Biopolymer Polyelectrolyte Complex Nanocomposites for Bone Tissue Engineering

Recent studies have shown that its necessary for synthetic matrix to provide similar mechanical response as cell’s host environment in the body for desired tissue growth [1,2]. Osteoblast cells reside in the rigid matrix made of collagen fibers and hydroxyapatite crystals. Therefore for the growth of proper functional bone tissue, its utmost necessary that scaffolds provide mechanical response similar to bone matrix. Bone also serves as a mechanical support to the body. Thus scaffolds used for bone tissue engineering should also provide adequate mechanical support to prevent collapse of the neonatal tissue. The mechanical response of scaffolds decreases significantly as porosity increases. The porosity of scaffold around 90% has been considered optimal for tissue engineering. At such high porosity, the mechanical strength and elastic modulus decreases significantly. Various polymers both of synthetic and biological origin have been investigated as a material for scaffold [3]. Synthetic polymers are biodegradable, biocompatible, and can be easily formed into different shapes and sizes. However, hydrophobicity, lack of functional groups and release of acidic products on degradation are causes of concern. Biopolymers such as collagen, chitin, chitosan etc. promote cell adhesion, proliferation and differentiation, and evoke minimal foreign body reaction on implantation [4]. But, they have inadequate mechanical properties for bone regeneration and tend to loose structural integrity under wet and body fluid conditions. The quest for scaffold materials which, not only promote cell adhesion, proliferation and differentiation but also have adequate mechanical strength to support bone tissue growth is still on. In the current work, we discuss the synthesis and characterizations of nanocomposites based on biopolymers and hydroxyapatite. The biopolymers used are chitosan and polygalacturonic acid. These two biopolymers are biocompatible, biodegradable and electrostatically complementary to each other. We have also investigated the molecular mechanics involved in their mechanical behavior. Their in vitro response have been investigated by seeding human Osteoblast cells and studying their adhesion, proliferation and differentiation. Synthesis and characterizations of nanostructured fibers based on chitosan and polygalacturonic acid will also be discussed here.