Collagen Structure Research Articles

Preparation and tissue structure analysis of horse bone collagen peptide

Horse bone is rich in collagen, with a composition similar to that of human collagen. Collagen peptides supply nutrients needed for human growth that act as antioxidants, lower blood pressure. This study explored the extraction of collagen and the preparation of collagen short peptides from Mongolian horse bones. Bones were collected from horses of varying ages, and the collagen content along with calcium salt distribution were observed through staining and imaging analyses. Next, the bones were processed into a powder and then subjected to ultra-high-pressure processing for degreasing. The degreasing conditions were optimised by single-factor and orthogonal tests. Following this, collagen was extracted using an acid-enzymatic method, and its structural characteristics and thermal stability were assessed. The collagen short peptides were extracted from the collagen samples, and the effects of the enzymatic hydrolysis time, temperature, pH, and enzyme amount on the extraction rate were evaluated. Finally, the resulting collagen peptides were analysed for antioxidant activity. In summary, this experiment optimised the extraction conditions for horse bone collagen, demonstrating that the ultra-high-pressure method minimally affects collagen structure, and the extraction rate was high. Hence our method has significant development potential.

Changes in Texture and Collagen Properties of Pork Skin during Salt-Enzyme-Alkali Tenderization Treatment.

The effects of salt-enzyme-alkali progressive tenderization treatments on porcine cortical conformation and collagen properties were investigated, and their effectiveness and mechanisms were analyzed. The tenderization treatment comprised three treatment stages: CaCl2 (25 °C/0-30 min), papain (35 °C/30-78 min), and Na2CO3 (25 °C/78-120 min). The textural, microscopic, and collagenous properties (content, solubility, and structure) of pork skin were determined at the 0th, 30th, 60th, 90th, and 120th min of the treatment process. The results showed that the shear force, hardness, and chewability of the skin decreased significantly (p < 0.05), and the elasticity exhibited a gradual increase with the progression of tenderization. The content and solubility of collagen showed no significant change at the CaCl2 treatment stage. However, the soluble collagen content increased, the insoluble collagen content decreased, and the collagen solubility increased by 18.04% during the subsequent treatment with papain and Na2CO3. Meanwhile, the scanning electron microscopy results revealed that the regular, wavy structure of the pig skin collagen fibers gradually disappeared during the CaCl2 treatment stage, the overall structure revealed expansion, and the surface microscopic pores gradually increased during the papain and Na2CO3 treatment stages. The findings of the Fourier transform infrared spectroscopy analysis indicated that the hydrogen bonding interactions between the collagen molecules and the C=O, N-H and C-N bonds in the subunit structure of collagen were substantially altered during treatment and that the breakage of amino acid chains and reduction in structural ordering became more pronounced with prolonged treatment. In the tertiary structure, the maximum emission wavelength was blue-shifted and then red-shifted, and the fluorescence intensity was gradually weakened. The surface hydrophobicity was slowly increased. The salt-enzyme-alkali tenderization treatment considerably improved the physical properties and texture of edible pork skins by dissolving collagen fibers and destroying the structure of collagen and its interaction force.

Macrophages as Potential Therapeutic Targets in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a heterogenous malignant hemopathy, and although new drugs have emerged recently, current treatment options still show limited efficacy. Therapy resistance remains a major concern due to its contribution to treatment failure, disease relapse, and increased mortality among patients. The underlying mechanisms of resistance to therapy are not fully understood, and it is crucial to address this challenge to improve therapy. Macrophages are immune cells found within the bone marrow microenvironment (BMME), of critical importance for leukemia development and progression. One defining feature of macrophages is their plasticity, which allows them to adapt to the variations in the microenvironment. While this adaptability is advantageous during wound healing, it can also be exploited in cancer scenarios. Thus, clinical and preclinical investigations that target macrophages as a therapeutic strategy appear promising. Existing research indicates that targeting macrophages could enhance the effectiveness of current AML treatments. This review addresses the importance of macrophages as therapeutic targets including relevant drugs investigated in clinical trials such as pexidartinib, magrolimab or bexmarilimab, but also provides new insights into lesser-known therapies, like macrophage receptor with a collagenous structure (MACRO) inhibitors and Toll-like receptor (TLR) agonists.

