Wounds caused by trauma, burns, diabetes, and surgery have threatened human health, and wound management has become a serious clinical challenge and economic burden. Collagen-based hydrogels have good biological activity, biocompatibility, and biodegradability, which make them have broad application prospects as wound dressings in different stages of wound healing and different types of wound healing. In this paper, the advantages and composition characteristics of collagen-based hydrogel dressings and their function mechanism in different wound healing processes such as hemostasis, inflammatory, proliferation, and remodeling are systematically reviewed. To summarize, the main molecular mechanisms of collagen-based hydrogel dressings include the provision of abundant nutrients at various stages, modulation of related cytokines (e.g., CD34, bFGF, and CTGF), inducement of signaling pathways (such as TGF-β/Smad, PI3K/Akt/mTOR), and promotion of the synthesis of ECM components, especially collagen. Thus, throughout the wound healing process, collagen-based hydrogel dressings can accelerate wound hemostasis, reduce inflammation, promote cell proliferation (especially of fibroblasts), aid in angiogenesis, enhance collagen synthesis, accelerate granulation tissue formation and re-epithelialization, and remodel the cytoplasmic matrix, ultimately leading to wound closure. Furthermore, this review discusses the existing problems in clinical application and scale production and outlines the future of development directions in the researches of collagen-based hydrogel dressings combining innovative wound treatment technologies, preparation technologies, and structural design methods, in order to inspire more new advancement and progress.

Mycelium has emerged as a promising bio-based material for the development of sustainable leather alternatives, driven by the increasing demand for eco-friendly materials. This work explores the crosslinking mechanism of mycelial leather alternatives treated with genipin tanning, focusing on the interactions between genipin and mycelium fibers. Genipin tanning agent interacts with nitrogen-containing groups and carboxyl groups in mycelial polysaccharides, inducing conformational changes in glycosides and increasing the thermal and structural stability of the mycelial leather alternative. Moreover, the synergistic effect of genipin tanning and glycerol fatliquoring resulted in a more organized and compact structure, with mycelial fibers tightly interwoven. The mycelial leather alternative demonstrated a tensile strength of 6.1 MPa, an elongation at break of 73.1%, as well as excellent thermal stability. The observed improved physical properties were attributed to the crosslinking of genipin with mycelial fibers and hydrogen bond formation between glycerol molecules and the hydroxyl groups on the fibers. Furthermore, the mycelial leather alternative demonstrated strong environmental performance, with more than 50% biodegradation in soil within 50 days. Its incineration produces fewer waste gases compared with traditional sheep leather. This work demonstrates the feasibility of using tanning methods to treat mycelial materials, providing valuable insights for advancing the development of leather alternatives.

Thyroid diseases, encompassing both thyroid dysfunction and benign or malignant thyroid nodules, are among the most prevalent disorders within the endocrine system. However, in some cases, current diagnostic approaches for different thyroid diseases lack precision, and therapeutic strategies for advanced tumors remain suboptimal in terms of efficacy. The recent emergence of nanomaterials and collagen have introduced novel paradigms for advancing the clinical diagnosis and management of thyroid disorders. Nanomaterials engineered with tailored designs enable exceptional precision in lesion targeting and ultra-sensitive detection of serum biomarkers. Furthermore, their superior biocompatibility and robust stability have been harnessed to optimize targeted drug delivery and controlled release systems, thereby enhancing therapeutic value while minimizing off-target damage to healthy tissues. As a primary constituent of the natural extracellular matrix, collagen serves as an innate biopolymer nanomaterial. Its nanostructured forms (including fibers, particles, and hydrogels) demonstrate extensive biomedical applicability, facilitating thyroid cell adhesion and functional regeneration while offering an optimal substrate for implantable diagnostic and therapeutic devices. This review highlights nanomaterials’ diagnostic/therapeutic advancements for thyroid diseases, discusses clinical challenges, and outlines future directions. Collagen, beyond being a nanomaterial adjunct, shows standalone promise in regenerative medicine, potentially enabling novel precision approaches.

