Technical note on the isolation and characterization of collagen from fish waste material

Delivery of bone morphogenetic protein-2 by crosslinking heparin to nile tilapia skin collagen for promotion of rat calvaria bone defect repair

Collagen has been widely used as a biomaterial for tissue regeneration. At the present, aqua-collagen derived from fish is poorly explored for biomedical material applications due to its insufficient thermal stability. To improve the bone repair ability and thermal stability of fish collagen, the tilapia skin collagen was crosslinked by EDC/NHS with heparin to bind specifically to BMP-2. The thermal stability of tilapia skin collagen crosslinked with heparin (HC-COL) was detected by differential scanning calorimetry (DSC). Cytotoxicity of HC-COL was assessed by detecting MC3T3-E1 cell proliferation using CCK-8 assay. The specific binding of BMP-2 to HC-COL was tested and the bioactivity of BMP-2-loaded HC-COL (HC-COL-BMP-2) was evaluated in vitro by inducing MC3T3-E1 cell differentiation. In vivo, the bone repair ability of HC-COL-2 was evaluated using micro-CT and histological observation. After crosslinking by EDC/NHS, the heparin-linked and the thermostability of the collagen of Nile Tilapia were improved simultaneously. HC-COL has no cytotoxicity. In addition, the binding of BMP-2 to HC-COL was significantly increased. Furthermore, the in vitro study revealed the effective bioactivity of BMP-2 binding on HC-COL by inducing MC3T3-E1 cells with higher ALP activity and the formation of mineralized nodules. In vivo studies showed that more mineralized and mature bone formation was achieved in HC-COL-BMP-2 group. The prepared HC-COL was an effective BMP-2 binding carrier with enough thermal stability and could be a useful biomaterial for bone repair.

Animal by-products collagen and derived peptide, as important components of innovative sustainable food systems-a comprehensive review

In 2020, the world's food crisis and health industry ushered into a real outbreak. On one side, there were natural disasters such as the novel coronavirus (2019-nCoV), desert locusts, floods, and droughts exacerbating the world food crisis, while on the other side, the social development and changes in lifestyles prompted the health industry to gradually shift from a traditional medical model to a new pattern of prevention, treatment, and nourishment. Therefore, this article reviews animal by-products collagen and derived peptide, as important components of innovative sustainable food systems. The review also considered the preparation, identification, and characterization of animal by-product collagen and collagen peptides as well as their impacts on the food system (including food processing, packaging, preservation, and functional foods). Finally, the application and research progress of animal by-product collagen and peptide in the food system along with the future development trend were discussed. This knowledge would be of great significance for a comprehensive understanding of animal by-product collagen and collagen peptides and would encourage the use of collagen in food processing, preservation, and functional foods.

Upgrading of marine (fish and crustaceans) biowaste for high added-value molecules and bio(nano)-materials

Currently, the Earth is subjected to environmental pressure of unprecedented proportions in the history of mankind. The inexorable growth of the global population and the establishment of large urban areas with increasingly higher expectations regarding the quality of life are issues demanding radically new strategies aimed to change the current model, which is still mostly based on linear economy approaches and fossil resources towards innovative standards, where both energy and daily use products and materials should be of renewable origin and 'made to be made again'. These concepts have inspired the circular economy vision, which redefines growth through the continuous valorisation of waste generated by any production or activity in a virtuous cycle. This not only has a positive impact on the environment, but builds long-term resilience, generating business, new technologies, livelihoods and jobs. In this scenario, among the discards of anthropogenic activities, biodegradable waste represents one of the largest and highly heterogeneous portions, which includes garden and park waste, food processing and kitchen waste from households, restaurants, caterers and retail premises, and food plants, domestic and sewage waste, manure, food waste, and residues from forestry, agriculture and fisheries. Thus, this review specifically aims to survey the processes and technologies for the recovery of fish waste and its sustainable conversion to high added-value molecules and bio(nano)materials.

Collagen/Chitosan Complexes: Preparation, Antioxidant Activity, Tyrosinase Inhibition Activity, and Melanin Synthesis

Bioactive collagen/chitosan complexes were prepared by an ion crosslinking method using fish skin collagen and chitosan solution as raw materials. Scanning electron microscopy observation confirmed that the collagen/chitosan complexes were of a uniform spherical shape and uniform particle size. The complexes were stable at different pH values for a certain period of time through swelling experiments. Differential scanning calorimetry (DSC) showed the collagen/ chitosan complexes were more stable than collagen. X-ray diffraction (XRD) showed that the complexes had a strong crystal structure, and Fourier transform infrared spectroscopy (FTIR) data revealed the changes in the secondary structure of the protein due to chitosan and TPP crosslinking. The content of malondialdehyde (MDA) in the complex treatment group was considerably lower, but the content of SOD was significantly higher than that of the collagen group or chitosan group. In addition, the collagen/chitosan complexes could considerably reduce melanin content, inhibit tyrosinase activity, and down-regulate tyrosinase mRNA expression. In conclusion, the collagen/chitosan complexes were potential oral protein preparation for antioxidant enhancement and inhibiting melanin synthesis.