Self-Assembly Behavior of Collagen and Its Composite Materials: Preparation, Characterizations, and Biomedical Engineering and Allied Applications.

Collagen is the oldest and most abundant extracellular matrix protein and has many applications in biomedical, food, cosmetic, and other industries. Previous reviews have already introduced collagen's sources, structures, and biosynthesis. The biological and mechanical properties of collagen-based composite materials, their modification and application forms, and their interactions with host tissues are pinpointed. It is worth noting that self-assembly behavior is the main characteristic of collagen molecules. However, there is currently relatively little review on collagen-based composite materials based on self-assembly. Herein, we briefly reviewed the biosynthesis, extraction, structure, and properties of collagen, systematically presented an overview of the various factors and corresponding characterization techniques that affect the collagen self-assembly process, and summarize and discuss the preparation methods and application progress of collagen-based composite materials in different fields. By combining the self-assembly behavior of collagen with preparation methods of collagen-based composite materials, collagen-based composite materials with various functional reactions can be selectively prepared, and these experiences and outcomes can provide inspiration and practical techniques for the future development directions and challenges of collagen-based composite biomaterials in related applications fields.

Sonication-Assisted Decellularization of Waste Tilapia (Oreochromis niloticus) Heads for Extracellular Matrix Extraction

Tilapia (Oreochromis niloticus), which is extensively farmed globally and ranks as the second most cultivated fish in the Philippines, generates significant amounts of waste that are often underutilized. One specific type of waste material consists of fish heads, which contain a valuable source of extracellular matrix (ECM). This study aims to evaluate the effects of sonication as a viable decellularization method for the extraction of ECM from tilapia fish heads. Particularly, two treatments were tested on the head samples: sonication-assisted decellularization (dWS) using a water bath sonicator, and decellularization without sonication (dNS), each with different contact times (5 min and 10 min). Histological analysis with H and E staining and DNA quantification revealed that sonication-assisted samples (dWS) showed a greater reduction in basophilic components and DNA content, achieving a 93.7% removal rate. These dWS samples also had the highest protein loss, retaining only 33.86% of the original protein. SDS–PAGE analysis indicated that both dWS and dNS samples maintained similar collagen structures, as evidenced by identical subunit bands. ATR–FTIR spectra confirmed the presence of collagen type I in all samples, detecting characteristic amides A, B, I, II, and III. The results revealed that varying treatments and contact times had significant effects on the physical and mechanical properties of the decellularized extracellular matrix (ECM). These findings highlight the effectiveness of sonication in the decellularization process, particularly for utilizing waste tilapia heads.

Integrating N -glycan and CODEX imaging reveal cell-specific protein glycosylation in healthy human lung.

N -linked glycosylation, the major post-translational modification of cellular proteins, is important for proper lung functioning, serving to fold, traffic, and stabilize protein structures and to mediate various cell-cell recognition events. Identifying cell-specific N -glycan structures in human lungs is critical for understanding the chemistry and mechanisms that guide cell-cell and cell-matrix interactions and determining nuanced functions of specific N -glycosylation. Our study, which used matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) combined with co-detection by indexing (CODEX) to reveal the cellular origin of N -glycans, is a significant step in this direction. This innovative technological combination enabled us to detect and differentiate N -glycans located in the vicinity of cells surrounding airways and blood vessels, parenchyma, submucosal glands, cartilage, and smooth muscles. The potential impact of our findings on future research is immense. For instance, our algorithm for grouping N -glycans based on their functional chemical features, combined with identifying group niches, paves the way for targeted studies. We found that fucosylated N -glycans are dominant around immune cells, tetra antennary N -glycans in the cartilage, high-mannose N -glycans surrounding the bronchus originate from associated collagenous structures, complex fucosylated-tetra antennary-polylactosamine N -glycans are spread over smooth muscle structures and in epithelial cells surrounding arteries, and N -glycans with Hex:6 HexNAc:6 compositions, which, according to our algorithm, can be ascribed to either tetra antennary or bisecting N -glycan, are highly abundant in the parenchyma. The findings suggest cell or region-specific functions for these localized glycan structures.

