Unlocking the Power of Marine Collagen as an Eco-Friendly Biomaterial

Biomaterials have gained significant attention in recent times because of their distinct properties and versatility in meeting application needs. These chemically unique macromolecules include polyesters, polymeric materials, polysaccharides, polypeptides, and polynucleotides. They can be obtained from a variety of easily accessible, environmentally acceptable materials that are both biocompatible and biodegradable, which makes them perfect for usage in a variety of therapeutic and diagnostic processes. Collagen is a well-known biomaterial that is naturally high in polymers. It has rich supplies and remarkable biological performances, which make it perfect for alleviating resource restrictions, cutting down on environmental waste, and promoting sustainable progress.

Collagen is the protein that is most common in the human body and has a crucial structural role in connective tissues such as bones, tendons, ligaments, and skin. It gives different tissues and organs flexibility, strength, and support. The triple helix structure of collagen is made up of extended chains of amino acids, mainly glycine, proline, and hydroxyproline. Collagen's characteristic toughness and strain resistance are attributed to this structure.

There are currently 29 different forms of collagen identified, with differences in distribution, morphological structure, amino acid residue sequence, and biophysiological characteristics. Collagen can be mainly categorized into fibrillar collagen, microfibrillar collagen, fibril-associated collagen with interrupted triple helix (FACIT), short-chain collagen, anchoring collagen, transmembrane collagen, and basement membrane collagen based on their structural and supramolecular organization, as shown in Table 1. The many functions that the collagen superfamilies perform inside particular body tissues give them the opportunity to engage in a variety of biological activities.

Structure of Collagen

Collagen has a very distinct and well-organized structure with a hierarchical organization that gives tissues flexibility and strength. Collagen's main structural components are long chains of amino acids, mainly glycine, proline, and hydroxyproline. Collagen has a distinct spatial structure and multi-hierarchical organization that are derived from the special makeup and arrangement of proteins. Gly-X-Y is the common repeating amino acid sequence found in collagen, where X and Y are frequently proline and hydroxyproline, respectively.

The polypeptide chains create a left-handed helical helix in secondary structure. Although they are the foundation for the next level of structure, these individual helices are not extremely durable on their own.

Three of these left-handed helices coil together to produce a right-handed triple helix, which is the basic building block of collagen and is referred to as a tropocollagen molecule when discussing tertiary structure. Hydrogen connections between amino acids, especially the hydroxyl group of hydroxyproline, stabilize the triple helix and aid in keeping the helices in place.

Tensile strength in quaternary structure is provided by collagen fibrils, which are long, thin structures made up of many tropocollagen molecules aligning and binding together. Collagen fibers are created by arranging these fibrils into parallel bundles; the size and orientation of these fibers varies according on the type of tissue (e.g., skin, tendons, cartilage). As collagen ages, covalent cross-links between its molecules develop in fibrils, strengthening and stabilizing the structure even more against mechanical stress.

Depending on the tissue, collagen fibers are arranged into bigger structures during the formation of super-molecular structures. For instance, the fibers in tendons are arranged in parallel to withstand stretching stresses, whereas the fibers in skin are woven in a mesh-like pattern to provide flexibility.

Marine Sources of Collagen

Over the past ten years, researchers have concentrated on investigating various sources and improving the conditions for collagen extraction due to the growing interest in highlighting industrial by-products. Although the most common sources of collagen are still bovine hide, cattle bones, pork, and pig skins, there is an increasing trend in the commercial use of collagen from non-mammalian species, particularly marine sources. The use of collagen derived from these sources has been restricted due to concerns about infectious diseases such as transmissible spongiform encephalopathy, bovine spongiform encephalopathy, and foot and mouth disease. A significant amount of the world's population is also impacted by religious constraints. On the other hand, marine collagen shares physicochemical characteristics with mammalian collagen, but it has several unique benefits, including a lower denaturation weight and temperature, a decreased risk of disease transmission, easier extraction techniques, and fewer inflammatory reactions.

And also, Three α-chains (α1-α1-α2) of roughly 1000 amino acid residues or multipeptide α-chains make up marine collagen molecules. These α-chains are organized bilaterally and vertically in a periodic fiber structure to produce a stable triple helix shape. The quaternary structure and essential amino acid composition of marine collagen are identical to those of terrestrial mammalian collagen, which is reflected in the great stability of the distinctive triple helix area. Despite these similarities, the greater complexity and diversity of the marine environment lead to a variety of marine collagen structures that are influenced by a number of factors, including species, origin, growth cycle, season, and environment. The structure and composition of marine collagen differ slightly from that of collagen from terrestrial animals as a result.

