Mechanical Properties of Porcine and Fish Skin-Based Collagen and Conjugated Collagen Fibers

Preparation of films based on reticulated fish gelatin containing garlic essential oil

Agro-industrial co-products, such as fish gelatin, stand out for their capacity in forming biopolymeric films, being biocompatible and non-toxic; however, its hydrophilicity poses a challenge. Essential oils, rich in bioactives, attract research interest aiming to enhance the protective barrier of films and enable their application in packaging. This study produced films based on cross-linked Nile tilapia skin gelatin, incorporating garlic essential oil. Gelatin obtained through partial collagen hydrolysis from the fish skin and cross-linked with gallic acid had hydroxyproline content of 10.02 g 100 g-1 and gel strength of 287 g, which were consistent with other studies. Oil extraction used supercritical CO2 as a solvent and ethanol as a cosolvent, following a factorial experimental design, evaluating the extraction temperature (40 °C and 70 °C) and cosolvent ratio (1:1 and 1:3), with three central points. Extraction was successful, with higher yields on a dry basis at 70 °C (88.35 %), using a 1:1 cosolvent ratio. Films incorporated with oil exhibited lower water vapor permeability (WVP) than those with only cross-linked gelatin (1.59 (g m-1 s-1 Pa-1) 1011). The film with the most suitable tensile strength (19.07 MPa), elongation (120.91 %), and WVP (1.09 (g m-1 s-1 Pa-1) 1011) properties contained garlic oil extracted at the central point (55 °C and 1:2). Thermal analysis indicated increased melting temperatures in films with added oil, suggesting low thermal degradation. These results suggest that garlic oil addition can improve the properties of fish gelatin-based films, making them promising for biodegradable packaging.

A sustainable strategy for generating highly stable human skin equivalents based on fish collagen

Tissue engineered skin equivalents are increasingly recognized as potential alternatives to traditional skin models such as human ex vivo skin or animal skin models. However, most of the currently investigated human skin equivalents (HSEs) are constructed using mammalian collagen which can be expensive and difficult to extract. Fish skin is a waste product produced by fish processing industries and identified as a cost-efficient and sustainable source of type I collagen. In this work, we describe a method for generating highly stable HSEs based on fibrin fortified tilapia fish collagen. The fortified fish collagen (FFC) formulation is optimized to enable reproducible fabrication of full-thickness HSEs that undergo limited contraction, facilitating the incorporation of human donor-derived skin cells and formation of biomimetic dermal and epidermal layers. The morphology and barrier function of the FFC HSEs are compared with a commercial skin model and validated with immunohistochemical staining and transepithelial electrical resistance testing. Finally, the potential of a high throughput screening platform with FFC HSE is explored by scaling down its fabrication to 96-well format.

Lipase-Catalyzed Synthesis of Structured Fatty Acids Enriched with Medium and Long-Chain n-3 Fatty Acids via Solvent-Free Transesterification of Skipjack Tuna Eyeball Oil and Commercial Butterfat

Human milk lipids generally have the maximum long-chain fatty acids at the sn-2 position of the glycerol backbone. This positioning makes them more digestible than long-chain fatty acids located at the sn-1, 3 positions. These unique fatty acid distributions are not found elsewhere in nature. When lactation is insufficient, infant formula milk has been used as a substitute. However, the distribution of most fatty acids ininfant formula milk is still different from human milk. Therefore, structured lipids were produced by the redistribution of medium-chain fatty acids from commercial butterfat (CBF) and n-3 and n-6 long-chain fatty acids from skipjack tuna eyeball oil (STEO). Redistribution was carried out via transesterification facilitated by Asian seabass liver lipase (ASL-L). Under the optimum conditions including a CBF/STEO ratio (3:1), transesterification time (60 h), and ASL-L unit (250 U), the newly formed modified-STEO (M-STEO) contained 93.56% triacylglycerol (TAG), 0.31% diacylglycerol (DAG), and 0.02% monoacylglycerol (MAG). The incorporated medium-chain fatty acids accounted for 18.2% of M-STEO, whereas ASL-L could incorporate 40% of n-3 fatty acids and 25-30% palmitic acid in M-STEO. The 1H NMRA and 13CNMR results revealed that the major saturated fatty acid (palmitic acid) and unsaturated fatty acids (DHA and EPA) were distributed at the sn-2 position of the TAGs in M-STEO. Thus, M-STEO enriched with medium-chain fatty acids and n-3 fatty acids positioned at the sn-2 position of TAGs can be a potential substitute for human milk fatty acids in infant formula milk (IFM).