Collagen denaturation in post-run Achilles tendons and Achilles tendinopathy: In vivo mechanophysiology and magnetic resonance imaging.

Achilles tendinopathy is often attributed to overuse, but its pathophysiology remains poorly understood. Disruption to the molecular structure of collagen is fundamental for the onset and progression of tendinopathy but has mostly been investigated in vitro. Here, we interrogated the in vivo molecular structure changes of collagen in rat Achilles tendons following treadmill running. Unexpectedly, the tendons' collagen molecules were not mechanically unfolded by running but denatured through proteolysis during physiological post-run remodeling. We further revealed that running induces inflammatory gene expressions in Achilles tendons and that long-term running causes prolonged, elevated collagen degradation, leading to the accumulation of denatured collagen and tendinopathy development. For applications, we demonstrated magnetic resonance imaging of collagenase-induced Achilles tendon injury in vivo using a denatured collagen targeting contrast agent. Our findings may help close the knowledge gaps in the mechanobiology and pathogenesis of Achilles tendinopathy and initiate new strategies for its imaging-based diagnosis.

Structural determinants of tendon multiscale mechanics and their sensitivity to mechanical stimulation during development in an embryonic chick model

There is an abrupt increase in the multiscale mechanical properties and load-bearing capabilities of tendon during development. While prior work has identified numerous changes that occur within the collagenous structure during this developmental period, the primary structural elements that give rise to this abrupt increase in mechanical functionality, and their mechanobiological sensitivity, remain unclear. To address this knowledge gap, we used a shear lag model along with ultrastructural imaging, biochemical/thermodynamic assays, and multiscale mechanical testing to investigate the dynamic structure-function relationships during late-stage embryonic chick development and to establish their sensitivity to mechanical stimulation. Mechanical testing and modeling suggested that the rapid increase in multiscale mechanics can be explained by increases in fibril length, intrafibrillar crosslinking, and fibril area fraction. To partially test this, we inhibited collagen crosslinking during development and observed a drastic reduction in multiscale mechanical behavior that was explained by a reduction in both fibril modulus and length. Using muscle paralysis to investigate mechanosensitivity, we observed a significantly impaired multiscale mechanical response despite minimal changes in fibril diameter and fibril area fraction. Additionally, the shear lag model found a trend toward lower fibril lengths with paralysis and experimental data found decreased crosslinking and fibril modulus values following flaccid paralysis. Together, these data suggest that both intrafibrillar crosslink formation and fibril elongation are critical to the formation of load-bearing capabilities in tenogenesis and are sensitive to mechanical loading. These findings provide critical insights into the biological and structural mechanisms that give rise to tensile load-bearing soft tissue. Statement of SignificanceDespite prior work investigating the structural and mechanical changes that occur during tendon development, there has not been a comprehensive analysis of how these simultaneous changes in structure and function are connected. In this study, we performed a comprehensive battery of mechanical and structural assessments of embryonic chick tendons and input these data into a shear lag model to estimate the individual importance of each structural change to the tendon mechanical properties. Additionally, we inhibited muscle activity in the embryos to evaluate the impact of mechanical stimulation on these evolving structure-function relationships during tendon development. These data provide insight into the primary structural elements that produce the tensile load-bearing capabilities of tendon, which will inform efforts to produce tissue engineered tendon replacements.

Investigating the effect of water on collagen triple helix stability

Collagen provides essential structural support to diverse body tissues through its unique triple helix structure. Collagen stability is crucial for proper tissue function and any disruptions in its stability can lead to various health issues. Prior research has identified multiple factors affecting collagen stability. However, despite its fundamental presence in biological systems, the influence of water remains inadequately explored. Here, we performed molecular dynamics simulations on collagen model peptides (CMPs) with varying experimental stability profiles to investigate the influence of water on collagen stability. Our simulations revealed variations in both the hydrogen bonding (H-bonding) patterns between the CMPs and surrounding water molecules, as well as the water networks formed around CMPs. We noted that water molecules form H-bonds with collagen residues which enhance its structural stability. Additionally, water molecules assemble around the collagen and form topological water networks (TWNs) through intermolecular H-bonding. These TWNs further stabilizes the collagen structure. Overall, this research provides insight into the role of water molecules in preserving the stability of the collagen triple helix.

