Fibril matrices created with collagen from the marine fish barramundi for use in conventional three-dimensional cell culture

Extraction, characterization, and hemostatic effect of collagen from the scales of Megalonibea fusca

Marine collagen is gaining more attraction than terrestrial collagen because it is free of zoonotic disease and religious constrain. In this study, we aimed to investigate and compare the physicochemical properties and functional characteristics of acid-soluble collagen (ASC-MF) and pepsin-soluble collagen (PSC-MF) extracted from scales of Megalonibea fusca. ASC-MF and PSC-MF were evaluated in terms of yield, collagen type, amino acid composition, thermal stability, microstructure, cytotoxicity, and other physicochemical parameters. ASC-MF and PSC-MF depicted 1.72 ± 0.2% and 11.72 ± 0.3% of dry weight yields, respectively, and were identified as type I collagen with an intact triple-helical structure by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), spectroscopic analysis, and electron microscopy. Additionally, compared with many temperate and tropical species, ASC-MF and PSC-MF showed higher thermal stability, with the maximum transition temperature (Tmax) of 53.50°C (ASC-MF) and 43.16°C (PSC-MF). CCK-8 assay showed that ASC-MF and PSC-MF have no cytotoxicity in vitro. The determination of blood clotting index values showed that both ASC-MF and PSC-MF had good hemostatic ability. In summary, these findings show that PSC-MF isolated from the scales of M. fusca may be a feasible alternative to terrestrial collagen sources in food and biomedical applications.

Hierarchical Design of Tissue-Mimetic Fibrillar Hydrogel Scaffolds

Most tissues of the human body present hierarchical fibrillar extracellular matrices (ECMs) that have a strong influence over their physicochemical properties and biological behavior. Of great interest is the introduction of this fibrillar structure to hydrogels, particularly due to the water-rich composition, cytocompatibility, and tunable properties of this class of biomaterials. Here, the main bottom-up fabrication strategies for the design and production of hierarchical biomimetic fibrillar hydrogels and their most representative applications in the fields of tissue engineering and regenerative medicine are reviewed. For example, the controlled assembly/arrangement of peptides, polymeric micelles, cellulose nanoparticles (NPs), and magnetically responsive nanostructures, among others, into fibrillar hydrogels is discussed, as well as their potential use as fibrillar-like hydrogels (e.g., those from cellulose NPs) with key biofunctionalities such as electrical conductivity or remote stimulation. Finally, the major remaining barriers to the clinical translation of fibrillar hydrogels and potential future directions of research in this field are discussed.

Stability protection of lutein emulsions by utilizing a functional conjugate of collagen and Lycium barbarum L. leaf flavonoid

Lutein exhibits excellent functional activity making it useful in many fields. Nevertheless, its use is limited by its physical and chemical instability. Here, collagen and Lycium barbarum L. leaf flavonoids (LBLF) were used as emulsifiers, their structures were characterized, the properties of the complexes were evaluated, and their stabilizing effects on lutein emulsions were explored. According to the results, the encapsulation rate of the complex of collagen-LBLF was (68.67 ± 1.43) % and the drug loading was (6.92 ± 0.13) %. Collagen compounded LBLF with a changed structure and morphology, resulting in improved antioxidant capacity, better foaming and emulsification, and reduced hydrophobicity. In addition, the thiobarbituric acid value of collagen-LBLF stabilized lutein emulsion (0.0012 ± 0.00011) mg/kg was significantly lower than that of collagen stabilized lutein emulsion (0.0021 ± 0.00016)  mg/kg (P < 0.05), indicating that the composite stabilized lutein emulsion obtained higher stability. LBLF contributed a high free radical scavenging effect and inhibited lutein degradation during storage. During simulated digestion, collagen-LBLF effectively stabilized the emulsion and protected lutein from destruction, made it release more slowly, and benefited the bio-accessibility of lutein during the next utilization step. Based on the present study, improved storage and digestion stabilities of lutein wereachievedby the utilization of collagen-LBLF complex, which provides a new method for the preparation and application of composite functional emulsifiers.

