1.3.1 Collagen
Collagen is a high molecular weight proteinaceous biomaterial, component of connective tissues of humans, vertebrates and invertebrates. The shape and structural properties of collagen are established by triple helix domain. Collagens are divided into five different groups based on their structure, function, location and other characteristics. Type I and V collagen group is allied with bone, dermis, tendon, ligaments, cornea and Type II cartilage is associated with cartilage, nucleus pulposus, vitreous body and Type III is obtained from vessel wall, skin, reticular fibers of lung, liver and spleen and Type IV in basement membranes.
Collagen extracted from calfskin and bones are the primary sources of industrial collagen and have a high risk of bovine spongiform encephalopathy. To overcome these problems, related to vertebrate collagen, alternative of marine collagen from skin, bones, fin and scales of sponges and jellyfishes has been provided. Marine collagen from Ircinia fusca shows similarity with type I human collagen and other marine sponges Chondrosia reniformis collagen resembles type IV human collagen (Panagiotis, 2015). It shows that marine collagen is having similarities to human collagen and safer alternatives to the potential harmful bovine-originated collagen. Marine collagen can be recovered from marine vertebrates, algae, and invertebrates including jellyfish, sea urchin, Octopus, Squid, Cuttlefish, sea anemone, prawn, starfish (Barzideh et al., 2014; Jankangram et al., 2016; Langasco et al., 2017).
Collagen from marine origin has many advantages over higher vertebrate collagen. It is pure, safe, thermostable, with interconnected porosity, and has higher denaturation temperature due to more cross-linking (Panagiotis, 2015). Collagen of Type I is paramount and has huge applications in biomedical science. Collagen can be structurally converted into porous sheets and gels. Collagen has a wide application in cosmetics, drug delivery, surgery, bio-prosthetic implants, food supplements, and tissue engineering. Collagen appears as a potential biomaterial as scaffold in corneal, wound healing, dental, vascular tissue, and corneal damage tissue engineering. Chondrosia reniformis collagen has an application in preparation of moisturizers. There is a good evidence for the application of collagen biomaterials in drug delivery of target drugs to specific body parts (Patra et al., 2018).
Though collagen has some disadvantages as it can interact with cells and alter its growth or movement. To overcome this problem in collagen scaffolds, it is crosslinked with another suitable material. 3D printed fish collagen scaffold shows biocompatibility with human mesenchymal cells and fibroblast.
1.3.2. Lectins :
Lectins are the diverse group of carbohydrate-binding proteins that bind through high affinity and specific molecular sites. These lectins interact reversibly with high specificity to mono or oligosaccharides through non-covalent linkages. Lectins can recognize and attach to specific proteins on various cell types and can identify cell development stages through flow cytometry, histochemical applications and lectin microarrays. Lectins can indicate pathological conditions by identifying altered surface glycoproteins and glycolipids. Lectin has a multivalent binding site for the sugar moiety. Lectins are associated with varied taxa of microbes, plants and animals. Marine lectins are structurally diverse and grouped according to structural similarity of carbohydrate recognition domain (CRD) into Fucolectin type lectin, C-type lectins (CTLs), rhamnose binding lectin (RBL) Lily type, Ricin type and Tectonin type lectins.
Lectin producing marine species are Aphrocallistes vastus, Axinella polypoides, Geodia cydoniu, Ptilota filicina, Tridacna maxima, Haliotis laevigata, Megabalanus rosa , Balanus rostratus, Tachypleus tridentatus, and Cucumaria echinate (Ogawa et al., 2011), Palmaria palmate, Solieria robusta, Gracilaria verrucosa, Cystoclonium purpureum, Bryothamnion seaforthii, B.triquetrum, solieria filiformis, Enantiocladia duperreyi, Amansis multifidi, Hypnea musciformis, and green algae of genus Codium, Ulva lactuca, Caulerpa cuperssoides, Entermorpha prolifera, Ulva pertusa, Bryopsis plumose, Bryopsis hypnoides and marine algal genus Ptilota(Teixeira et al., 2012).
Lectins have shown varied applications in the field of biomedical, drug delivery systems, diagnostic markers, anticancer drugs, and therapeutic activities. Cyanobacteria Nostoc ellipsosporum and red algaeGriffithsia sps were used to obtain Anti-HIV and HCV lectins. Marine lectins have great potential as antiviral drugs against the transmission of enveloped viruses by preventing viral entry into host cells. Marine lectin has also shown antiparasitic, immunoenhancing, immunomodulating, mitogenic, cardiogenesis, and vasorelaxant activities. In diagnostic application, lectin specificity can be utilized to differentiate between carcinoma and normal human lymphocytes and fibroblasts. Altered glycan on cells or tissues surface can be recognized using lectin-based methods such as biosensors and histochemistry. Lectin and glycan interaction in biosensors can be analyzed by signals (Dan et al., 2016).
1.4. Marine peptidoglycan : Chondritin sulfate and hyaluronic acid are heteropolysaccharides of class glycosaminoglycan.
1.4.1. Chondroitin Sulfate:
Chondroitin sulfate (CS) is a sulfated polymer of glucoronate and N-acetylglucosamine linked by β-(1→3) glycosidic linkage. CS are classified according to attachment of sulfate group on Carbon atom into CS-A, CS-C, CS-E, CS-D and Cs-B respectively. Marine CS has been isolated from marine vertebrates including Whale, squid, salmon, skate, shark, king crab, sea cucumber and marine invertebrates likeCnidaria, Mollusca and Polychaeta . Shark fins of varied species including Dasyatis akajei, Scyliorhinus torazame, Surus oxyrinchus, Prionace glauca , Dalatias licha ,Mitsukurina owatoni are used as commercial sources of CS (Abdallaha et al., 2020).
Marine CS has many advantages as it is non-immunogenic, biocompatible, non-toxic, anti-inflammatory, and helps in cellular communication. Marine CS has an application in nerve regeneration, anti-inflammatory, anti-metastatic activity, tissue engineering scaffolds, anticoagulant activity, and biosensors. In tissue engineering, it is applied for bone repair, cartilage, and cutaneous wounds. To control biodegradability CS can be mixed with other polymers to make scaffolds. CS also has pharmacological applications such as coating material for implants and hydrogel in controlled drug release (Benito-Arenas et al., 2019).
1.4.2. Hyaluronic acid (HA) :
Hyaluronic acid is a natural nonsulfated polysaccharide made up of α-1,4 D glucuronic acid and β-1,3-N-acetyl-D-glucosamine, linked by (1→3)bonds. It is part of intracellular matrix of cartilage, umbilical cord connective tissue, skeleton and vitreous humor of cartilaginous fishes and the cell wall of marine bacteria Streptococcus zooepidemicus (Murado et al., 2012).
The HA activity is dependent on its size (Liao et al., 2005). HA can hold water molecules and this property of HA gives a large range of physical, chemical and biological activity such as biocompatibility, angiogenic, viscoelasticity and immune-stimulation. HA is also having shock-absorbing activities and acts as a lubricant for joint movement. In the skin, HA scavenges free radicals generated by the UV rays from sunlight and prevents cells from oxidative stress. HA has an application in the diagnosis of rheumatoid arthritis, cancer, and live pathologies, cosmetic fields such as plastic surgery, anti-aging cosmetics, arthritis treatment intraocular surgery, and drug delivery (Srivastava et al., 2015; Vázquez et al., 2013). Though data are scarce on biosensors.