Current study reports state that physical-aided, enzymatic, acidic, and ultrasound-assisted procedures are used in collagen extraction and separation processes from a variety of marine sources. To increase production and lower pollution, researchers have also developed eco-friendly techniques as deep eutectic solvent extraction, supercritical fluid extraction, and extrusion-hydro-extraction. Separation difficulty, extraction rate, purity, and structural integrity are all impacted by the distribution of collagen fibers, binding tightness, and degree of cross-linking with other components.

Collagens from various marine sources, including, sea cucumbers, mollusks, sponges, crustaceans, jellyfish, and particularly fish, have been extracted and characterized to varying extents.

01. Sea cucumber

Sea cucumbers, which belong to the phylum Echinodermata and are classified as invertebrates in the class Holothuroidea, are a traditional meal in China, Korea, Japan, and some regions of Southeast Asia. These marine invertebrates are found in more than 1250 species worldwide, and many of them have important nutritional and bioactive roles in addition to being edible. Sea cucumber species and growing conditions can affect their nutritional value and chemical makeup. The sea cucumber's main edible portion is its body wall, where collagen plays a vital role and makes up around 70% of its total protein. A special type of changeable collagenous tissue, the sea cucumber's body wall is made up of fundamental structural elements like collagen, proteoglycan, and glycoprotein. Insoluble collagen fibrils make up the majority of the total proteins in the body wall, while these components combine to form collagen fibrils, microfibrils, and collagen fibers. Mostly found in sea cucumbers, type I collagen is essential to the food quality of sea cucumbers and their processed products (such as freeze-dried, microwave-dried, salt-dried, boiled-dried, and ready-to-eat items), especially their texture.

02. Crustaceans

Crustaceans are a diverse group of marine invertebrates that include prawns, mantis shrimp, lobsters, crabs, prawns, krills, crabs, copepods, and ostracods. They are members of the Phylum Arthropoda. Large amounts of crustaceans are produced worldwide. Myofibrillar proteins, along with sarcoplasmic proteins, make up the majority of crustacean muscles, although collagen makes up a very minor portion of the total protein content. Despite having low content percentages ranging from 0.015% to 0.4878%, the collagen had type I properties resembling those of vertebrate muscles. There may be notable differences in collagen types and collagen content between various crustaceans.

03. Marine sponges

There are over 220 species of marine sponges, also known as poriferans, which are a diverse collection of filter-feeding benthic invertebrates that are primarily found in saltwater but can also be found sometimes in freshwater. They are members of the phylum Porifera. In contrast to other animal groupings, sponges lack true organs and tissues and have a simple organization. They are made up of a layer of epithelial cells, such as choanocytes and pinacocytes, encircling the gelatinous interior tissue (mesohyl). Known as spongin or spongin-like collagen, these cells are incorporated into a complex 3-D matrix network that is rich in collagen. Spongin, a collagenous protein present in some sponges' exoskeleton, creates a complex fibrous network that gives the sponge its flexural rigidity. However, because of the great diversity within this sponge family, its exact and comprehensive chemical composition is still unknown, which presents a significant obstacle for further clarification.

04. Jellyfish

For more than 1700 years, jellyfish, also called "medusae," have been a traditional food source in several Asian countries, particularly China and Japan, because of its medicinal and nutritional benefits. Jellyfish is a perfect, healthful seafood product because of its low fat and calorie content, as well as its plenty of collagenous protein and minerals. Compared to collagen from terrestrial animals, jellyfish collagen may have fewer immunogenic and inflammatory reactions, as well as fewer biological pollutants and contaminants.

05. Mollusca

With more than 120,000 species, the phylum Mollusca exhibits significant morphological, ecological, and chemical diversity. These species include squids (Doryteuthis singhalensis), mussels (Mytilus chilensis), scallops (Patinopecten yessoensis), oysters (Crassostrea gigas), and clams (Meretrix meretrix). Mollusk species, which are found in temperate, tropical, and polar environments, can be distinguished by the size and form of their bodies. 80% of the fleshy material of mollusks is fit for human consumption, making them high in protein. Mollusks have a high water content in their edible parts and a low fat content in their dry bulk, which is made up of proteins and micro/macro minerals. Studies have revealed that because of the wide variety within this family of organisms, the bio-physiological characteristics, morphological structure, and molecular composition of mollusk collagen have not been completely explored. Because of the wide variety within this mollusk family, research has revealed that the bio-physiological characteristics, morphological structure, and molecular composition of mollusk collagen have not yet been thoroughly understood. However, several kinds of studies have shown the possible presence of type I collagen in clam shells, byssus, squid, and cephalopods, suggesting their appropriateness as possible sources of raw materials for uses in food preparation.