Assessment of Tilapia Skin Collagen for Biomedical Research Applications in Comparison with Mammalian Collagen

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.

Extraction and Characterization of Human Adipose Tissue-Derived Collagen: Toward Xeno-Free Tissue Engineering

BACKGROUND

Collagen is a key component of connective tissue and has been frequently used in the fabrication of medical devices for tissue regeneration. Human-originated collagen is particularly appealing due to its low immune response as an allograft biomaterial compared to xenografts and its ability to accelerate the regeneration process. Ethically and economically, adipose tissues available from liposuction clinics are a good resource to obtain human collagen. However, studies are still scarce on the extraction and characterization of human collagen, which originates from adipose tissue. The aim of this study is to establish a novel and simple method to extract collagen from human adipose tissue, characterize the collagen, and compare it with commercial-grade porcine collagen for tissue engineering applications.

METHODS

We developed a method to extract the collagen from human adipose tissue under quasi-Good Manufacturing Practice (GMP) conditions, including freezing the tissue, blood removal, and ethanol-based purification. Various techniques, including protein quantification, decellularization assessment, SDS-PAGE, FTIR, and CD spectroscopy analysis, were used for characterization. Amino acid composition was compared with commercial collagen. Biocompatibility and cell proliferation tests were performed, and in vitro tests using collagen sponge scaffolds were conducted with statistical analysis.

RESULTS

Our results showed that this human adipose-derived collagen was equivalent in quality to commercially available porcine collagen. In vitro testing demonstrated high cell attachment and the promotion of cell proliferation.

CONCLUSION

In conclusion, we developed a simple and novel method to extract and characterize collagen and extracellular matrix from human adipose tissue, offering a potential alternative to animal-derived collagen for xeno-free tissue engineering applications.

Plant Protein-Peptide Supramolecular Polymers with Reliable Tissue Adhesion for Surgical Sealing

The fusion of protein science and peptide science opens up new frontiers in creating innovative biomaterials. Herein, a new kind of adhesive soft materials based on a natural occurring plant protein and short peptides via a simple co-assembly route are explored. The hydrophobic zein is supercharged by sodium dodecyl sulfate to form a stable protein colloid, which is intended to interact with charge-complementary short peptides via multivalent ionic and hydrogen bonds, forming adhesive materials at macroscopic level. The adhesion performance of the resulting soft materials can be fine-manipulated by customizing the peptide sequences. The adhesive materials can resist over 78 cmH2 O of bursting pressure, which is high enough to meet the sealing requirements of dural defect. Dural sealing and repairing capability of the protein-peptide biomaterials are further identified in rat and rabbit models. In vitro and in vivo assays demonstrate that the protein-peptide adhesive shows excellent anti-swelling property, low cell cytotoxicity, hemocompatibility, and inflammation response. In particular, the protein-peptide supramolecular biomaterials can in vivo dissociate and degrade within two weeks, which can well match with the time-window of the dural repairing. This work underscores the versatility and availability of the supramolecular toolbox in the easy-to-implement fabrication of protein-peptide biomaterials.

The Flexible Armor of Chinese Sturgeon: Potential Contribution of Fish Skin on Fracture Toughness and Flexural Response

Fish skin is a biological material with high flexibility and compliance and can provide good mechanical protection against sharp punctures. This unusual structural function makes fish skin a potential biomimetic design model for flexible, protective, and locomotory systems. In this work, tensile fracture tests, bending tests, and calculation analyses were conducted to study the toughening mechanism of sturgeon fish skin, the bending response of the whole Chinese sturgeon, and the effect of bony plates on the flexural stiffness of the fish body. Morphological observations showed some placoid scales with drag-reduction functions on the skin surface of the Chinese sturgeon. The mechanical tests revealed that the sturgeon fish skin displayed good fracture toughness. Moreover, flexural stiffness decreased gradually from the anterior region to the posterior region of the fish body, which means that the posterior region (near the tail) had higher flexibility. Under large bending deformation, the bony plates had a specific inhibition effect on the bending deformation of the fish body, especially in the posterior region of the fish body. Furthermore, the test results of the dermis-cut samples showed that the sturgeon fish skin had a significant impact on flexural stiffness, and the fish skin could act as an external tendon to promote effective swimming motion.