Eagle syndrome: tissue characteristics and structure of the styloid process.

Eagle syndrome is a bone disease where elongation of the styloid process leads to throat and neck pain, and in severe cases neurovascular symptoms such as syncope and neuralgia. The pathophysiology of Eagle syndrome is poorly understood with various theories having been proposed how this elongation is caused. To better understand the pathophysiology, we performed a work-up in 6 patients presenting with Eagle syndrome. Patients mainly presented with pain on turning the neck (100%), foreign body sensation (67%), tension in the neck (67%), and dysphagia (50%). The typical length of the styloid process ranges from 25 to 30 mm; however, [18F]NaF (sodium fluoride) PET/CT showed elongated styloid processes with an average length of 52.1 ± 15.6mm (mean ± SD) with increased turnover at the base of one of the styloid processes. The removed styloid processes were further examined by histology, micro-CT, quantitative backscatter electron imaging (qBEI), Fourier transform infrared spectroscopy (FTIR), and circularly polarized light imaging. Histology revealed one case of a fractured styloid process healing through callus formation and one case of pseudarthrosis. Bone mineral density and mineralization was similar in the styloid processes when compared to cortical bone samples derived from the mandibular bone of different patients. Circular polarized light microscopy showed a collagen orientation in the styloid process comparable to the cortical bone samples with a distinct separation of collagen structure between the mineralized structure and the surrounding soft tissue with FTIR analysis demonstrating a typical composition of bone. This altogether suggests that the elongated styloid processes in Eagle syndrome are mature bone, capable of endochondral repair, possibly growing from the base of the process through endochondral ossification, rather than being a form of secondary calcification of the stylohyoid ligament as previously postulated.

Advancing Boiling Histotripsy Dose in Ex Vivo And In Vivo Renal Tissues Via Quantitative Histological Analysis and Shear Wave Elastography

ObjectiveIn the context of developing boiling histotripsy (BH) as a potential clinical approach for non-invasive mechanical ablation of kidney tumors, the concept of BH dose (BHD) was quantitatively investigated in porcine and canine kidney models in vivo and ex vivo. MethodsVolumetric lesions were produced in renal tissue using a 1.5-MHz 256-element HIFU-array with various pulsing protocols: pulse duration tp = 1–10 ms, number of pulses per point ppp = 1–15. Two BHD metrics were evaluated: BHD1 = ppp, BHD2 = tp × ppp. Quantitative assessment of lesion completeness was performed by their histological analysis and assignment of damage score to different renal compartments (i.e., cortex, medulla, and sinus). Shear wave elastography (SWE) was used to measure the Young's modulus of renal compartments in vivo vs ex vivo, and before vs after BH treatments. ResultsIn vivo tissue required lower BH doses to achieve identical degree of fractionation as compared to ex vivo. Renal cortex (homogeneous, low in collagen) was equal or higher in stiffness than medulla (anisotropic, collagenous), 5.8–12.2 kPa vs 4.7–9.6 kPa, but required lower BH doses to be fully fractionated. Renal sinus (fatty, irregular, with abundant collagenous structures) was significantly softer ex vivo vs in vivo, 4.9–5.1 kPa vs 9.7–15.2 kPa, but was barely damaged in either case with any tested BH protocols. BHD1 was shown to be relevant for planning the treatment of renal cortex (sufficient BHD1 = 5 pulses in vivo and 10 pulses ex vivo), while none of the tested doses resulted in complete fractionation of medulla or sinus. Post-treatment SWE imaging revealed reduction of tissue stiffness ex vivo by 27–58%, increasing with the applied dose, and complete absence of shear waves within in vivo lesions, both indicative of tissue liquefaction. ConclusionThe results imply that tissue resistance to mechanical fractionation, and hence required BH dose, are not solely determined by tissue stiffness but also depend on its composition and structural arrangement, as well as presence of perfusion. The SWE-derived reduction of tissue stiffness with increasing BH doses correlated with tissue damage score, indicating potential of SWE for post-treatment confirmation of BH lesion completeness.

