TEMPLATED SYNTHESIS OF CHITOSAN NANOCAPSULES WITH CONTROLLABLE SHELL THICKNESS AND POROSITY Emma C. Goethals 1 , Vipul Bansal 1,* , and Suresh K. Bhargava 1,* 1 *Email: School of Applied Science, RMIT University, GPO Box 2476 Melbourne VIC 3001, Australia vipul.bansal@rmit.edu.au / suresh.bhargava@rmit.edu.au ABSTRACT This study demonstrates the successful production of monodispersed, homogeneous chitosan nanocapsules with tunable properties such as controlled size, thickness and porosity. Through the use of a solid core silica template with a tunable mesoporous shell (SC/MS), hollow nanocapsules with different sizes, wall thickness, and porosity levels have been synthesized. These chitosan nanocapsules have been characterized using transmission and scanning electron microscopy. A hydrophobic drug curcumin was used as a model drug that was infiltrated in chitosan nanocapsules. The drug-encapsulation efficiency as a function of capsule size, thickness and porosity has been demonstrated using UV-Vis absorbance spectroscopy. The study provides a detailed understanding on how a control over nanocapsule synthesis parameters can provide a facile approach for attaining a controlled drug-release profile. Keywords: Chitosan, nanocapsules, curcumin, drug delivery, silica INTRODUCTION Chitosan, a biocompatible and biodegradable polymer, is derived from the partial deacetylation of chitin, the main component found in the exoskeleton of sea crustaceans. Chitosan has broad applications in the medical field because of its low immunogenicity and toxicity, in addition to good mechanical properties (Zeng & Ruckenstein 1996). Furthermore, it can be broken down by lysosomes in the body to harmless N-acetyl glucosamine (Gan & Wang 2007) making it a highly desirable material in forming carriers for drug deliver. So far there have been published reports of producing self- assembled chitosan nanospheres by way of ionic interaction, thermal or chemical cross- linking, solvent evaporation, interfacial acylation and coating of preformed template particles (Mora-Huertas, Fessi & Elaissari; Sinha et al. 2004). These processes can also be combined with emulsion, spray drying and membrane droplet techniques. Although these particles represent very promising drug delivery platforms, all these method except those utilizing a template particle, produce solid core chitosan particles, thus restricting their capabilities as a drug delivery vehicle by reducing the drug loading capacity only to the particle surface. In contrast, the use of a template onto which a chitosan layer is deposited, followed by subsequent removal of the template particle can result in a chitosan nano- or micro-capsule with a hollow interior which can be loaded with a substantially increased drug volume capacity. Therefore, well-controlled synthesis of chitosan nanocapsules will provide an obvious advantage over solid chitosan nanospheres reported in literature for drug-delivery applications.