Collagen is an important material for biomedical research, but using mammalian tissue-derived collagen carries the risk of zoonotic disease transmission. Marine organisms, such as farmed tilapia, have emerged as a safe alternative source of collagen for biomedical research. However, the tilapia collagen products for biomedical research are rare, and their biological functions remain largely unexamined. In this study, we characterized a commercial tilapia skin collagen using SDS-PAGE and fibril formation assays and evaluated its effects on skin fibroblast adhesion, proliferation, and migration, comparing it with commercial collagen from rat tails, porcine skin, and bovine skin. The results showed that tilapia skin collagen is a type I collagen, similar to rat tail collagen, and has a faster fibril formation rate and better-promoting effects on cell migration than porcine and bovine skin collagen. We also confirmed its application in a 3D culture for kidney cells\' spherical cyst formation, fibroblast-induced gel contraction, and tumor spheroid interfacial invasion. Furthermore, we demonstrated that the freeze-dried tilapia skin collagen scaffold improved wound closure in a mouse excisional wound model, similar to commercial porcine or bovine collagen wound dressings. In conclusion, tilapia skin collagen is an ideal biomaterial for biomedical research.

OBJECTIVE: Study the possible mechanism and delayed effect of tilapia skin collagen on skin aging for mice.
METHODS: Kunming (KM) mice were randomly divided into the aging model group, the normal group, the positive control group (vitamin E) and the low, medium, high dose tilapia skin collagen groups (2.0, 4.0, 8.0 mg/g). The normal group was only injected with saline at the back and the neck. The other groups were injected subcutaneously with 5% D-galactose and ultraviolet light jointly to establish the aging model. After modeling, the positive control group was treated with a dose of 10% vitamin E once a day, and the low, medium, high dose tilapia skin collagen group was separately applied 2.0, 4.0, 8.0 mg/g of tilapia skin collagen for 40 days. The changes of skin tissue morphology, water content, hydroxyproline (Hyp) content, and superoxide dismutase (SOD) activity in mice were studied at the day 10, 20, 30, 40, 50.
RESULTS: Compared with the normal group, the skin of mice in the aging model group was thinner, looser, and the skin moisture content, Hyp content, SOD activity were all decreased. For mice of the low, medium, high dose tilapia skin collagen group, the thickness of dermis increased, possessing close arrangement, and the moisture content, Hyp content, SOD activity were up-regulated significantly, which effectively alleviated the aging process of skin. The dose of tilapia skin collagen was directly proportional to the anti-aging effect.
CONCLUSIONS: Tilapia skin collagen has an obvious effect on improving skin aging.

There is an urgent need for natural sources of aggregation-induced emission (AIE) materials which have good water solubility, biocompatibility, and can be produced in large quantities. Here, Tilapia skin collagen (Tsc) is a very abundant protein in nature, with solid-phase and solution-state fluorescence emission effect and its multiple applications was explored.Due to Tsc was in high concentration or aggregation state which shown AIE property. This obvious emission can be account for clustering-triggered emission (CTE) mechanism. The photoluminescence property of Tsc not only provide a deeper understanding of the emission characteristics of proteins, but also has important guiding significance for further elucidating the basis of fluorescence properties.

Collagen is widely used in medical field because of its excellent biocompatibility and bioactivity. To date, collagen for biomedical use is always derived from bovine or swine. The purpose of this study was to evaluate collagen-based biomaterials from non-mammalian donors for bone repair. Thus, tilapia skin collagen-hydroxyapatite (T-col/HAp) scaffolds were fabricated in three different proportions and then cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide-N-hydroxysuccinimide (EDC-NHS). The scaffolds were evaluated for their microstructure, chemical and physical properties, mechanical strength and degradability. Then the in vitro responses of bone mesenchymal stem cells (BMSCs) to the scaffolds were investigated in terms of cellular proliferation, differentiation, and mineralization. At last, the scaffolds were implanted into rat skull critical defections to investigate the potential of osteogenic activities. As a result, the pore sizes and the porosities of the scaffolds were approximately 106.67-196.67 μm and 81.5%-66.7%. Pure collagen group showed a mechanical strength of 0.065 MPa, and the mechanical strength was significantly enhanced almost 17 times and 32 times in collagen/HAp ratio 1:4 and 1:9 groups. In vitro studies revealed the most prominent and healthy growth of BMSCs in collagen/HAp ratio 1:4 group. All the scaffolds showed certain osteogenic activities and those loaded with small amount of hydroxyapatite showed the strongest bioactivities. The micro-CT showed that the critical bone defect was almost filled with generated bone 6 months after implantation in collagen/HAp ratio 1:4 group. The biomechanics tests further confirmed the highest generated bone strength was in the collagen/HAp ratio 1:4 group. This study indicated aquatic collagen might be a potential alternative for type I collagen from mammals in bone tissue engineering. The combination of collagen and inorganic materials was also important and appropriate inorganic component loading can achieve both osteogenic quality and osteogenic efficiency to a certain extent.