Carboxy-terminal telopeptide levels of type I collagen hydrogels modulated the encapsulated cell fate for regenerative medicine

The cellular microenvironment has a profound impact on cell proliferation, interaction, and differentiation. In cell encapsulation for disease therapy, type I collagen is an important biomaterial due to its ability to mimic the extracellular matrix. Telopeptides (carboxy-terminal, CTX, and amino-terminal, NTX) protruding from the triple helix structure of type I collagen are cross-link sites, but also mediate the signal transmission in tissue homeostasis. It is worth investigating the features of the hydrogel microenvironment shaped by the tissue-derived type I collagen with various telopeptide levels, which is paramount for encapsulated cell development. Here, we found the fate of encapsulated human adipose-derived stem cells (hADSCs) and human umbilical vein endothelial cells (HUVECs) behaved differently towards decreasing CTX levels in the collagen hydrogels. Even among collagen hydrogels with a small magnitude of CTX variation, similar stiffness and microstructure, the apparent CTX modulation on the proliferation, cell-interaction, and genes expression of encapsulated hADSCs, as well as morphology and tubule structure formation of endothelial cells were observed, suggesting the biological roles of CTX and its modulation on microenvironment for cell development.

Collagen-based hydrogels cross-linked via laccase - mediated system incorporated with Fe3+ for wound dressing

Pure fish skin collagen hydrogels as a wound dressing have lower thermodynamic stability than mammalian collagen and usually suffer from poor mechanical properties, weak degradation resistance and insufficient functionalities such as antioxidant and anti-inflammatory properties to meet clinical needs that limit its further application. Here, a silver carp skin collagen hydrogel is successfully constructed via the cross-linking of the laccase-protocatechuic aldehyde (LAC-PAL) and the structure of the hydrogel is further consolidated and strengthened by the interaction of PAL and Fe3+. In this collagen hydrogel system, Fe3+, acting as a second cross-linker, consolidates and enhances the stability of the hydrogel after LAC-PAL cross-linking. This cross-linking method improves the resistance to degradation with a reduction in its degradation rate from 89.45% to 38.66% and endows the hydrogel with antioxidant activity. The in vitro data show that the hydrogel promotes cell proliferation and adhesion exhibiting good biocompatibility. Animal experiments show that the hydrogel contributes to angiogenesis and improves inflammatory response in the early stages of wound healing, resulting in promoting wound healing. Altogether, this newly developed collagen hydrogel is expected to be applied in wound repair as a wound dressing.

Preparation and Characterization of Tilapia Collagen-Thermoplastic Polyurethane Composite Nanofiber Membranes

Marine collagen is an ideal material for tissue engineering due to its excellent biological properties. However, the limited mechanical properties and poor stability of marine collagen limit its application in tissue engineering. Here, collagen was extracted from the skin of tilapia (Oreochromis nilotica). Collagen-thermoplastic polyurethane (Col-TPU) fibrous membranes were prepared using tilapia collagen as a foundational material, and their physicochemical and biocompatibility were investigated. Fourier transform infrared spectroscopy results showed that thermoplastic polyurethane was successfully combined with collagen, and the triple helix structure of collagen was retained. X-ray diffraction and differential scanning calorimetry results showed relatively good compatibility between collagen and TPU.SEM results showed that the average diameter of the composite nanofiber membrane decreased with increasing thermoplastic polyurethane proportion. The mechanical evaluation and thermogravimetric analysis showed that the thermal stability and tensile properties of Col-TPU fibrous membranes were significantly improved with increasing TPU. Cytotoxicity experiments confirmed that fibrous membranes with different ratios of thermoplastic polyurethane content showed no significant toxicity to fibroblasts; Col-TPU fibrous membranes were conducive to the migration and adhesion of cells. Thus, these Col-TPU composite nanofiber membranes might be used as a potential biomaterial in tissue regeneration.