Doctor of Philosophy
School of Chemistry
Mat Amin, Khairul Anuar, Polyelectrolyte complex materials from chitosan and gellan gum, Doctor of Philosophy thesis, School of Chemistry, University of Wollongong, 2011. http://ro.uow.edu.au/theses/3452
The demand for wound management treatment especially advanced and active wound care products are huge. Polyelectrolyte complex (PEC) materials have been reported as a promising and novel way to develop wound dressings. The research presented in this thesis aimed to utilise the biopolymers chitosan (CH) and gellan gum (GG) in the preparation of PEC films. These films were prepared by dipping free-standing CH and GG films into oppositely charged solutions. Studies on PEC films showed that the mechanical characteristics depend on the solution and film pH, as well as the order of addition of the biopolymers. GG films immersed into CH solutions were found to consist of an inner GG layer and two outer CH layers, whereas in the reverse addition process, GG diffuses into the CH layer. The different in film composition was related to differences in pH and persistence length of GG and CH. Similar mechanical characteristics were observed for PEC coated wool fibres. The observation of the inability of CH solutions to diffuse into GG materials was used to develop dual layer films for future wound dressing applications. The upper layer was designed to act as a bacterial resistance layer, while the bottom layer was designed to promote cell viability and proliferation. Titanium dioxide (TiO2), silver and zinc oxide nanoparticles as well as the antibiotic levofloxacin (Lev) were incorporated into CH and GG films to assess their ability to improve the biopolymers’ antibacterial and cell viability properties. CH-Lev films displayed strong bacterial resistance against Escherichia coli, which was attributed to fast release (within 30 min) of levofloxacin. GGTiO2 composites exhibited the best cell viability and cell proliferation of all materials considered. Dual layer films consisting of a CH-Lev upper layer and GG-TiO2 composite as bottom layer were found to be mechanically robust and flexible. The water vapour transmission rates (WVTR) of dual layer films is comparable to WVTR values reported for commercial wound dressing such as Cutifilm, Tegaderm, Bioclusive, Duoderm and Intrasite. As conclusion, PEC materials from CH and GG designed with future wound dressing applications were successfully prepared.