the knee joint: nociceptive tests, microcomputed tomography, histopathology, and immunohistochemistry. Rats treated with any form of C-II had significant reductions in pain sensitivity and cartilage degradation. Groups that received PSCC-II treatment effectively mitigated the ACLT-induced effects of OA concerning cancellous bone volume, trabecular number, and trabecular separation compared with the ACLT alone group. Furthermore, PSCC-II and unproteolyzed C-II suppressed ACLT-induced effects, such as the downregulation of C-II and upregulation of matrix metalloproteinase-13, tumor necrosis factor-α, and interleukin-1β. These results indicate that PSCC-II treatment retains the protective effects of traditional undenatured C-II and provide superior benefits for OA management. These benefits encompass pain relief, anti-inflammatory effects, and the protection of cartilage and cancellous bone.

The investigation of batch-to-batch variabilities in the composition of isolates from fish and mammalian species using different protocols

The aim of this study was to investigate batch-to-batch inconsistencies in the processing of pig and fish collagen isolates processed using two protocols that differed in terms of the acetic acid concentrations applied and the pre- and post-extraction steps, and which were previously tested in our laboratory with the intention of preserving the biological structures and functions of the collagen isolates for biomedical purposes. Both the major and minor components such as the amino acids, lipids, water, glycosaminoglycan and ash contents and elemental content, as well as the structure and morphology of the raw sources and the resulting batches of isolates were subsequently examined in detail applying standardized analytical methods including high perfomance liquid chromatography, ultraviolet-visible and infrared spectrometry, polyacrylamide gel electrophoresis, energy dispersive spectroscopy and scanning electron microscopy. All the fish isolates provided severalfold higher yields (8-45 wt%) than did the pig isolates (3-9 wt%). In addition, the variability of the fish isolate yields (the coefficient of variation for processing A: 16.4-32.9 % and B: 6.8-17.4 %) was significantly lower (p ≤ 0.05, n = 5) than that of the pig isolates (A: 27.7-69.8 %; B: 35.3-87.9 %). In general, the fish skin batches had significantly higher protein contents (˃60 wt%) and lower lipid contents (<10 wt%) than the pig skin batches (<55 wt% protein and up to 66 wt% lipid). In addition, the fish skin batches did not differ significantly in terms of their composition applying the same processing method, whereas the pig skin batches exhibited considerable variations in terms of their compositions, particularly regarding the protein and lipid contents. It can be stated that, concerning the fish isolates, processing B was, in most cases, slightly more efficient and reproducible than processing A. However, concerning the pig isolates, although processing A appeared to be more efficient than processing B in terms of the yield, it resulted in the production of isolates that contained a certain level of contaminants. The study provides a comprehensive discussion on the suitability of the processing protocol in terms of producing batches of reproducible quality according to the specific type of biomaterial processed from different animal species.

An overview of the material science and knowledge of nanomedicine, bioscaffolds, and tissue engineering for tendon restoration

Tendon wounds are a worldwide health issue affecting millions of people annually. Due to the characteristics of tendons, their natural restoration is a complicated and lengthy process. With the advancement of bioengineering, biomaterials, and cell biology, a new science, tissue engineering, has developed. In this field, numerous ways have been offered. As increasingly intricate and natural structures resembling tendons are produced, the results are encouraging. This study highlights the nature of the tendon and the standard cures that have thus far been utilized. Then, a comparison is made between the many tendon tissue engineering methodologies proposed to date, concentrating on the ingredients required to gain the structures that enable appropriate tendon renewal: cells, growth factors, scaffolds, and scaffold formation methods. The analysis of all these factors enables a global understanding of the impact of each component employed in tendon restoration, thereby shedding light on potential future approaches involving the creation of novel combinations of materials, cells, designs, and bioactive molecules for the restoration of a functional tendon.

A novel peptide isolated from Catla skin collagen acts as a self-assembling scaffold promoting nucleation of calcium-deficient hydroxyapatite nanocrystals

Catla collagen hydrolysate (CH) was fractionated by chromatography and each fraction was subjected to HA nucleation, with the resultant HA-fraction composites being scored based on the structural and functional group of the HA formed. The process was repeated till a single peptide with augmented HA nucleation capacity was obtained. The peptide (4.6 kDa), exhibited high solubility, existed in polyproline-II conformation and displayed a dynamic yet stable hierarchical self-assembling property. The 3D modelling of the peptide revealed multiple calcium and phosphate binding sites and a high propensity to self-assemble. Structural analysis of the peptide-HA crystals revealed characteristic diffraction planes of HA with mineralization following the (002) plane, retention of the self-assembled hierarchy of the peptide and intense ionic interactions between carboxyl groups and calcium. The peptide-HA composite crystals were mostly of 25-40 nm dimensions and displayed 79% mineralization, 92% crystallinity, 39.25% porosity, 12GPa Young's modulus and enhanced stability in physiological pH. Cells grown on peptide-HA depicted faster proliferation rates and higher levels of osteogenic markers. It was concluded that the prerequisite for HA nucleation by a peptide included: a conserved sequence with a unique charge topology allowing calcium chelation and its ability to form a dynamic self-assembled hierarchy for crystal propagation.

Advanced strategies for constructing interfacial tissues of bone and tendon/ligament

Enthesis, the interfacial tissue between a tendon/ligament and bone, exhibits a complex histological transition from soft to hard tissue, which significantly complicates its repair and regeneration after injury. Because traditional surgical treatments for enthesis injury are not satisfactory, tissue engineering has emerged as a strategy for improving treatment success. Rapid advances in enthesis tissue engineering have led to the development of several strategies for promoting enthesis tissue regeneration, including biological scaffolds, cells, growth factors, and biophysical modulation. In this review, we discuss recent advances in enthesis tissue engineering, particularly the use of biological scaffolds, as well as perspectives on the future directions in enthesis tissue engineering.