Tannic acid (TA) is a widely available plant-derived polyphenol with a long history of use in the leather industry due to its strong affinity for collagen. This long-standing application stems from the ability of TA to form stable complexes with collagen and gelatin via multiple interactions, making it not only a natural tanning agent but also a valuable crosslinker in modern biomaterials. In recent years, TA has garnered increasing attention in wound healing applications because of its multifunctional bioactivities, including antibacterial, antioxidant, anti-inflammatory, and hemostatic effects. The abundant phenolic hydroxyl groups enable various covalent and noncovalent interactions (such as hydrogen bonding, metal coordination, π–π stacking, and oxidative coupling) with biomacromolecules and inorganic components, thereby enhancing the mechanical properties and biological functions of the hydrogel. This review summarizes the historical background and physicochemical properties of TA, introduces current hydrogel construction strategies (e.g., polymer blending and postfabrication immersion), and highlights the roles of TA in modulating the wound microenvironment by combating infection, scavenging reactive oxygen species, regulating inflammation, and promoting tissue regeneration. Advances in the use of TA-based hydrogels for treating acute, infected, and chronic wounds and other types of tissue injury are discussed. Furthermore, this review addresses the significant challenges—namely, stability, mechanistic understanding, and biosafety—in the clinical translation of TA-based hydrogels and discusses potential strategies for future development.

This work was conducted to prepare the transglutaminase (TGase) cross-linked collagen gel (CGL) by using pork skin as raw material, and to systematically investigate its digestive and absorptive properties and serum metabolism regulation in mice. The analysis of peptidomics revealed that CGL exhibited a lower average molecular weight of peptides (803.78 Da) and a higher proportion of small molecular peptides (11.22% of <500 Da) in the gastric digestion stage, indicating that the crosslinked structure significantly enhanced the hydrolysis efficiency of pepsin. After entering the small intestine, the proportion of small peptides (<500 Da) in the CGL group decreased compared to the gastric stage, and the number of small peptides in the CGL group decreased compared to the collagen sol (CSL) group, indicating that small peptides in the CGL group were rapidly absorbed in the small intestine stage. Meanwhile, the proportion of peptides in the 500–1000 Da range in the CGL group (53.42%) was higher than that in the CSL group (35.50%), suggesting that intestinal proteases can continuously degrade the large-molecule peptides in the CGL group. This also resulted in the CGL group maintaining a high number of characteristic peptides (161 unique peptides) in the cecum stage. The serum analysis revealed obviously increased collagen peptide counts (205 peptides) and hydroxyproline peptide ratios (93.66%) in the CGL group, with specific peptide segments primarily originating from the cross-linking active sites (Lys644, Gln972). These findings confirm the absorption advantage of the CGL group. In addition, CGL optimized the amino acid absorption pattern by cross-linking modification while maintaining the basic nutritional properties of collagen. The metabolomics results showed that CGL regulated key metabolic pathways such as steroid hormone synthesis, glutathione metabolism and tryptophan metabolic pathway. This study reveals the progressive “gastric degradation - intestinal absorption” mechanism of crosslinked collagen gel. Its unique peptide release pattern and metabolic regulation provide a theoretical basis for developing functional collagen-based products targeting intestinal absorption.