Static magnetic field effects on the secondary structure and elasticity of collagen molecules; a possible biophysical approach to treat keratoconus

Type I collagen is among the major extracellular proteins that play a significant role in the maintenance of the cornea's structural integrity and is essential in cell adhesion, differentiation, growth, and integrity. Here, we investigated the effect of 300 mT Static Magnetic Field (300 mT SMF) on the structure and molecular properties of acid-solubilized collagens (ASC) isolated from the rat tail tendon. The SMF effects at molecular and atomic levels were investigated by various biophysical approaches like Circular Dichroism Spectropolarimetery (CD), Fourier Transform Infrared Spectroscopy (FTIR), Zetasizer light Scattering, and Rheological assay. Exposure of isolated type I collagen to 300 mT SMF retained its triple helix. The elasticity of collagen molecules and the keratoconus (KCN) cornea treated with SMF decreased significantly after 5 min and slightly after 10, 15, and 20 min of treatments. The exposure to 300 mT SMF shifted the Amid I bond random coil to antiparallel wave number from 1647 to 1631 cm−1. The pH of the 300 mT SMF treated collagen solution increased by about 25 %. The treatment of the KCN corneas with 300 mT SMF decreased their elasticity significantly. The promising results of the effects of 300 mT SMF on the collagen molecules and KCN cornea propose a novel biophysical approach capable of manipulating the collagen's elasticity, surface charges, electrostatic interactions, cross binding, network formation and fine structure. Therefore, SMF treatment may be considered as a novel non-invasive, direct, non-chemical and fast therapeutic and manipulative means to treat KCN cornea where the deviated physico-chemical status of collagen molecules cause deformation.

Effects of Plant Meristem-Cell-Based Cosmetics on Menopausal Skin: Clinical Data and Mechanisms.

A randomised open clinical/laboratory study was performed to evaluate the safety and cosmetic efficacy of facial cosmetics for females during the menopausal period. The cosmetics contain active ingredients of meristem cells derived from the medicinal plants Leontopodium alpinum, Buddeleja davidii, Centella asiatica, and Echinacea angustifolia. Recently, the major bioactive molecules of these medicinal plants (leontopodic acid, verbascoside, asiaticoside, and echinacoside, respectively) have been thoroughly evaluated in vitro for molecular pathways and cellular mechanisms and their preventive/curative effects on human skin cells exposed to factors promoting premature skin ageing and cellular senescence. Nevertheless, clinical data on their safety/efficacy to ageing human skin are scarce. This clinical study enrolled 104 Caucasian females in pre-menopause, menopause, or post-menopause periods. They applied cosmetic serums daily for 1 month. Questionnaires and instrumental and biochemical methods were used to assess dermatological/ophthalmological safety and cosmetic efficacy through changes of the skin physiology markers characteristic of ageing/menopause (elasticity, barrier functions, moisture, sebum, ultrasonic properties, and collagen content and structure). Quantitative microbiological tests were carried out for skin microbiota fluctuations. Data showed that the cosmetics were safe, and they shifted the skin physiology parameters to a younger biological age, enhanced collagen synthesis, inhibited lipid peroxidation, and favoured normal microbiota.

Carbon Fiber-Mediated Electrospinning Scaffolds Can Conduct Electricity for Repairing Defective Tendon.

Partial or complete rupture of the tendon can damage the collagen structure, resulting in the disruption of the electrical signal pathway. It is a great challenge to reconstruct the original electrical signal pathway of the tendon and promote the regeneration and functional recovery of defective tendon. In this study, carbon fiber-mediated electrospinning scaffolds were fabricated by wrapping conductive, high-strength, loose single-bundle carbon fibers with nanofiber membranes. Due to the presence of nanofiber membranes, the maximum tensile force of the scaffolds was 2.4 times higher than that of carbon fibers, while providing excellent temporal and spatial prerequisites for tenocytes to adapt to electrical stimulation to accelerate proliferation and expression. The diameter of the carbon fiber monofilaments used in this study was 5.07 ± 1.20 μm, which matched the diameter of tendon collagen, allowing for quickly establishing the connection between the tendon tissue and the scaffold, and better promoting the recovery of the electrical signal pathway. In a rabbit Achilles tendon defect repair model, the carbon fiber-mediated electrospinning scaffold was almost filled with collagen fibers compared to a nonconductive polyethylene glycol terephthalate scaffold. Transcriptome sequencing revealed that fibromodulin and tenomodulin expression were upregulated, and their related proteoglycans and glycosaminoglycan binding proteins pathways were enhanced, which could regulate the TGF-β signaling pathway and optimize the extracellular matrix assembly, thus promoting tendon repair. Therefore, the scaffold in this study makes up for the shortage of conductive scaffolds for repairing tendon defects, revealing the potential impact of conductivity on the signaling pathway of tendon repair and providing a new approach for future clinical studies.

