1.1.1. Alginate:
Alginates are components of the cell wall of seaweeds includingLaminaria, Macrocystis, Ascophyllum, Eclonia, Lessonia, Durvellia,
Sargassum as magnesium, calcium and sodium salts of alginate. These are
anionic, nontoxic, biocompatible, biodegradable, polysaccharides with
controlled porosity (Gomez et al., 2009). Algin is formed by
copolymerization of β-D- mannuronate and α-1-guluronate (1→4′)-linkage
and gelation is affected by pH. Alginates drawn out from various sources
have different lengths and varying compositions of monosaccharides.
Purified alginates may be applied to form different structures like
fibers, beads, hydrogels or films.
Alginate hydrogels are formed by various cross-linking associations of
anionic and multivalent inorganic cationic alginates. Hydrogels have a
structural resemblance to extracellular matrices of living tissues and
are widely studied as a scaffold. The mechanical toughness of hydrogels
helps in maintaining their structure in membranes, avoids breaking when
in use, and after tissue adherence. Drug delivery through alginate
hydrogels is pH sensitive and in acidic conditions, gel deters the drugs
tight and in neutral conditions, carboxylic group on alginate
deprotonates leading to network swelling and drug release (Silva et al.,
2008). Some limitations of alginate hydrogels are low porosity,
swelling, degradation, mechanical rigidity, cell attachment or
detachment of bio-active molecule by physical or chemical modification.
Alginate biomaterial has an application in the biomedical field (Rossi
et al.,2018), tissue regeneration, wound healing (Campiglio et al.,
2020), three dimensional (3D) printing (Wang et al., 2018), in
vitro modeling (Chu et al., 2018), and biosensing (Sun et al., 2020) .