Peptide-Based Supramolecular Hydrogels as Drug Delivery Agents: Recent Advances

Supramolecular peptide hydrogels have many important applications in biomedicine, including drug delivery applications for the sustained release of therapeutic molecules. Targeted and selective drug administration is often preferential to systemic drug delivery, as it can allow reduced doses and can avoid the toxicity and side-effects caused by off-target binding. New discoveries are continually being reported in this rapidly developing field. In this review, we report the latest developments in supramolecular peptide-based hydrogels for drug delivery, focusing primarily on discoveries that have been reported in the last four years (2018-present). We address clinical points, such as peptide self-assembly and drug release, mechanical properties in drug delivery, peptide functionalization, bioadhesive properties and drug delivery enhancement strategies, drug release profiles, and different hydrogel matrices for anticancer drug loading and release.

Fluorinated Protein and Peptide Materials for Biomedical Applications

Fluorination represents one of the most powerful modern design strategies to impart biomacromolecules with unique functionality, empowering them for widespread application in the biomedical realm. However, the properties of fluorinated protein materials remain unpredictable due to the heavy context-dependency of the surrounding atoms influenced by fluorine’s strong electron-withdrawing tendencies. This review aims to discern patterns and elucidate design principles governing the biochemical synthesis and rational installation of fluorine into protein and peptide sequences for diverse biomedical applications. Several case studies are presented to deconvolute the overgeneralized fluorous stabilization effect and critically examine the duplicitous nature of the resultant enhanced chemical and thermostability as it applies to use as biomimetic therapeutics, drug delivery vehicles, and bioimaging modalities.

Synthetic Collagen-like Polymer That Undergoes a Sol–Gel Transition Triggered by O–N Acyl Migration at Physiological pH

We previously reported an artificial collagen gel that can be used as a cell-culture substrate by end-to-end cross-linking of collagen-like triple-helical peptides via disulfide bonds. However, the gel had to be formed a priori by polymerizing the peptide in an acidic solution containing dimethyl sulfoxide for several days, which prevented its use as an injectable gel or three-dimensional (3D) scaffold for cell culture. In this study, we developed a collagen-like peptide polymer by incorporating an O–N acyl migration-triggered triple helix formation mechanism into a collagen-like peptide, which formed a gel within 10 min. We demonstrated that the collagen-like peptide polymer can be used as a 3D cell scaffold and that the 3D structure formation of cells can be controlled by collagen-derived bioactive sequences introduced into the peptide sequence.

Varying Synthesis Conditions and Comprehensive Characterization of Fluorine-Doped Hydroxyapatite Nanocrystals in a Simulated Body Fluid

Bone supports animal bodies, is the place where blood is produced, and is essential for the immune system, among other important functions. The dominant inorganic component in bone is hydroxyapatite (Hap), the structure and dynamics of which still pose many unsolved puzzles. An updated understanding of HAp is of great significance to osteology, dentistry, and the development of artificial bone and other biomaterials. In this work, HAp nanoparticles were synthesized with the wet chemical precipitation method and their structure and morphologies were controlled by varying pH and adding fluoride ions by two different routes: (1) fluoride ions were added during synthesis, and (2) fluoride ions were introduced after the samples were synthesized by soaking the samples in solutions with fluoride ions. XRD and HRTEM were employed to confirm the composition and structure, while various multinuclear (1H, 19F, 31P) solid-state nuclear magnetic resonance (NMR) methods including 1D single pulse, cross-polarization under magic-angle spinning (CPMAS), and 2D heteronuclear correlation (HETCOR) were used to characterize the structure, morphology, and dynamics, validating the general core-shell morphology in these F-HAp samples. It was found that all hydroxide ions were substituted when the fluoride ion concentration was above 0.005 M. An NMR peak corresponding to water structure emerged and the bulk water peak was shifted upfield, indicating that fluoride substitution modifies both the crystalline core and the amorphous shell of F-HAp nanoparticles. With the second route of fluoride substitution, increases in soaking time or fluoride ion concentration could increase fluoride substitution in HAp, but could not achieve complete substitution. Finally, with 1H-31P CPMAS and HETCOR, it was established that there are two types of phosphorous, one in the crystalline core (PO43−) and the other in the amorphous shell (HPO42−). These results are valuable for clarifying the fluoride substitution mechanism in HAp in biomaterials or in organisms, and provide insights for developing next generation replacement materials for bone, tooth, or coating films, drug delivery systems, etc.

Protein Based Biomaterials for Therapeutic and Diagnostic Applications

Proteins are some of the most versatile and studied macromolecules with extensive biomedical applications. The natural and biological origin of proteins offer such materials several advantages over their synthetic counterparts, such as innate bioactivity, recognition by cells and reduced immunogenic potential. Furthermore, proteins can be easily functionalized by altering their primary amino acid sequence and can often be further self-assembled into higher order structures either spontaneously or under specific environmental conditions. This review will feature the recent advances in protein-based biomaterials in the delivery of therapeutic cargo such as small molecules, genetic material, proteins, and cells. First, we will discuss the ways in which secondary structural motifs, the building blocks of more complex proteins, have unique properties that enable them to be useful for therapeutic delivery. Next, supramolecular assemblies, such as fibers, nanoparticles, and hydrogels, made from these building blocks that are engineered to behave in a cohesive manner, are discussed. Finally, we will cover additional modifications to protein materials that impart environmental responsiveness to materials. This includes the emerging field of protein molecular robots, and relatedly, protein-based theranostic materials that combine therapeutic potential with modern imaging modalities, including near-infrared fluorescence spectroscopy (NIRF), single-photo emission computed tomography/computed tomography (SPECT/CT), positron emission tomography (PET), magnetic resonance imaging (MRI), and ultrasound/photoacoustic imaging (US/PAI).