Extraction and characterization of collagen from the skin of Pterygoplichthys pardalis and its potential application in food industries

The primary objective of this study was to extract collagen from underutilized fish species owing to its cost effective nature and also its ability to address the demand of type I collagen arising from food and pharmaceutical industries. Acid and pepsin soluble collagen (ppASC and ppPSC) were extracted from the skin of sucker catfish (Pterygoplichthys pardalis) with a yield of 19.6 and 23.8% on wet weight basis respectively. The same were characterized and confirmed as type I collagen by SDS-PAGE, FTIR and UV-Vis spectroscopy, amino acid analysis, and Zeta potential. Taking into consideration the application of collagen in food industry, a food product was developed by incorporating with fresh cheese. This fortification was found to be acceptable and had not altered the taste, odor and other sensory properties of the product.

Physicochemical properties of acid- and pepsin-soluble collagens from the cartilage of Siberian sturgeon

To look for the collagen alternatives of mammalian cartilages from aquatics and their by-products, acid-soluble collagen (ASC-SC) and pepsin-soluble collagen (PSC-SC) were extracted from cartilages of Siberian sturgeon (Acipenser baerii) with yields of 27.13 ± 1.15 and 14.69 ± 0.85% on dry weight basis. ASC-SC and PSC-SC had glycine as the major amino acid with the contents of 326.8 and 327.5 residues 1000 residues^-1, and their contents of proline and hydroxyproline were 205.9 and 208.0 residues 1000 residues^-1. ASC-SC and PSC-SC comprised type I collagen ([α1(I)]₂α2(I)) and type II collagen ([α1(II)]₃) on the literatures and results of amino acid composition, SDS-PAGE pattern, UV, and FTIR spectra. Meanwhile, FTIR spectra data indicated that there were more hydrogen bonds in ASC-SC and more intermolecular crosslinks in PSC-SC. The maximum transition temperature (T_max) of the ASC (28.3 °C) and PSC (30.5 °C) was lower than those of collagens from mammalian cartilages (> 37 °C). ASC-SC and PSC-SC showed high solubility in the acidic pH ranges and the solubility decreased in the presence of NaCl at concentrations above 3%. Zeta potential studies indicated that both ASC-SC and PSC-SC exhibited a net zero charge at pH 6.30 and 6.32. SEM results indicated that ASC-SC and PSC-SC presented irregular dense sheet-like film linked by random-coiled filaments. Therefore, collagens from Siberian sturgeon cartilages might be the suitable alternatives of the collagens of mammal cartilages as functional ingredient to treat some diseases.

Extraction and characterization of collagen hydrolysates from the skin of Rana chensinensis

The production of Hasma generates plentiful non-edible by-products in China and Central Asia. As one of main by-products, the skin of Rana chensinensis is discarded as waste without utilization. In this work, R. chensinensis skin collagen (RCSC) hydrolysates were extracted using pepsin under acidic conditions. The yield of RCSC is 15.1% (w/w). Amino acid analysis revealed that RCSC contained glycine (204.5/1000 residues) and imino acids (182/1000 residues). RCSC exhibited high solubility in acidic pH (1-4) and low NaCl concentrations (< 2%, w/v). Differential scanning calorimetry indicated that the denaturation temperature of RCSC was 33.5 °C. Scanning electron microscopy analysis confirmed their well-defined fibril morphologies. The results indicated that the skin of R. chensinensis is an alternative source of collagen hydrolysates, and RCSC can serve as a potential source applying in foodstuff and medical industry.

Rapid detection of collagens using a closed-tube LAMP method

Identification methods of collagens and gelatins have been studied many years due to religious and food safety issues. Some researchers detected the collagen while others took up their study based on DNA at the first time. In this work, we used a closed-tube loop-mediated isothermal amplification (LAMP) technique to differentiate collagen and gelatin samples. DNA was extracted by DNeasy mericon Food Kit and was dissolved in 30 µl elution buffer, optimum concentration of Mg²⁺, deoxyribonucleoside triphosphates(dNTPs), betaine in LAMP reaction is 6.0 mmol/L, 2.0 mmol/L, and 0.8 mmol/L, respectively. After LAMP reaction, samples being detected changed their initial color to green, others' were colorless or brown slightly. The research offered a simple, fast detection technique to differentiate collagen and gelatin samples derived from porcine, bovine and channel catfish (Ictalurus punctatus) , the collagens' species can be determined by color variation in reaction tubes within two hour.

Differentiating collagens based on mitochondrion 12SrRNA gene

Aquatic collagens are one of the main collagens sold in the market due to superior physicochemical and biological activities. In this work, the species of three types of aquatic and commercial collagens were identified by molecular biotechnology. After isolating DNA from bovine, porcine and three types of aquatic animals, DNA was dissolved in a storage buffer. The animals' mitochondrion 12SrRNA sequences were downloaded from the GenBank database, and three pairs of primers that can be used to detect the aquatic collagens were designed by Primer Premier 6 and evaluated by Oligo 7. Analysis of the polymerase chain reaction and agarose electrophoresis showed that the fragments were 440, 307, 112 and 270bp, respectively, thereby enabling successful detection of the collagen species. Results indicate that PCR-based detection methods can also suitably trace the species of aquatic collagens.