06. Fish

About 60–70% of fresh bone is made up of inorganic materials, namely calcium phosphate and hydroxyapatite, while the remaining 30% is made up of organic collagen. Fish collagen has a lower denaturing temperature than mammalian collagen because of its unique amino acid composition, which includes low levels of hydroxyproline, proline, and glycine. Caruso claims that because of their small particle size and low molecular weight, fish collagens from skin, bone, cartilage, and scales have higher bioavailability than collagen from pigs or cows. They also exhibit improved absorption efficiency (up to 1.5 times) and faster circulatory circulation. The structural properties of fish collagen have been identified through physicochemical characterization and amino acid analysis. Proline and hydroxyproline amino rings, which provide conformational stability and impose strict restrictions on rotational movement along the N-Cα bond in the backbone, are significantly different in collagen from different fish species, according to research on their amino acids. Fish collagen's thermal stability can change depending on the relative amounts of proline and hydroxyproline, two amino acids that are strongly correlated with the species' body temperature and living conditions. In contrast to collagen from warm-blooded terrestrial animals, fish collagen, which is influenced by cooler environments, usually exhibits lower amino acid levels and thermal stability.

Powerful Biological Performances of Collagen

Collagen has undergone multiple processing steps to enhance cell growth, proliferation, differentiation, and activity in order to achieve its powerful biological implications.

Antioxidant Ability of Collagen

Different types of collagen have a wide range of antioxidant properties. For example, Collagen derived from the skin of Silver Pomfret (Pampus argenteus) and Crimson Snapper (Lutjanus erythropterus) has ferric-reducing properties in addition to scavenging ability against 2,2-diphenyl1-picrylhydrazyl (DPPH) and nitric oxide radicals.

Generally, Collagen has antioxidant properties because it can scavenge free radicals, which are unstable chemicals that can harm the body's proteins, tissues, and cells by causing oxidative stress. Certain amino acids including glycine, proline, and hydroxyproline are found in collagen, especially hydrolyzed collagen (collagen that has been broken down into smaller peptides). By eliminating oxidative stress and free radicals, these amino acids are believed to support collagen's antioxidant properties.

Inhibitory Activity

Collagen's inhibitory activity refers to its ability to slow down or prevent certain biological processes, particularly in relation to enzymes or harmful molecules. Generally, Collagen may provide therapeutic benefits by inhibiting a number of enzymes. And also, it is important in various health and medical contexts, such as anti-inflammatory responses, protection against tissue degradation, and antimicrobial effects.

Antitumor Activity

Tumors are abnormal masses of tissue that form when cells in the body grow and divide uncontrollably. In cancer treatment, taking of fish-derived collagen may be the potential antitumor treatment because the low molecular weight of collagen peptides exhibit antimicrobial property.

Anti?freeze activity

Anti-freeze collagen molecules can improve tissue and blood preservation and shield cell membranes to maintain a range of biological processes. By regulating the creation of ice and constantly changing their conformation to get around steric challenges, these molecules exhibit anti-freeze properties. Scientists have recently created a collagen-based conductive hydrogel that is biocompatible and resistant to extremely low temperatures (-60 °C). This hydrogel's ability to precisely track the motions of the human body demonstrates its potential as a cutting-edge biomaterial for the development of biomimetic e-skin.

Regulating biological activities

In the body, collagen can interact with a variety of substances, including platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF), to perform a wide range of biological functions. In order to improve treatment efficacy by guiding VEGF localization to wounded regions, collagen was used due to its high binding affinity for growth factors. Collagen production is also controlled by specific circumstances. Connective tissue growth factor may encourage the development of type I collagen in animals by secreting the cloned ctgf gene into a cell culture medium. Additionally, bone marrow mesenchymal stromal cells' (BMSCs') immunomodulatory potential has been observed to be retained by isolated collagen derived from fish.