Guided tissue regeneration (GTR) membranes play a vital role in periodontal surgery. Recently a series of composite electrospun membranes have been fabricated to improve the unexpected biodegradation of collagen-based GTR membranes. However, their tissue integrity needs to be studied in depth. In this study, a bi-layered electrospun membrane (BEM) inspired by \"prodrug\" was fabricated, which contained a dense-layer (BEM-DL) and a potential loose-layer (BEM-LL). The nanofibers of BEM-DL were composed of poly(l-lactic-co-glycolic acid) and tilapia skin collagen (TSC). Whereas the BEM-LL consisted of two types of nanofibers, one was the same as BEM-DL and the other was made from TSC. The morphology, degradation in vitro, cytocompatibility and biocompatibility in rats were investigated with a poly(lactic-co-glycolic acid) electrospun membrane (PLGA) as the negative control. The pore size of BEM-LL soaked for 7 days became larger than the original sample (164.8 ± 90.9 and 52.5 ± 21.0 μm2 , respectively), which was significantly higher (p < .05) than that of BEM-DL and PLGA. The BEM-LL displayed a larger weight loss rate of 82.3 ± 3.6% than the BEM-DL of 46.0 ± 2.8% at day 7 because of the rapid degradation of TSC fibers. The cytocompatibility test demonstrated that L929 cells were only spread on the surface of the BEM-DL while MC3T3-E1 cells grew into the BEM-LL layer. The subcutaneous implantation test further proved that BEM-DL performed as a cellular barrier, whereas BEM-LL was conducive to cell infiltration as deep as 200 μm with reduced fibrous encapsulation. Herein, the BEM inspired by \"prodrug\" is a promising GTR membrane with a property of enhanced tissue integration.

Fish skin collagen hydrolyzate has demonstrated the potent inhibition of dipeptidyl peptidase-IV (DPP-IV), one of the treatments for type-2 diabetes mellitus (type-2 DM), but the precise mechanism is still unclear. This study used in silico method to evaluate the potential of the active peptides from tilapia skin collagen (Oreochromis niloticus) for DPP-IV inhibitor. The methodology includes collagen hydrolysis using BIOPEP, which is the database of bioactive peptides; active peptide selection; toxicity, allergenicity, sensory analysis of active peptides; and binding of active peptides to DPP-IV compared with linagliptin. The result indicated that in silico enzymatic hydrolysis of collagen produced active peptides with better prediction of biological activity than intact collagen. There are 13 active peptides were predicted as non-toxic and non-allergenic, some of which have a bitter, salty, and undetectable taste. Docking simulations showed all active peptides interacted with DPP-IV through hydrogen bonds, van der Waals force, hydrophobic interaction, electrostatic force, π-sulfur, and unfavorable interaction, where WF (Trp-Phe), VW (Val-Trp), WY (Trp-Tyr), and WG (Trp-Gly) displayed higher binding affinities of 0.8; 0.5; 0.4; and 0.3 kcal/mol compared with linagliptin. In this study, we successfully demonstrated antidiabetic type-2 DM potential of the active peptides from tilapia skin collagen. The obtained data provided preliminary data for further research in the utilization of fish skin waste as a functional compound to treat the type-2 DM patients. Alternatively, this treatment can be synergistically combined with the available antidiabetic drugs to improve the insulin secretion of the type-2 DM patients.

There is an urgent need for natural sources of aggregation-induced emission (AIE) materials which have good water solubility, biocompatibility, and can be produced in large quantities. Here, Tilapia skin collagen (Tsc) is a very abundant protein in nature, with solid-phase and solution-state fluorescence emission effect and its multiple applications was explored. Due to Tsc was in high concentration or aggregation state which shown AIE property. This obvious emission can be account for clustering-triggered emission (CTE) mechanism. The photoluminescence property of Tsc not only provide a deeper understanding of the emission characteristics of proteins, but also has important guiding significance for further elucidating the basis of fluorescence properties.

Type I collagen, used as a raw material, plays a pivotal role in the development of medical devices and tissue engineering. Due to the risk of zoonotic transmission and religious constraints for mammalian collagen, fish collagen gains increased attention and is widely seen as an alternative. In this study, two collagen micro/nanofiber materials, self-assembled collagen nanofiber and electrospun collagen nanofiber, were prepared by tilapia skin collagen and their biocompatibility and immunogenicity was thoroughly investigated. The result revealed that the state of tilapia skin collagen in self-assembled collagen nanofiber and electrospun collagen nanofiber was different. The circular dichroism spectrum indicated that collagen in self-assembled collagen nanofiber retained the triple helical structure of the native collagen, while collagen in electrospun collagen nanofiber was denatured into gelatin. Nevertheless, the evaluation according to ISO10993, including tests of cytotoxicity, hemolysis, skin sensitization, acute systemic toxicity, mouse immunization and lymphocyte proliferation, demonstrated good biocompatibility and low immunogenicity for both self-assembled and electrospun collagen nanofiber materials. Overall, the present study highlighted that type I collagen from tilapia skin would be a promising biomaterial for the development of regenerate medical products.