Chirality Bias Tissue Homeostasis by Manipulating Immunological Response

The physiological chirality of extracellular environments is substantially affected by pathological diseases. However, how this stereochemical variation drives host immunity remains poorly understood. Here, it is reported that pathology-mimetic M-nanofibrils-but not physiology-mimetic P-nanofibrils-act as a defense mechanism that helps to restore tissue homeostasis by manipulating immunological response. Quantitative multi-omics in vivo and in vitro shows that M-nanofibrils significantly inhibit inflammation and promote tissue regeneration by upregulating M2 macrophage polarization and downstream immune signaling compared with P-nanofibrils. Molecular analysis and theoretical simulation demonstrate that M-chirality displays higher stereo-affinity to cellular binding, which induces higher cellular contractile stress and activates mechanosensitive ion channel PIEZOl to conduct Ca²⁺ influx. In turn, the nuclear transfer of STAT is biased by Ca²⁺ influx to promote M2 polarization. These findings underscore the structural mechanisms of disease, providing design basis for immunotherapy with bionic functional materials.

Supramolecular Nanofibers from Collagen-Mimetic Peptides Bearing Various Aromatic Groups at N-Termini via Hierarchical Self-Assembly

Self-assembly of artificial peptides has been widely studied for constructing nanostructured materials, with numerous potential applications in the nanobiotechnology field. Herein, we report the synthesis and hierarchical self-assembly of collagen-mimetic peptides (CMPs) bearing various aromatic groups at the N-termini, including 2-naphthyl, 1-naphtyl, anthracenyl, and pyrenyl groups, into nanofibers. The CMPs (R-(GPO)n: n > 4) formed a triple helix structure in water at 4 °C, as confirmed via CD analyses, and their conformations were more stable with increasing hydrophobicity of the terminal aromatic group and peptide chain length. The resulting pre-organized triple helical CMPs showed diverse self-assembly into highly ordered nanofibers, reflecting their slight differences in hydrophobic/hydrophilic balance and configuration of aromatic templates. TEM analysis demonstrated that 2Np-CMPn (n = 6 and 7) and Py-CMP6 provided well-developed natural collagen-like nanofibers and An-CMPn (n = 5-7) self-assembled into rod-like micelle fibers. On the other hand, 2Np-CMP5 and 1Np-CMP6 were unable to form nanofibers under the same conditions. Furthermore, the Py-CMP6 nanofiber was found to encapsulate a guest hydrophobic molecule, Nile red, and exhibited unique emission behavior based on the specific nanostructure. In addition to the ability of CMPs to bind small molecules, their controlled self-assembly enables their versatile utilization in drug delivery and wavelength-conversion nanomaterials.

Tendon tissue engineering: Cells, growth factors, scaffolds and production techniques

Tendon injuries are a global health problem that affects millions of people annually. The properties of tendons make their natural rehabilitation a very complex and long-lasting process. Thanks to the development of the fields of biomaterials, bioengineering and cell biology, a new discipline has emerged, tissue engineering. Within this discipline, diverse approaches have been proposed. The obtained results turn out to be promising, as increasingly more complex and natural tendon-like structures are obtained. In this review, the nature of the tendon and the conventional treatments that have been applied so far are underlined. Then, a comparison between the different tendon tissue engineering approaches that have been proposed to date is made, focusing on each of the elements necessary to obtain the structures that allow adequate regeneration of the tendon: growth factors, cells, scaffolds and techniques for scaffold development. The analysis of all these aspects allows understanding, in a global way, the effect that each element used in the regeneration of the tendon has and, thus, clarify the possible future approaches by making new combinations of materials, designs, cells and bioactive molecules to achieve a personalized regeneration of a functional tendon.

Precise control of synthetic hydrogel network structure via linear, independent synthesis-swelling relationships

Hydrogel physical properties are tuned by altering synthesis conditions such as initial polymer concentration and polymer-cross-linker stoichiometric ratios. Traditionally, differences in hydrogel synthesis schemes, such as end-linked poly(ethylene glycol) diacrylate hydrogels and cross-linked poly(vinyl alcohol) hydrogels, limit structural comparison between hydrogels. In this study, we use generalized synthesis variables for hydrogels that emphasize how changes in formulation affect the resulting network structure. We identify two independent linear correlations between these synthesis variables and swelling behavior. Analysis through recently updated swollen polymer network models suggests that synthesis-swelling correlations can be used to make a priori predictions of the stiffness and solute diffusivity characteristics of synthetic hydrogels. The same experiments and analyses performed on methacrylamide-modified gelatin hydrogels demonstrate that complex biopolymer structures disrupt the linear synthesis-swelling correlations. These studies provide insight into the control of hydrogel physical properties through structural design and can be used to implement and optimize biomedically relevant hydrogels.

Peptide Nanomaterials for Drug Delivery Applications

Self-assembled peptides have been shown to form well-defined nanostructures which display outstanding characteristics for many biomedical applications and especially in controlled drug delivery. Such biomaterials are becoming increasingly popular due to routine, standardized methods of synthesis, high biocompatibility, biodegradability and ease of upscale. Moreover, one can modify the structure at the molecular level to form various nanostructures with a wide range of applications in the field of medicine. Through environmental modifications such as changes in pH and ionic strength and the introduction of enzymes or light, it is possible to trigger self-assembly and design a host of different self-assembled nanostructures. The resulting nanostructures include nanotubes, nanofibers, hydrogels and nanovesicles which all display a diverse range of physico-chemical and mechanical properties. Depending on their design, peptide self-assembling nanostructures can be manufactured with improved biocompatibility and in vivo stability and the ability to encapsulate drugs with the capacity for sustained drug delivery. These molecules can act as carriers for drug molecules to ferry cargo intracellularly and respond to stimuli changes for both hydrophilic and hydrophobic drugs. This review explores the types of self-assembling nanostructures, the effects of external stimuli on and the mechanisms behind the assembly process, and applications for such technology in drug delivery.

Binding mechanism of a de novo coiled coil complex elucidated from surface forces measurements

We used the Surface Forces Apparatus to elucidate the interaction mechanism between grafted 5 heptad-long peptides engineered to spontaneously form a heterodimeric coiled-coil complex. The results demonstrated that when intimate contact between peptides is reached, binding occurs first via weakly interacting but more mobile distal heptads, suggesting an induced-fit association process. Precise control of the distance between peptide-coated surfaces allowed to quantitatively monitor the evolution of their biding energy. The binding energy of the coiled-coil complex increased in a stepwise fashion rather than monotonically with the overlapping distance, each step corresponding to the interaction between a quantized number of heptads. Surface forces data were corroborated to surface plasmon resonance measurements and molecular dynamics simulations and allowed the calculation of the energetic contribution of each heptad within the coiled-coil complex.