In recent years, chromium-free tanning agents have gained widespread attention as eco-friendly and non-toxic alternatives in the leather industry. However, most commercially available options still suffer from poor stability under wet and heat conditions, lack of antimicrobial properties, and susceptibility to yellowing. Herein, pectin (P) was oxidized by sodium periodate (NaIO₄), green ethylene glycol diglycidyl ether (EGDE) was then used for graft modification, resulting in the successful synthesis of a multifunctional, green oxidized pectin-EGDE (OPE) as a chromium-free tanning agent. Characterization by FTIR, XPS, XRD, and ¹H NMR indicates that OPE has an oxidation value of 68%, epoxide value of 0.34 mol/100 g. Leather tanned with OPE demonstrates remarkably improved properties compared to traditional chromium-free tanning agents (F-90 and TWS), including high thermal stability (shrinkage temperature of 80.5 °C), superior softness (6.3 mm), tensile strength (13.3 MPa), and tear strength (57.3 N/mm). Moreover, the leather tanned with OPE also exhibits significant antimicrobial properties (inhibition zone diameters of 15 mm against S. aureus and 18 mm against E. coli), resistance to yellowing, and biocompatibility. Notably, the biodegradability of the wastewater from OPE tanned leather (BOD₅/COD ≥ 0.3) and its life cycle assessment confirm its unique environmental advantages. Overall, this work uses natural polysaccharides as the raw material to develop a green functional tanning agent, offering an innovative and sustainable solution for advancing the leather industry toward greener development.

Collagenous derivatives (collagen, gelatin, and collagenous hydrolysate (CH)) are extensively used across the food, biomedical, and pharmaceutical industries. Traditionally, these have been sourced from porcine, bovine, and fish due to their ready availability and biocompatibility. However, conventional collagenous derivatives face ongoing challenges regarding sustainability, resource intensity, and socio-cultural perceptions. This has led to the exploration of alternative collagenous derivatives from unconventional sources, with a primary focus on evaluating their potential for yields, extractability, and functional properties, all of which are fundamental for future scale-up and alternative applications. This review summarizes alternative collagenous derivatives from unconventional animals, including amphibians, mollusks, echinoderms, insects, unconventional fish and byproducts, and reptiles. Their structures, extraction techniques, functional properties, and potential applications are comprehensively summarized, showcasing their ability to complement or even surpass conventional sources in specific uses. Additionally, the challenges and prospects for industrial application, emphasizing the sustainability of meeting growing collagen demand and encouraging further research into these promising alternative sources, were discussed. Unconventional collagenous derivatives demonstrate excellent and unique characteristics as alternatives to conventional ones. Type I collagen from amphibians, reptiles, and mollusks had superior thermal stability. Unconventional gelatin and CH also possess various bio-functionalities that can enhance their potential applications. The relatively low extraction yield could be addressed by increasing the concentration of chemicals or extraction time and incorporating green technology without causing an adverse impact on the quality. These findings indicate the potential applications of unconventional collagenous derivatives as food ingredients and supplements.

Environmental and health concerns related to mineral and synthetic tanning agents in leather production are prompting a shift toward sustainable, plant-based alternatives. One group of plant-based tanning agents are the secoiridoids from plants of the Oleaceae family (olive, privet). When their leaves are damaged, secoiridoids are enzymatically deglycosylated to produce aglycones containing aldehyde groups, which are able to cross-link collagen covalently. However, a reliable method to quantify these active aldehyde compounds has been lacking, hindering the application of such tannins. Here, secoiridoid aglycones with aldehyde groups in Olea europaea and Ligustrum vulgare leaf extracts were measured using HPLC-DAD after derivation with 2,4-dinitrophenylhydrazine. Low-temperature extractions (≤40 °C) yielded high aldehyde content (up to 17 mg/g extract), attributed to enzymatic activity, while high-temperature extractions (≥60 °C) preserved the inactive, glycosylated precursors but contained negligible aldehydes due to enzyme denaturation. The cross-linking potential of the extracts was quantified by testing the denaturation temperature and proportion of covalently bound lysine groups of the hide powder treated with endogenously activated Oleaceae extracts. A strong linear relationship was found between aldehyde content and tanning capacity. The most essential aldehyde-containing substances in the extracts as well as the key parameters for efficient extraction were identified. In conclusion, we introduce a new method to accurately measure aldehyde content and assess the cross-linking potential of Oleaceae plant extracts, and expect to support the development of safer, plant-based tannins for the leather industry.