Research on essential performance of oxidized chitosan-crosslinked acellular porcine aorta modified with bioactive SCPP/DOPA for esophageal scaffold with enhanced mechanical strength, biocompatibility and anti-inflammatory

Acellular porcine aorta (APA) is an excellent candidate for an implanted scaffold but needs to be modified with appropriate cross-linking agent to increase its mechanical property and storage time in vitro as well as to give itself some bioactivities and eliminate its antigenicity for acting as a novel esophageal prosthesis. In this paper, a polysaccharide crosslinker (oxidized chitosan, OCS) was prepared by oxidizing chitosan using NaIO₄ and further used to fix APA to prepare a novel esophageal prosthesis (scaffold). And then the surface modification with dopamine (DOPA) and strontium-doped calcium polyphosphate (SCPP) were performed one after another to prepare DOPA/OCS-APA and SCPP-DOPA/OCS-APA to improve the biocompatibility and inhibit inflammation of the scaffolds. The results showed that the OCS with a feeding ratio of 1.5:1.0 and a reaction time of 24 h had a suitable molecular weight and oxidation degree, almost no cytotoxicity and good cross-linking effect. Compared with glutaraldehyde (GA) and genipin (GP), OCS-fixed APA could provide a more suitable microenvironment for cell proliferation. The vital cross-linking characteristics and cytocompatibility of SCPP-DOPA/OCS-APA were evaluated. Results suggested that SCPP-DOPA/OCS-APA exhibited suitable mechanical properties, excellent resistance to enzymatic degradation/acid degradation, suitable hydrophilicity, and the ability to promote the proliferation of Human normal esophageal epithelial cells (HEECs) and inhibit inflammation in vitro. In vivo tests also confirmed that SCPP-DOPA/OCS-APA could diminish the immunological response to samples and had a positive impact on bioactivity and anti-inflammatory. In conclusion, SCPP-DOPA/OCS-APA could act as an effective, bioactive artificial esophageal scaffold and be expected to be used for clinical in the future.

Collagen Derived from Fish Industry Waste: Progresses and Challenges

Fish collagen garnered significant academic and commercial focus in the last decades featuring prospective applications in a variety of health-related industries, including food, medicine, pharmaceutics, and cosmetics. Due to its distinct advantages over mammalian-based collagen, including the reduced zoonosis transmission risk, the absence of cultural-religious limitations, the cost-effectiveness of manufacturing process, and its superior bioavailability, the use of collagen derived from fish wastes (i.e., skin, scales) quickly expanded. Moreover, by-products are low cost and the need to minimize fish industry waste's environmental impact paved the way for the use of discards in the development of collagen-based products with remarkable added value. This review summarizes the recent advances in the valorization of fish industry wastes for the extraction of collagen used in several applications. Issues related to processing and characterization of collagen were presented. Moreover, an overview of the most relevant applications in food industry, nutraceutical, cosmetics, tissue engineering, and food packaging of the last three years was introduced. Lastly, the fish-collagen market and the open technological challenges to a reliable recovery and exploitation of this biopolymer were discussed.

Adulteration Detection of Edible Bird’s Nests Using Rapid Spectroscopic Techniques Coupled with Multi-Class Discriminant Analysis

Edible bird’s nests (EBNs) are vulnerable to adulteration due to their huge demand for traditional medicine and high market price. Presently, there are pressing needs to explore field-deployable rapid screening techniques to detect adulteration of EBNs. The objective of this study is to explore the feasibility of using a handheld near-infrared (VIS/SW-NIR) spectroscopic device for the determination of EBN authenticity against the benchmark performance of a benchtop mid-infrared (MIR) spectrometer. Forty-nine authentic EBNs from the different states in Malaysia and 13 different adulterants (five types) were obtained and used to simulate the adulteration of EBNs at 1, 5 and 10% adulteration by mass (a total of 15 adulterated samples). The VIS/SW-NIR and MIR spectra collated were subsequently processed, modelled and classified using multi-class discriminant analysis. The VIS/SW-NIR results showed 100% correct classification for the collagen and nutrient agar classes in authenticity classification, while for the other classes, the lowest correct classification rate was 96.3%. For MIR analysis, only the karaya gum class had 100% correct classification whilst for the other four classes, the lowest rate of correct classification was at 94.4%. In conclusion, the combination of spectroscopic analysis with chemometrics can be a powerful screening tool to detect EBN adulteration.