Hold on or Cut? Integrin- and MMP-Mediated Cell-Matrix Interactions in the Tumor Microenvironment

The tumor microenvironment (TME) has become the focus of interest in cancer research and treatment. It includes the extracellular matrix (ECM) and ECM-modifying enzymes that are secreted by cancer and neighboring cells. The ECM serves both to anchor the tumor cells embedded in it and as a means of communication between the various cellular and non-cellular components of the TME. The cells of the TME modify their surrounding cancer-characteristic ECM. This in turn provides feedback to them via cellular receptors, thereby regulating, together with cytokines and exosomes, differentiation processes as well as tumor progression and spread. Matrix remodeling is accomplished by altering the repertoire of ECM components and by biophysical changes in stiffness and tension caused by ECM-crosslinking and ECM-degrading enzymes, in particular matrix metalloproteinases (MMPs). These can degrade ECM barriers or, by partial proteolysis, release soluble ECM fragments called matrikines, which influence cells inside and outside the TME. This review examines the changes in the ECM of the TME and the interaction between cells and the ECM, with a particular focus on MMPs.

Wavy nature of collagen fibrils deduced from the dispersion of their second-order nonlinear optical anisotropy parameters ρ

From P-SHG experiments, second-order nonlinear optical anisotropy parameters ρ = χ_ZZZ/χ_ZXX of collagen tissues are calculated assuming the same model of supercoiled collagen fibril characterized by a variable angle θ. Dispersion of experimental ρ values is converted into distribution of θ values based on the wavy nature of collagen fibrils deduced from EM studies. For tendon, the results show that the dispersion of experimental ρ values is mainly due to Poisson photonic shot noise assuming a slight fibrillar undulation with θ = 2.2^° ± 1.8^°. However for skin and vessels, the dispersion of experimental ρ values is mainly due to a stronger fibrillar undulation with θ = 16.2^° ± 1.3^°. The results highlight that this undulation is reduced during the development of liver fibrosis therefore, contributing to the rigidity of the tissue.

Photo-responsive azobenzene interactions promote hierarchical self-assembly of collagen triple-helical peptides to various higher-order structures

Collagen is an essential structural protein in animal tissues and plays key roles in cellular modulation. We investigated methods to discover collagen model peptides (CMPs) that would self-assemble into triple helices and then grow into supramolecular organizations with diverse morphological features, which would be valuable as biomaterials. This challenging undertaking was achieved by placing azobenzene groups on the ends of the CMPs, (GPO)_n (n = 3–10), Azo-(GPO)_n. In a dilute aqueous solution (80 μM), CD spectra indicated that the Azo-(GPO)_n (n > 4) formed triple helices due to strong hydrophobic azobenzene interactions, and that helix stability was increased with the peptide segment length. The resulting triple helices induced a specific azobenzene orientation through turned and twisted configurations as shown by CD spectra. TEM observations for the same solutions disclosed the morphologies for the Azo-CMPs. Azo-(GPO)₃, having the shortest peptide segment, showed no nanostructure, both Azo-(GPO)₄ and Azo-(GPO)₅ provided consistent well-developed nanofiber structures resembling the natural collagen fibers, and Azo-(GPO)_ns (n = 6–10) grew into flexible rod-like micelle fibers. In addition, alkyl chain-attached C_mAzo-(GPO)₅ displayed a toroidal morphology, and Azp-deg-(GPO)₅ having a hydrophilic spacer assembled into a bilayer vesicle structure. These diverse morphological features are considered to be due to the characteristics of the pre-organized triple helix units. Photo-isomerization of the azobenzene moiety brought about the disappearance of such characteristic nano-architectures. When the solution concentration was increased up to 1 wt%, only Azo-(GPO)₄ and Azo-(GPO)₅ spontaneously formed hydrogels exhibiting a satisfactory gel-to-sol transition upon UV irradiation.

Collagen is an essential structural protein in animal tissues and plays key roles in cellular modulation.

Serine-Arginine Protein Kinase SRPK2 Modulates the Assembly of the Active Zone Scaffolding Protein CAST1/ERC2

Neurons release neurotransmitters at a specialized region of the presynaptic membrane, the active zone (AZ), where a complex meshwork of proteins organizes the release apparatus. The formation of this proteinaceous cytomatrix at the AZ (CAZ) depends on precise homo- and hetero-oligomerizations of distinct CAZ proteins. The CAZ protein CAST1/ERC2 contains four coiled-coil (CC) domains that interact with other CAZ proteins, but also promote self-assembly, which is an essential step for its integration during AZ formation. The self-assembly and synaptic recruitment of the Drosophila protein Bruchpilot (BRP), a partial homolog of CAST1/ERC2, is modulated by the serine-arginine protein kinase (SRPK79D). Here, we demonstrate that overexpression of the vertebrate SRPK2 regulates the self-assembly of CAST1/ERC2 in HEK293T, SH-SY5Y and HT-22 cells and the CC1 and CC4 domains are involved in this process. Moreover, the isoform SRPK2 forms a complex with CAST1/ERC2 when co-expressed in HEK293T and SH-SY5Y cells. More importantly, SRPK2 is present in brain synaptic fractions and synapses, suggesting that this protein kinase might control the level of self-aggregation of CAST1/ERC2 in synapses, and thereby modulate presynaptic assembly.

