ABSTRACT
Natural polymers are having advantages like biodegradability and biocompatibility, which make them favorable for most of the drug delivery system (Schmidt, 2009). Nanoparticle drug delivery system is used because of its high bioavailability, reduced dosage and toxicity, targeted delivery, and so on. Chitosan (CS) is one of the commonly used naturally obtained polymers with various therapeutic uses. Chitosan ((1→4)-2-amino-2-deoxy-β-D-glucan), a linear polyamine with a high ratio of glucosamine to acetyl-glucosamine units, is a natural mucoadhesive cationic polymer, which is obtained by partial deacetylation of chitin (Banerjee et al., 2002). Chitosan (pKa = 6.5) is solubilized in acidic medium (Chen, 2003). The primary amino groups lead to special properties that render chitosan very interesting for pharmaceutical applications like development of controlled release drug delivery systems like chitosan gels, tablets, capsules, microspheres, microcapsules, and nanoparticles for parenteral, nasal, ophthalmic, transdermal, and implantable delivery of drugs, proteins, peptides, and gene materials (Chen et al., 2007). The free amino functional group in chitosan makes it possible to form nanoparticles by cross-linking, emulsion cross-linking, spray drying, desolvation with cationic salts, ionic complexation/coacervation or ionic gelation method by interacting with various other reactive groups such as alginates, dextran sulphate, sodium tri poly phosphate (STPP), polyethylene glycol (PEG), different ligands, antibodies, DNA and pH sensitive moieties, and so on. (Kumar, 2000) Chitosan can enhance the transmucosal absorption by increasing the paracellular permeability of intestinal epithelia. Chitosan nanoparticles are having good potential for the ocular drug delivery system because of its mucoadhesive nature (Campos, 2001). It has been extensively used in nasal drug and vaccine delivery (Csaba, 2008). Main advantage of chitosan nanoparticle is it can be used for hydrophilic drug entrapment. The hydrophilic nanoparticle remains in circulation for long time without PEGlyation, by avoiding reticulo endothelial system (RES). The other advantage of using chitosan nanoparticles is that they do not require any organic solvent or any other extreme conditions mainly in ionotropic gelation or complex coacervation technique which results in more stabilization of proteins and peptides.