Involving the tissue recovery

For many complex tissue injury situations, collagen may be a good therapeutic alternative. As example, overproduction of type I collagen in early-stage osteoarthritis may eventually cause cartilage degradation and the degeneration of collagen II fibers. A hydrogel made of type I collagen combined with sodium alginate and stromal cell-derived factor-1 may serve as a vehicle for BMSCs to treat severe traumatic brain injuries, therefore reducing motor and cognitive impairment. Because the scaffold was highly biocompatible, it decreased brain lesions and neuronal cell death while also reducing inflammation. Scaffold's strong biocompatibility allows it to mitigate neuroinflammation and minimize brain lesions and neuronal cell death. Collagen is derived from biological tissues and can be essential in some parts of the human body, such as generating the fundamental mineralized structure that supports the mechanical strength of bone tissue.

Extraction methods of Collagen

Two crucial processes are required for the extraction of collagen because of its strong structure and low water solubility: (a) raw material pretreatment; and (b) collagen extraction. The raw material is cleaned, dehydrated, degreased, and decalcified during the pretreatment phase. The use of degreasing solutions, enzymatic digestion and lipase degreasing, combined salt solution, and organic solution extraction are the four most often used degreasing techniques. Some samples may contain non-collagenous proteins, lipids, and colors; at this point, NaOH, alcohols (ethanol or butyl alcohol), and oxygen peroxide are usually used to eliminate them. Furthermore, collagen extraction from mineral-rich bodily components, including cartilage, is more effective when the raw material is demineralized with HCl or EDTA prior to extraction.

There are different methods designed for collagen extraction from marine sources are, Acidic extraction, Enzymatic extraction, Deep eutectic solvent extraction, Supercritical fluid extraction, Extrusion?hydro?extraction, Salt solubilization extraction and Physical?aided extraction. Generally, Acidic and enzymatic extraction are commonly used, where acids or enzymes break down fish or marine waste to release collagen. Deep eutectic solvent extraction uses environmentally friendly solvents for efficient recovery, while supercritical fluid extraction applies pressurized CO2 for a high-purity collagen extract. Extrusion-hydro-extraction combines heat and pressure, salt solubilization employs salts to dissolve collagen, and physical-aided extraction uses techniques like ultrasound or microwave assistance to enhance yield. Each method offers unique benefits, often selected based on desired collagen properties and applications.

Applications of Marine-based Collagen

Marine-based collagen has a wide range of applications across several industries, including:

1. Cosmetics and Skincare - Used in anti-aging creams, moisturizers, and serums to improve skin elasticity and hydration.
2. Nutraceuticals and Supplements - Consumed as capsules or powders for joint, bone, and skin health benefits.
3. Medical and Biomedical - Utilized in wound dressings, tissue engineering, and drug delivery systems due to its biocompatibility.
4. Food and Beverages - Added as a protein source in functional foods, beverages, and edible films.
5. Pharmaceuticals - Applied in drug encapsulation and as a carrier for slow-release medication systems.
6. Agriculture - Used as a bioactive additive in animal feed to promote growth and health.
7. Food packaging materials - Collagen-based packaging materials serve as excellent barriers to moisture and oxygen due to their tightly packed, ordered covalent-bonded network structure.

Future Directions of Marine-based Collagen

Due to its fascinating physicochemical and functional characteristics, marine collagen is quickly becoming more and more accepted worldwide. It has enormous potential for use in a wide range of food applications. Using marine collagen in its natural state has shown promise in improving films' biodegradability and antioxidative/antimicrobial qualities, particularly in those that use Pickering emulsions. Marine collagen films do, however, present certain difficulties, including brittleness, low mechanical strength, high water solubility, and enhanced water vapour permeability. The lower denaturation temperature of collagen, especially that derived from cold-water species, is a significant disadvantage that impacts both processing conditions and film qualities.

The increasing demand from consumers for natural and ecological components promises well for marine-based collagen and related products. However, advancements in extraction techniques are expected, which will improve sustainability, yield, and purity. Furthermore, as the bioactive qualities of marine collagen are further studied, new uses in fields like medication delivery, regenerative medicine, and even biodegradable packaging might surface. This tendency fits in with a larger trend towards ecologically friendly items and sustainable sources.

References

https://link.springer.com/article/10.1186/s42825-024-00152-y

https://link.springer.com/article/10.1186/s42825-023-00127-5

Article by,

Wimansa Wijesinghe