Identification of early inflammatory changes in the tympanic membrane with Raman spectroscopy

The tympanic membrane (TM) is a dynamic structure that separates the middle ear from the external auditory canal. It is also integral for the transmission of sound waves. In this study, we demonstrate the feasibility of using Raman spectroscopy to identify early chemical changes resulting from inflammation in the TM that can serve as an indicator of acute otitis media. Bacterial lipopolysaccharide (LPS) was injected trans-tympanicaly in a murine model. Presence of inflammatory response was assessed with binocular microscopy, confirmed with histopathology and immunofluorescence staining. Successful discrimination suggesting spectral differences among the control and LPS treated groups was achieved using principal component analysis. Raman imaging revealed major differences in collagen distribution and nucleic acid content. Image segmentation analysis on the trichrome stained tissue sections was performed to corroborate the Raman spectra. The spectral co-localization study suggests changes in the expression of collagen IV specific signals in LPS treated samples. The overall findings of the study support prospective application of RS in the diagnosis and therapeutic monitoring of otitis media.

Development of a collagen-like peptide polymer via end-to-end disulfide cross-linking and its application as a biomaterial

Collagen is the most abundant protein in the animal kingdom and has a unique triple-helical structure. It not only provides mechanical strength to tissues, but also performs specific biological functions as a multifaceted signaling molecule. Animal-derived collagen is therefore widely used as a biocompatible material in vitro and in vivo. In this study, we developed a novel peptide-based material that mimicked both the polymeric properties and a selected biological function of native collagen. This material was prepared by end-to-end multiple disulfide cross-linking of chemically synthesized triple-helical peptides. The peptide polymer showed a gel-forming property, and receptor-specific cell binding was observed in vitro by incorporating a peptide harboring an integrin α2β1-binding sequence. Furthermore, cell signaling activity and biodegradability were tunable according to the polymer contents. The results demonstrated the potential of this material as a designer collagen. STATEMENT OF SIGNIFICANCE: Collagen is a useful biomaterial with the gel-forming property. It also exhibits various biological activities through the interaction of specific amino acid sequences displayed on the triple helix with functional biomacromolecules. Here we report a novel synthetic material, artificial collagen, by end-to-end cross-linking of chemically synthesized collagen-like triple-helical peptides. The material allows independent regulation of polymer properties, i.e. gel stiffness, and sequence-specific bioactivities by altering peptide compositions. This material can also be variously shaped, for example, thin films with high transparency. In addition, it has low inflamatogenic properties and tunable biodegradability in vivo.

Construction and Composition of the Squid Pen from Doryteuthis pealeii

The pen, or gladius, of the squid is an internalized shell. It serves as a site of attachment for important muscle groups and as a protective barrier for the visceral organs. The pen's durability and flexibility are derived from its unique composition of chitin and protein. We report the characterization of the structure, development, and composition of pens from Doryteuthis pealeii. The nanofibrils of the polysaccharide β-chitin are arranged in an aligned configuration in only specific regions of the pen. Chitin is secreted early in development, enabling us to characterize the changes in pen morphology prior to hatching. The chitin and proteins are assembled in the shell sac surrounded by fluid that has a significantly different ionic composition from squid plasma. Two groups of proteins are associated with the pen: those on its surface and those embedded within the pen. Only 20 proteins are identified as embedded within the pen. Embedded proteins are classified into six groups, including chitin associated, protease, protease inhibitors, intracellular, extracellular matrix, and those that are unknown. The pen proteins share many conserved domains with proteins from other chitinous structures. We conclude that the pen is one of the least complex, load-bearing, chitin-rich structures currently known and is amenable to further studies to elucidate natural construction mechanisms using chitin and protein.

Surface analysis of sheep menisci after meniscectomy via infrared attenuated total reflection spectroscopy

Menisci are very important fibrocartilaginous tissue, which maintain biomechanical functions and physiological stabilization of knee joint. Meniscectomy is known as a surgery to recover partial functions from acute meniscus tears. However, the late consequences of total or partial meniscectomy include signs of osteoarthritis and even ligament instability. Infrared attenuated total reflection (IR-ATR) spectroscopy is a very useful technique, which can reveal molecular characteristics via the analysis of vibrational bands. The present study has employed IR-ATR spectroscopy to investigate sheep menisci samples after meniscectomy in a label-free fashion. Several differences of peak absorbance change and peak shift were observed between the native healthy samples and the meniscectomy samples in distinct IR wavenumber regions, such as amide I band, amide II band, C-H bending band as well as the sugar band region. Combining the results from the collagen protein IR spectra, it can be speculated that six months after meniscectomy collagen fibrils on the incision lose its ordered arrangement and a decrease in the triple helical structure of collagen fibril is observed. In addition, the collagen fibrils and proteoglycan content might also be slight varied after meniscectomy.

The extracellular matrix in tumor progression and metastasis

The extracellular matrix (ECM) constitutes the scaffold of tissues and organs. It is a complex network of extracellular proteins, proteoglycans and glycoproteins, which form supramolecular aggregates, such as fibrils and sheet-like networks. In addition to its biochemical composition, including the covalent intermolecular cross-linkages, the ECM is also characterized by its biophysical parameters, such as topography, molecular density, stiffness/rigidity and tension. Taking these biochemical and biophysical parameters into consideration, the ECM is very versatile and undergoes constant remodeling. This review focusses on this remodeling of the ECM under the influence of a primary solid tumor mass. Within this tumor stroma, not only the cancer cells but also the resident fibroblasts, which differentiate into cancer-associated fibroblasts (CAFs), modify the ECM. Growth factors and chemokines, which are tethered to and released from the ECM, as well as metabolic changes of the cells within the tumor bulk, add to the tumor-supporting tumor microenvironment. Metastasizing cancer cells from a primary tumor mass infiltrate into the ECM, which variably may facilitate cancer cell migration or act as barrier, which has to be proteolytically breached by the infiltrating tumor cell. The biochemical and biophysical properties therefore determine the rates and routes of metastatic dissemination. Moreover, primed by soluble factors of the primary tumor, the ECM of distant organs may be remodeled in a way to facilitate the engraftment of metastasizing cancer cells. Such premetastatic niches are responsible for the organotropic preference of certain cancer entities to colonize at certain sites in distant organs and to establish a metastasis. Translational application of our knowledge about the cancer-primed ECM is sparse with respect to therapeutic approaches, whereas tumor-induced ECM alterations such as increased tissue stiffness and desmoplasia, as well as breaching the basement membrane are hallmark of malignancy and diagnostically and histologically harnessed.