Interpenetrating networks of fibrillar and amorphous collagen promote cell spreading and hydrogel stability.

Collagen hydrogels are widely used as scaffolds for tissue engineering due to their support of cellular activity. However, collagen hydrogels often undergo undesired changes in size and shape due to cell-generated forces, and conventional strategies to mitigate this deformation typically compromise either the fibrillar microstructure or cytocompatibility of the collagen. In this study, we introduce an innovative interpenetrating network (IPN) that combines physically self-assembled, fibrillar collagen-ideal for promoting cell adhesion and spreading-with covalently crosslinked, amorphous collagen-ideal for enhancing bulk hydrogel stability. Our IPN design maintains the native fibrillar structure of collagen while significantly improving resistance against cell-induced contraction, providing a promising solution to enhance the performance and reliability of collagen hydrogels for tissue engineering applications.

Cinobufagin inhibits M2‑like tumor‑associated macrophage polarization to attenuate the invasion and migration of lung cancer cells.

Macrophages have crucial roles in immune responses and tumor progression, exhibiting diverse phenotypes based on environmental cues. In the present study, the impact of cinobufagin (CB) on macrophage polarization and the consequences on tumor‑associated behaviors were investigated. Morphological transformations of THP‑1 cells into M0, M1 and M2 macrophages were observed, including distinct changes in the size, shape and adherence properties of these cells. CB treatment inhibited the viability of A549 and LLC cells in a concentration‑dependent manner, with an IC50 of 28.8 and 30.12 ng/ml, respectively. CB at concentrations of <30 ng/ml had no impact on the viability of M0 macrophages and lung epithelial (BEAS‑2B) cells. CB influenced the expression of macrophage surface markers, reducing CD206 positivity in M2 macrophages without affecting CD86 expression in M1 macrophages. CB also altered certain expression profiles at the mRNA level, notably downregulating macrophage receptor with collagenous structure (MARCO) expression in M2 macrophages and upregulating tumor necrosis factor‑α and interleukin‑1β in both M0 and M1 macrophages. Furthermore, ELISA analyses revealed that CB increased the levels of pro‑inflammatory cytokines in M1 macrophages and reduced the levels of anti‑inflammatory factors in M2 macrophages. CB treatment also attenuated the migration and invasion capacities of A549 and LLC cells stimulated by M2 macrophage‑conditioned medium. Additionally, CB modulated peroxisome proliferator‑activated receptor γ (PPARγ) and MARCO expression in M2 macrophages and epithelial‑mesenchymal transition in A549 cells, which was partially reversed by rosiglitazone, a PPARγ agonist. Finally, CB and cisplatin treatments hindered tumor growth in vivo, with distinct impacts on animal body weight and macrophage marker expression in tumor tissues. In conclusion, the results of the present study demonstrated that CB exerted complex regulatory effects on macrophage polarization and tumor progression, suggesting its potential as a modulator of the tumor microenvironment and a therapeutic for cancer treatment.

Healing Potential of the Marine Polysaccharides Carrageenan and Ulvan on Second-Degree Burns.

