Advances in Organic Synthesis: Volume 8

Atta-ur-Rahman

• Verlag: Bentham Science Publishers
• Jahr: 2018
• ISBN:
  9781681085647
• Thema: Physical Sciences
• Thema: Organic Chemistry

Advances in Organic Synthesis is a book series devoted to the latest advances in synthetic approaches towards challenging structures. It presents comprehensive articles written by eminent authorities on different synthetic approaches to selected target mo

Chitosan and its Derivatives: Synthesis Strategy and Applications

Tecia V. Carvalho¹, Raphaela V. Barreto², Alysson L. Angelim³, Samantha Pinheiro Costa³, Walderly M. Bezerra⁴, Francisco E. A. Melo⁵, Afrânio A. Craveiro¹, Gloria Maria Marinho da Silva Sampaio⁶, Gilberto Dantas Saraiva⁷, Vicente de Oliveira Sousa Neto⁸, Vania M.M. Melo⁴, Ronaldo Ferreira do Nascimento^{9, *}

¹ Parque de Desenvolvimento Tecnológico, Av. Humberto Monte 2977, Campus do Pici, Universidade Federal do Ceará, PADETEC, CEP: 60440-593, Fortaleza, CE, Brazil

² Departamento de Ciências Animais, Universidade Federal Rural do Semi-Árido, Av. Francisco Mota, 572, Presidente Costa e Silva, CEP 59625900, Mossoró, RN, Brazil

³ Biotrends Soluções Biotecnológicas, Av. Humberto Monte 2977, Campus do Pici, Universidade Federal do Ceará, Galpão 16, CEP:60440-593, Fortaleza-CE, Brazil

⁴ Laboratório de Ecologia Microbiana e Biotecnologia, Departamento de Biologia, Universidade Federal do Ceará. CEP: 60455-760, Fortaleza, CE, Brazil

⁵ Departamento de Física, Universidade Federal do Ceará, CEP 60455-760, Fortaleza, CE, Brazil

⁶ Instituto Federal do Ceara - Mestrado em Tecnologia e Gestão Ambiental, CEP:60040-531, Fortaleza-CE, Brazil

⁷ Departamento de Física, Universidade Estadual do Ceará-UECE, CEP: 63900-000, Quixadá, CE, Brazil

⁸ Departamento de Química, Universidade Estadual do Ceará, CEP: 63900-000, Quixadá, CE, Brazil

⁹ Departamento de Química Analítica e Físico Química, Universidade Federal do Ceara- UFC, CEP: 60455-760, Fortaleza, CE, Brazil

Abstract

This chapter provides a recent description of chemical synthesis, encapsulation of chitosan microspheres and the incorporation of microorganisms involving technological advances to bioremediation of inorganic and organic environmental pollutants as well as their antimicrobial activity. In addition, the potential of chitosan and their derivatives in the bioremediation of water polluted by oil spills, heavy metals, dyes, phenols and pesticides is explored.

Keywords: Antimicrobial Chitosan, Bacterial Consortium, Bioaugmentation, Bioremediation, Carboxymethyl Chitosans, Chitosan Beads, Chitosan- Metal composites, Grafted Chitosans, Pollutants, Synthesis of Chitosan Derivatives.

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^* Corresponding author Ronaldo Ferreira do Nascimento: Departamento de Química Analítica e Físico Química, Universidade Federal do Ceara- UFC, CEP: 60455-760, Fortaleza, CE, Brazil; Tel/Fax: [phone]; E-mail: [email protected]

INTRODUCTION

Source of Chitin and Chitosan in Nature

Chitin and chitosan are non-toxic, biodegradable and biocompatible polymers produced by renewable natural sources. After the cellulose, the chitin compound is the second most abundant polymer found in nature, being a structural polysaccharide found in different species like the cell walls in the fungi, the cuticle of insects, shells and the exoskeleton of crustaceans.

Chitin is obtained from the crustacean shells by a chemical process of demineralization and deproteinization. Chitin contains acetyl groups (NHCOCH₃), which is deacetylated with concentrated NaOH solution to produce chitosan.

The chitosan is produced naturally and by chemical or physical hydrolysis with pendant acetyl groups on the polymer chitin chain. Chitin and chitosan consist of 2-acetamido-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-D-glucopyranose units attached by bonds Glycosidic β. However, these polymers differ in the relative proportion of these units and solubility.

Chitosan Properties

Chitosan is a biopolymer of the polysaccharide type, generally obtained by the deacetylation (hydrolysis of the acetamide groups) of chitin from the exoskeletons of insects and crustaceans of great economic and environmental importance [1, 2]. In fact, the chitin deacetylation is rarely complete since chitosan is obtained when the extent of the reaction reaches about 60% (or more) [3].

The deacetylation degree (DD) of chitosan (percentage of amino groups present in the biopolymer), is responsible for defining not only its chemical identity but also determining its biological applications. The DD of chitosan usually varies from 70 to 95%, for a molecular weight of 10 to 103kDa, and depends on the chitin characteristics and on the chemical or biological methods used in the purification process [3, 4].

Regarding the solubility of the chitosan and its derivatives, it is important to mention that while the chitin is insoluble in most organic solvents, the deacetylated chitosan is readily soluble in the acid acetic, acid formic and acid lactic, as well as other dilute acid solutions at pH range of 2.0 to 6.0. The primary amines are positively charged under slightly acidic conditions, provide their solubility, unlike chitin, providing chitosan with bacteriostatic properties [5].

According to the literature, the higher DD of chitosan influence some of its chemical and biological properties, such as hydrophobicity, ability to undergo crosslinking by crosslinking agents, and solubility and viscosity [6, 7].

In addition, the chitosan has various biological properties, such as biocompatibility, non-toxic, biodegradable, adsorbable, bioactivity, antimicrobial activity (fungi, bacteria, viruses), antiacid, antiulcer, and antitumoral properties, blood anticoagulants, hypolipidemic activity, bioadhesiveness [8].

Synthesis of Chitosan Derivatives

According to the literature [9], the chitosan derivatives can be classified into four main classes of materials: modified polymers, cross-...