Development of a Quantitative Assay for the Characterization of Human Collectin-11 (CL-11, CL-K1)

Collectin-11 (CL-11) is a pattern recognition molecule of the lectin pathway of complement with diverse functions spanning from host defense to embryonic development. CL-11 is found in the circulation in heterocomplexes with the homologous collectin-10 (CL-10). Abnormal CL-11 plasma levels are associated with the presence of disseminated intravascular coagulation, urinary schistosomiasis, and congenital disorders. Although there has been a marked development in the characterization of CL-11 there is still a scarcity of clinical tools for its analysis. Thus, we generated monoclonal antibodies and developed a quantitative ELISA to measure CL-11 in the circulation. The antibodies were screened against recombinant CL-11 and validated by ELISA and immunoprecipitation of serum and plasma. The best candidates were pairwise compared to develop a quantitative ELISA. The assay was validated regarding its sensitivity, reproducibility, and dilution linearity, demonstrating a satisfactory variability over a working range of 0.29–18.75 ng/ml. The mean plasma concentration of CL-11 in healthy controls was determined to be 289.4 ng/ml (range 143.2–459.4 ng/ml), highly correlated to the levels of CL/10/11 complexes (r = 0.729). Plasma CL-11 and CL-10/11 co-migrated in size exclusion chromatography as two major complexes of ~400 and >600 kDa. Furthermore, we observed a significant decrease at admission in CL-11 plasma levels in patients admitted to intensive care with systemic inflammatory response syndrome. By using the in-house antibodies and recombinant CL-11, we found that CL-11 can bind to zymosan independently of calcium by a separate site from the carbohydrate-binding region. Finally, we showed that CL-11/MASP-2 complexes trigger C4b deposition on zymosan. In conclusion, we have developed a specific and sensitive ELISA to investigate the ever-expanding roles of CL-11 in health and disease and shown a novel interaction between CL-11 and zymosan.

CROSS-LINKS MULTISCALE EFFECTS ON BONE ULTRASTRUCTURE BIOMECHANICAL BEHAVIOR

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.

Unraveling Mechanisms of Chiral Induction in Double-Helical Metallopolymers

Self-assembled helical polymers hold great promise as new functional materials, where helical handedness controls useful properties such as circularly polarized light emission or electron spin. The technique of subcomponent self-assembly can generate helical polymers from readily prepared monomers. Here we present three distinct strategies for chiral induction in double-helical metallopolymers prepared via subcomponent self-assembly: (1) employing an enantiopure monomer, (2) polymerization in a chiral solvent, (3) using an enantiopure initiating group. Kinetic and thermodynamic models were developed to describe the polymer growth mechanisms and quantify the strength of chiral induction, respectively. We found the degree of chiral induction to vary as a function of polymer length. Ordered, rod-like aggregates more than 70 nm long were also observed in the solid state. Our findings provide a basis to choose the most suitable method of chiral induction based on length, regiochemical, and stereochemical requirements, allowing stereochemical control to be established in easily accessible ways.

Structural Basis for the Acceleration of Procollagen Processing by Procollagen C-Proteinase Enhancer-1

Procollagen C-proteinase enhancer-1 (PCPE-1) is a secreted protein that specifically accelerates proteolytic release of the C-propeptides from fibrillar procollagens, a crucial step in fibril assembly. As such, it is a potential therapeutic target to improve tissue repair and prevent fibrosis, a major cause of mortality worldwide. Here we present the crystal structure of the active CUB1CUB2 fragment of PCPE-1 bound to the C-propeptide trimer of procollagen III (CPIII). This shows that the two CUB domains bind to two different chains of CPIII and that the N-terminal region of one CPIII chain, close to the proteolytic cleavage site, lies in the cleft between CUB1 and CUB2. This suggests that enhancing activity involves unraveling of this chain from the rest of the trimer, thus facilitating the action of the proteinase involved. Support for this hypothesis comes from site-directed mutagenesis, enzyme assays, binding studies, and molecular modeling.

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The crystal structure of PCPE-1 bound to the C-propeptides has been determined

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The N terminus of one propeptide chain binds to the CUB1CUB2 fragment of PCPE-1

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PCPE-1 seems to unravel the propeptide trimer to enable proteolytic release

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Molecular modeling with the proteinase and its substrate supports this hypothesis

Diffusion and Binding of Laponite Clay Nanoparticles into Collagen Fibers for the Formation of Leather Matrix

Understanding accessibility and interactions of clay nanoparticles with collagen fibers is an important fundamental issue for the conversion of collagen to leather matrix. In this study, we have investigated the diffusion and binding of Laponite into the collagen fiber network. Our results indicate that the diffusion behaviors of Laponite into the collagen exhibit the Langmuir adsorption, verifying its affinity for collagen. The introduction of Laponite leads to a shift in the isoelectric point of collagen from ∼6.8 to ∼4.5, indicating the ionic bonding between the positively charged amino groups of the collagen and negatively charged Laponite under the tanning conditions. Fluorescence microscopy, atomic force microscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and wide-angle X-ray diffraction analyses reveal that Laponite nanoparticles can penetrate into collagen microstructure and evenly distributed onto collagen fibrils, not altering native D-periodic banding patterns of collagen fibrils. Attenuated total reflectance-Fourier transform infrared and Raman spectroscopy detections further demonstrate the presence of noncovalent interactions, namely, ionic and hydrogen bonding, between Laponite and collagen. These findings provide a theoretical basis for the use of Laponite as an emerging tanning agent in leather manufacture.

