Preface

Alginates are polysaccharides found in both the intercellular matrix of brown algae and extracellularly covering some species of bacteria. They are widely used by the food industry, giving foods texture properties such as thickening, adhesion, emulsification, gelling, or fullness.

Alginate was characterized in the late nineteenth century and is currently obtained from brown algae collected in coastal regions at sea. Alginate can constitute up to 40% of the dry mass of these algae. Due to its unique properties, for gelling and thickening solutions and acting as immobilization support, the material has become a product of commercial importance. Alginate is widely used in food, cosmetics, and medicines and also finds application in the textile and paper industries. It is currently being used in innovative medical and pharmaceutical applications. Due to its characteristics, it is used as a thickener, emulsion and foam stabilizer, encapsulating agent, gelling agent, film-forming agent, and synthetic fiber, among other possibilities. The alginate currently used is extracted from algae; however, its production by microorganisms allows controlled exploitation of its natural sources.

Alginate is a linear copolymer consisting of the acids α-L-guluronic and β-Dmannuronic with 1–4 bonds. The material varies widely in terms of its proportion between mannuronic (M) and guluronic (G) residues, as well as its sequential structure and degree of polymerization. Thus, the material may have alternating sequences of MG residues and blocks consisting of two or more M or G residues. In many applications for which the material is used it has the ability to form gels whose characteristics depend on the M/G ratio and number of cross-links between polymer chains. Gels are formed in the presence of divalent cations such as Ca++ or Mg++, and the presence of G residue sequences is required to exhibit this ability.

This book is divided into the following sections: Introductory section, Pharmaceutical and Medical Uses, and Technological Applications. The first chapter is entitled Introductory Chapter: Alginates—A General Looking. The second section consists of Chapters 2 through 6, respectively: Pharmacological Effects and Utility as a Food Additive of Calcium Alginate; Current Perspective and Advancements of Alginate-based Transplantation Technologies; The Use of Alginate Hydrogels for the Culture of Mesenchymal Stem Cells (MSCs): *In Vitro* and *In Vivo* Paradigms; Alginate-Based Hydrogels in Regenerative Medicine; and Role of Alginates Combined with Natural Extracts to Prevent the Gastric Acidrelated Damage. The third and last section consists of two chapters: Importance of Alginate Bio-Ink for 3D Bio-Printing in Tissue Engineering and Regenerative Medicine and Application of Artificial Intelligence in Modern Healthcare Systems.

**II**

**Section 3**

and Regenerative Medicine

*by Sudipto Datta, Ranjit Barua and Jonali Das*

*by Sudipto Datta, Ranjit Barua and Jonali Das*

Technological Applications **107**

**Chapter 7 109**

**Chapter 8 121**

Importance of Alginate Bioink for 3D Bioprinting in Tissue Engineering

Application of Artificial Intelligence in Modern Healthcare System

Acknowledgments: This work has the support of Fundação para a Ciência e Tecnologia, through the strategic project UID/MAR/04292/2019 granted to MARE.

**Leonel Pereira and João Cotas**

**1**

Section 1

Introduction

MARE—Marine and Environmental Sciences Centre, Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal

Section 1 Introduction

**3**

**Chapter 1**

**1. Introduction**

alginates in different seaweeds.

from algae biomass [3].

molecule.

**2. History**

General Overview

*Leonel Pereira and João Cotas*

Introductory Chapter: Alginates - A

Alginate is an anionic polymer that occurs naturally in brown algae (Phaeophyceae), normally present on the cell walls of these organisms.

containing sodium, calcium, strontium, magnesium, and barium ions [2].

stable structure unlike the alginate with monovalent cations.

Alginate is a structural element designated to be the seaweed's main skeletal compound likewise the cellulose function in terrestrial plants, with the gel located in the cell walls and intercellular matrix conferring the mechanical strength and flexibility necessary to withstand the force of the water in which the seaweed grows [1]. Moreover, this function is reflected in the compositional difference of

Alginate varies in composition of the algae from 20 to 60% dry matter, but on average brown algae species has 40% alginate. Alginate in brown algae occurs as gels

Alginate is not a compound exclusively of brown algae because there are bacteria that can also produce alginate, but currently all commercial alginate is extracted

The biotechnological applications of alginate are based on specific effects of the alginate molecule and its variations depending on the covalent bonds with cations, such as calcium, sodium, or magnesium, and this allows for a great number of applications in several variations of the structure and conformation of the alginate

Alginates are in vogue for specialized knowledge as a pharmaceutical or biomedical ingredient or as compound for advanced biotechnology, and these investigations are turning to a more detailed study of the properties and structure of alginate, leading to points of scientific innovation that, associated with empirical

knowledge, will benefit the traditional techniques of alginate exploitation.

Alginic acid was first discovered and patented (patent date: 12 January 1881) by the British chemical scientist E. C. C. Stanford, and he continued the work on its discovery, contributing to the elucidation of the chemical structure of alginic acid [3]. The Stanford patent explains how the alginate can be extracted by soaking

Industrial applications of alginate are linked to the gelation, viscosity, and stabilizer properties that alginate attributes to the solutions and products in which it is present. Normally the alginate is a matrix of alginic acid bound cations, such as calcium, sodium, or magnesium. These ions give greater stability to the alginic acid molecule, where the divalent cations give alginate a very rigid conformation and a