The treatment of second-degree burn wounds presents a significant clinical challenge, often characterized by prolonged healing times and risk of complications. In this study, the wound healing potential of bioactive marine sulfated polysaccharides ulvan and carrageenan formulated in gels at concentrations of 1.5%, 5.0%, and 10% w/w was evaluated. Hairless female SKH-hr2 mice (n = 7 per treatment) with burn-inflamed skin were treated with the polysaccharide-based gels, and the therapeutic efficacy was assessed using a comprehensive array of evaluation methods, including a histopathological analysis, clinical observation, photo-documentation, an image analysis, an evaluation of biophysical skin parameters, and FT-IR spectroscopy. Our findings indicate that the 10% w/w carrageenan gel exhibited significant enhancement in wound healing, particularly in the early stages of the healing process. This was evidenced by the restoration of the α-helix structure of collagen and the configuration of glycosaminoglycans, as demonstrated by FT-IR absorption bands of the skin both in vivo and ex vivo. Furthermore, the 5% w/w ulvan gel also demonstrated notable efficacy in promoting wound healing, particularly in the later stages of the healing process. These results suggest that carrageenan and ulvan gels hold promise for improving the efficiency of wound healing in second-degree burn wounds. Our study contributes to the understanding of the therapeutic potential of marine polysaccharides and provides insights into their mechanism of action in promoting wound healing.

Peptidic "Molecular Beacon" for Collagen.

Collagen-mimetic peptides (CMP) have been invaluable tools for understanding the structure and function of collagen, which is the most abundant protein in animals. CMPs have also been developed as probes that detect damaged collagen because of the specificity required to form a collagen triple helix. These probes are not, however, ratiometric. Here, we used EPR spectroscopy to determine the end-to-end distances of CMPs that do not form stable homotrimeric helices. We found that those distances are shorter than the distances in the context of a collagen triple helix, suggesting their potential utility as a "molecular beacon" and guiding the choice and location of a pendant fluorophore-quencher pair. We then showed that a molecular beacon based on a glycine-(2S,4S)-4-fluoroproline-(2S,4R)-4-hydroxyproline tripeptide repeat and EDANS-DABCYL pair enabled the ratiometric detection of its binding to both other CMPs and natural mammalian collagen. These results provide guidance for the development of a new modality for detecting damaged collagen in physiological settings.

Insights into the Structural and Thermal Properties of Pepsin-Soluble Collagen from Daggertooth pike conger (Muraenesox cinereus)

Pepsin soluble collagen (PSC) is a type-1 collagen which is abundant in skin. The pepsin soluble collagen was successfully extracted from the skin of Daggertooth pike conger (Muraenesox cinereus) by using the conventional method of salt precipitation followed by dialysis. Pepsin-soluble collagen showed a yield of 10.12% on wet matter basis and 25.5% on dry matter basis. The triple helical structure of collagen was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible spectrophotometry. Isolated PSC was confirmed as type 1 collagen by Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). FTIR spectra of PSC suggested that the secondary structure of the triple helical collagen was intact even after pepsin digestion. Pepsin-soluble collagen was soluble in acidic pH with maximum solubility at pH 4. The solubility was found to be decreased with an increase in the concentration of sodium chloride with a minimum solubility at 4%. The present PSC isolate from eel fish exhibited comparatively high thermal stability of 36 ͦ C. Morphological analysis by Scanning electron microscopy (SEM) revealed a porous structure and comparatively high thermal stability makes it a promising biomaterial.

A literature review of allergen properties in fish collagen and its derivative products

Fish are generally categorized as allergens that cause reactions mediated by Immunoglobulin E (IgE). Fish collagen is one of the causes of allergic reactions, ranging from mild symptoms such as nausea and itching to severe symptoms such as anaphylaxis across all ages. Previous research has not specifically or comprehensively explained the characteristics of fish collagen and its derivatives as allergens. This study aims to address this gap by explaining the properties, contributing factors, and potential hazards of fish collagen and its derivatives as allergens. This research employed a literature review summarizing several main studies to produce comprehensive findings. The structure of collagen, contaminant allergens, and fish type can affect the allergenicity of fish collagen. Processing methods, such as heating, acid or enzyme treatment, and washing, can determine allergenicity. The structure of fish collagen can change upon heating, but its allergenicity cannot be reduced. Fish collagen is also known to have good resistance to enzymes; therefore, it can easily bind to immune cells. Another factor was age, in which adults had a greater frequency of IgE binding to fish collagen than did children and adolescents. They were included as potential allergens based on research results and existing data regarding allergy cases and their potential hazards. Therefore, there is a need for further research on allergies to fish collagen and its derivatives, especially in countries that do not require the inclusion of allergens where food safety matters.