More than a syllable in fib-ROS-is: The role of ROS on the fibrotic extracellular matrix and on cellular contacts

Fibrosis is characterized by excess deposition of extracellular matrix (ECM). However, the ECM changes during fibrosis not only quantitatively but also qualitatively. Thus, the composition is altered as the expression of various ECM proteins changes. Moreover, also posttranslational modifications, secretion, deposition and crosslinkage as well as the proteolytic degradation of ECM components run differently during fibrosis. As several of these processes involve redox reactions and some of them are even redox-regulated, reactive oxygen species (ROS) influence fibrotic diseases. Redox regulation of the ECM has not been studied intensively, although evidences exist that the alteration of the ECM, including the redox-relevant processes of its formation and degradation, may be of key importance not only as a cause but also as a consequence of fibrotic diseases. Myofibroblasts, which have differentiated from fibroblasts during fibrosis, produce most of the ECM components and in return obtain important environmental cues of the ECM, including their redox-dependent fibrotic alterations. Thus, myofibroblast differentiation and fibrotic changes of the ECM are interdependent processes and linked with each other via cell-matrix contacts, which are mediated by integrins and other cell adhesion molecules. These cell-matrix contacts are also regulated by redox processes and by ROS. However, most of the redox-catalyzing enzymes are localized within cells. Little is known about redox-regulating enzymes, especially the ones that control the formation and cleavage of redox-sensitive disulfide bridges within the extracellular space. They are also important players in the redox-regulative crosstalk between ECM and cells during fibrosis.

Genomics of Clostridium taeniosporum, an organism which forms endospores with ribbon-like appendages

Clostridium taeniosporum, a non-pathogenic anaerobe closely related to the C. botulinum Group II members, was isolated from Crimean lake silt about 60 years ago. Its endospores are surrounded by an encasement layer which forms a trunk at one spore pole to which about 12–14 large, ribbon-like appendages are attached. The genome consists of one 3,264,813 bp, circular chromosome (with 26.6% GC) and three plasmids. The chromosome contains 2,892 potential protein coding sequences: 2,124 have specific functions, 147 have general functions, 228 are conserved but without known function and 393 are hypothetical based on the fact that no statistically significant orthologs were found. The chromosome also contains 101 genes for stable RNAs, including 7 rRNA clusters. Over 84% of the protein coding sequences and 96% of the stable RNA coding regions are oriented in the same direction as replication. The three known appendage genes are located within a single cluster with five other genes, the protein products of which are closely related, in terms of sequence, to the known appendage proteins. The relatedness of the deduced protein products suggests that all or some of the closely related genes might code for minor appendage proteins or assembly factors. The appendage genes might be unique among the known clostridia; no statistically significant orthologs were found within other clostridial genomes for which sequence data are available. The C. taeniosporum chromosome contains two functional prophages, one Siphoviridae and one Myoviridae, and one defective prophage. Three plasmids of 5.9, 69.7 and 163.1 Kbp are present. These data are expected to contribute to future studies of developmental, structural and evolutionary biology and to potential industrial applications of this organism.

Analysis of human menisci degeneration via infrared attenuated total reflection spectroscopy

Degeneration of human meniscal tissue induces impairment of normal knee functions, and is a highly relevant etiology of knee joint tears and osteoarthritis.

Vectofusin-1, a potent peptidic enhancer of viral gene transfer forms pH-dependent α-helical nanofibrils, concentrating viral particles

Gene transfer using lentiviral vectors has therapeutic applications spanning from monogenic and infectious diseases to cancer. Such gene therapy has to be improved by enhancing the levels of viral infection of target cells and/or reducing the amount of lentivirus for greater safety and reduced costs. Vectofusin-1, a recently developed cationic amphipathic peptide with a pronounced capacity to enhance such viral transduction, strongly promotes the entry of several retroviral pseudotypes into target cells when added to the culture medium. To clarify the molecular basis of its action the peptide was investigated on a molecular and a supramolecular level by a variety of biophysical approaches. We show that in culture medium vectofusin-1 rapidly forms complexes in the 10 nm range that further assemble into annular and extended nanofibrils. These associate with viral particles allowing them to be easily pelleted for optimal virus-cell interaction. Thioflavin T fluorescence, circular dichroism and infrared spectroscopies indicate that these fibrils have a unique α-helical structure whereas most other viral transduction enhancers form β-amyloid fibrils. A vectofusin-1 derivative (LAH2-A4) is inefficient in biological assays and does not form nanofibrils, suggesting that supramolecular assembly is essential for transduction enhancement. Our observations define vectofusin-1 as a member of a new class of α-helical enhancers of lentiviral infection. Its fibril formation is reversible which bears considerable advantages in handling the peptide in conditions well-adapted to Good Manufacturing Practices and scalable gene therapy protocols.

Determination of extracellular matrix collagen fibril architectures and pathological remodeling by polarization dependent second harmonic microscopy

Polarization dependence second harmonic generation (P-SHG) microscopy is gaining increase popularity for in situ quantification of fibrillar protein architectures. In this report, we combine P-SHG microscopy, new linear least square (LLS) fitting and modeling to determine and convert the complex second-order non-linear optical anisotropy parameter ρ of several collagen rich tissues into a simple geometric organization of collagen fibrils. Modeling integrates a priori knowledge of polyhelical organization of collagen molecule polymers forming fibrils and bundles of fibrils as well as Poisson photonic shot noise of the detection system. The results, which accurately predict the known sub-microscopic hierarchical organization of collagen fibrils in several tissues, suggest that they can be subdivided into three classes according to their microscopic and macroscopic hierarchical organization of collagen fibrils. They also show, for the first time to our knowledge, intrahepatic spatial discrimination between genuine fibrotic and non-fibrotic vessels. CCl₄-treated livers are characterized by an increase in the percentage of fibrotic vessels and their remodeling involves peri-portal compaction and alignment of collagen fibrils that should contribute to portal hypertension. This integrated P-SHG image analysis method is a powerful tool that should open new avenue for the determination of pathophysiological and chemo-mechanical cues impacting collagen fibrils organization.

