Chitin and Chitosan Composites for Bone Tissue Regeneration

Abstract

In the present world, where there is increased obesity and poor physical activity, the occurrence of bone disorders has also been increased steeply. Therefore, a significant progress has been made in organ transplantation, surgical reconstruction, and the use of artificial prostheses to treat the loss or failure of an organ or bone tissue in the recent years. Bone contains considerable amounts of minerals and proteins. The major component of bone is hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂] (60–65%) and is one of the most stable forms of calcium phosphate and it occurs along with other materials including collagen, chondroitin sulfate, keratin sulfate, and lipids. To remedy bone defects, new natural and synthetic materials are needed, which will have very similar properties as that of natural bone. Bone tissue engineering is a relatively new and emerging field, which paves the way for bone repair or regeneration. Polymers can serve as a matrix to support cell growth by having various properties such as biocompatibility, biodegradability, porosity, charge, mechanical strength, and hydrophobicity. Considerable attention has been given to chitin and chitosan composite materials and their applications in the field of bone tissue engineering in the recent years, which are natural biopolymers. This chapter reviews the various composites of chitin and chitosan, which are proved to be potential materials for bone tissue regeneration.

Introduction

A very significant clinical problem, which we face nowadays, is bone injuries and defects, which are due to trauma, osteoporosis, and tumors. Most of the people find it difficult to be healed naturally and they have to undergo multiple surgeries for recovery. Therefore, bone tissue engineering has become a highly promising tool to tackle the most challenging bone-related clinical issues. Bone tissue engineering has emerged as a new area of regenerative medicine and biomaterials have an essential function concerning cell adhesion, spreading, proliferation, differentiation, and tissue formation in three dimensions.

Polymers can serve as a matrix to support cell growth by having various properties (e.g., biocompatibility, biodegradability, porosity, charge, mechanical strength, and hydrophobicity) and they can be easily modified and altered by changing the constituents of monomers in different ratios, controlling polymerization conditions, or introducing various functional groups to them (Lee & Yuk, 2007). Because of the biocompatible and biodegradable behaviors of natural polymers, much attention has been paid to the natural polymer-based composites than synthetic polymer composites for bone tissue engineering applications. The natural-based materials are biopolymers, which include polysaccharides (starch, alginate, chitin/chitosan, hyaluronic acid derivatives) or proteins (soy, collagen (Col), fibrin gels, silk) and a variety of biofibers, such as lignocelluloses (Rezwan, Chen, Blaker, & Boccaccini, 2006).