**2. Alginate properties**

*Laminaria hyperbola, Laminaria Digitata, Laminaria japonica, Ascophyllum nodosum, and Macrocystis pyrifera* are all well-known stains of brown algae obtained from seaweeds, which are responsible for making commercially available alginates [5, 6]. In general, alginates have water-insoluble properties; they are washed, crushed, dried, powdered, and treated with the basic compounds, especially NaOH or KOH, to make sodium/potassium salt of alginic acid, which is water soluble. Alginic acid, in other words, known as algin, occurs naturally in edible carbohydrates found in brown algae. It has hydrophilic nature and makes a viscous gum when hydrated [7]. With metals such as sodium and calcium, its salts are called alginates. Its color ranges from white to yellowish brown. Sodium alginate and alginic acid of sodium salt are the famous names of alginates in the market, and it is available with these two names. Alginic acid is a crucial component of the biofilms produced by *Pseudomonas aeruginosa* [8, 9]. Alginate's acidic behavior makes them an appropriate biodegradable biopolymeric product in biomedical and pharmaceutical applications. Because of their acid behavior, alginates make gels due to the presence of Guluronic acid (G) monomer in alginates within a less time period, especially the presence of Ca2+ ions [10]. This feature of gelling permitted Alginate to possess wide range applications, including encapsulation of various fragments or even cells interior of alginate matrix along with very less cons. The alginates have a carboxylic group for numerous applications and can be modified based on the application [11]. Exopolysaccharide forms of alginates are present within *Pseudomonas a*nd *Azotobacter* bacteria [11, 12]*.* These two bacterial classes are very potent alginate producers, can synthesize alginates with particular monomer formulations, and may be capable of producing 'tailor-made' bacterial alginates using recombinant DNA technology and engineering in protein.

*Introduction to Alginate: Biocompatible, Biodegradable, Antimicrobial Nature and Various… DOI: http://dx.doi.org/10.5772/intechopen.110650*

#### **2.1 Structure and characterization**

Alginates are a member of the unbranched biopolymer family. The alginates contain 1,4-ß-D-mannuronic acid (M) and 1,4 α-L- guluronic acid (G) monomers, with a homogenous (poly-G, Poly) or heterogenous (MG) block combination that is proven by partial acid hydrolysis [13]. Alginates are available in different locations of a sea bed and have different molecular weights ranging between fifty thousand and five lakhs. Different parts of seaweed contain different types and quantities of Alginate in their cell walls [14]. Alginates are provided a flexible, mechanical structure to the seaweeds and cushion them from possible inflammation when the seaweeds are subjected to strong water motion. Alginate viscosity is always PH responsive, and increment in viscosity is the principal signature of decrement in pH and reaches a pH ~3.5 because carboxylic groups in Guluronic acid is the part of the alginate structure protonated and make hydrogen bonds [15, 16]. Alginates may deal with different molecular weights depending upon the requirement to analyze the pregel viscosity of the solution or post-gelling distribution strength in a separate manner. The viscosity of the solution is maintained by a mixture of high and low-molecularweight alginate polymers [16].