Proteomic differences in amyloid plaques in rapidly progressive and sporadic Alzheimer's disease

Rapidly progressive Alzheimer's disease (rpAD) is a particularly aggressive form of Alzheimer's disease, with a median survival time of 7-10 months after diagnosis. Why these patients have such a rapid progression of Alzheimer's disease is currently unknown. To further understand pathological differences between rpAD and typical sporadic Alzheimer's disease (sAD) we used localized proteomics to analyze the protein differences in amyloid plaques in rpAD and sAD. Label-free quantitative LC-MS/MS was performed on amyloid plaques microdissected from rpAD and sAD patients (n = 22 for each patient group) and protein expression differences were quantified. On average, 913 ± 30 (mean ± SEM) proteins were quantified in plaques from each patient and 279 of these proteins were consistently found in plaques from every patient. We found significant differences in protein composition between rpAD and sAD plaques. We found that rpAD plaques contained significantly higher levels of neuronal proteins (p = 0.0017) and significantly lower levels of astrocytic proteins (p = 1.08 × 10^-6). Unexpectedly, cumulative protein differences in rpAD plaques did not suggest accelerated typical sAD. Plaques from patients with rpAD were particularly abundant in synaptic proteins, especially those involved in synaptic vesicle release, highlighting the potential importance of synaptic dysfunction in the accelerated development of plaque pathology in rpAD. Combined, our data provide new direct evidence that amyloid plaques do not all have the same protein composition and that the proteomic differences in plaques could provide important insight into the factors that contribute to plaque development. The cumulative protein differences in rpAD plaques suggest rpAD may be a novel subtype of Alzheimer's disease.

Bioengineering towards self-assembly of particulate vaccines

There is an unmet demand for safe and efficient vaccines for prevention of various infectious diseases. Subunit vaccines comprise selected pathogen specific antigens are a safe alternative to whole organism vaccines. However they often lack immunogenicity. Natural and synthetic self-assembling polymers and proteins will be reviewed in view their use to encapsulate and/or display antigens to serve as immunogenic antigen carriers for induction of protective immunity. Recent advances made in in vivo assembly of antigen-displaying polyester inclusions will be a focus. Particulate vaccines are inherently immunogenic due to enhanced uptake by antigen presenting cells which process antigens mediating adaptive immune responses. Bioengineering approaches enable the design of tailor-made particulate vaccines to fine tune immune responses towards protective immunity.

Wavelength-Dependent Second Harmonic Generation Circular Dichroism for Differentiation of Col I and Col III Isoforms in Stromal Models of Ovarian Cancer Based on Intrinsic Chirality Differences

Extensive remodeling of the extracellular matrix (ECM) occurs in many epithelial cancers. For example, in ovarian cancer, upregulation of collagen isoform type III has been linked to invasive forms of the disease, and this change may be a potential biomarker. To examine this possibility, we implemented wavelength-dependent second harmonic generation circular dichroism (SHG-CD) imaging microscopy to quantitatively determine changes in chirality in ECM models comprised of different Col I/Col III composition. In these models, Col III was varied between 0 and 40%, and we found increasing Col III results in reduced net chirality, consistent with structural biology studies of Col I and III in tissues where the isoforms comingle in the same fibrils. We further examined the wavelength dependence of the SHG-CD to both optimize the response and gain insight into the underlying mechanism. We found using shorter SHG excitation wavelengths resulted in increased SHG-CD sensitivity, where this is consistent with the electric-dipole-coupled oscillator model suggested previously for the nonlinear chirality response from thin films. Moreover, the sensitivity is further consistent with the wavelength dependency of SHG intensity fit to a two-state model of the two-photon absorption in collagen. We also provide experimental calibration protocols to implement the SHG-CD modality on a laser scanning microscope. We last suggest that the technique has broad applicability in probing a wide range of diseased states with changes in collagen molecular structure.

Isolation, Characterization and Evaluation of Collagen from Jellyfish Rhopilema esculentum Kishinouye for Use in Hemostatic Applications

Hemostat has been a crucial focus since human body is unable to control massive blood loss, and collagen proves to be an effective hemostat in previous studies. In this study, collagen was isolated from the mesoglea of jellyfish Rhopilema esculentum Kishinouye and its hemostatic property was studied. The yields of acid-soluble collagen (ASC) and pepsin-soluble (PSC) were 0.12% and 0.28% respectively. The SDS-PAGE patterns indicated that the collagen extracted from jellyfish mesoglea was type I collagen. The lyophilized jellyfish collagen sponges were cross-linked with EDC and interconnected networks in the sponges were revealed by scanning electron microscope (SEM). Collagen sponges exhibited higher water absorption rates than medical gauze and EDC/NHS cross-linking method could improve the stability of the collagen sponges. Compared with medical gauze groups, the blood clotting indexes (BCIs) of collagen sponges were significantly decreased (P < 0.05) and the concentration of collagen also had an influence on the hemostatic property (P < 0.05). Collagen sponges had an improved hemostatic ability compared to the gauze control in tail amputation rat models. Hemostatic mechanism studies showed that hemocytes and platelets could adhere and aggregate on the surface of collagen sponge. All properties make jellyfish collagen sponge to be a suitable candidate used as hemostatic material and for wound healing applications.

Effect of Linear-Hyperbranched Amphiphilic Phosphate Esters on Collagen Fibers

The surfactants of the linear-hyperbranched phosphate esters (PAMAM_Gn-3-Ps) have been constructed through random multibranching esterification of lauroyl chloride and phosphate ester as a branching agent. Subsequently, a series of surfactant products were obtained. Benefiting from the amphiphilic structure with the hydrophilic core and many hydrophobic tails, PAMAM_Gn-3-Ps were able to self-assemble into nanomicelles in aqueous media. Importantly, the polymers show low critical micelle concentrations (CMCs) and small particle sizes. Here, PAMAM_G1-3-P was applied in the collagen fibers of leather to improve the fibers' distance and mechanical property of collagen fibers. Additionally, the polymers display significant flexibility, which could replace ordinary fatliquor in the future. The result provides a new application of using linear-hyperbranched amphiphilic phosphate esters into traditional leather materials to enhance the performance of collagen fibers.