(695h) Nanostructured Photo Cross-Linked Biopolymers in Wound-Healing and Drug Delivery Applications

Chitosan materials have attracted significant attention in the past decade due to their inherent antimicrobial and haemostatic properties, biocompatibility, and renewable nature. Wound dressings containing these cationic polysaccharide fibers have been shown to promote wound healing and prevent infection while also slowing blood loss^{1, 2}.  In addition to the already-promising potential of chitosan, further improvement can be accessed by more closely mimicking the structure of the extra cellular matrix. Increased cell survival and attachment have been demonstrated on nanostructured synthetic polymers relative to their isotropic counterparts³. The overall goal of this work is to determine if sub-micron order, as caused by surfactant templating of the solution prior to cross-linking, can improve the transport properties and wound-healing capabilities of cross-linked chitosan materials. Low-molecular weight chitosan was functionalized with photopolymerizable groups via Michael-addition of 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AOHPMA)⁴. Various surfactants were added to induce nanostructure in the solution and subsequent hydrogel polymers. Nanostructure was characterized using small-angle x-ray scattering and polarized light microscopy. The transport properties of the hydrogels, including water uptake and drug release rates, were measured gravimetrically and spectroscopically, respectively. Although only small indications of nanostructure presence were observed, very significant differences in transport properties resulted from the use of varying types and concentrations of surfactant. The results thus indicate that the sub-micron order of these chitosan materials can be manipulated and tailored to specific applications using surfactant templating. The cytotoxicity of the templated hydrogels and non-cross-linked solutions was evaluated using a colorimetric cell viability assay with human fibroblast cells. The cytotoxicity results further enforced the potential of the material as biocompatible. Future studies will investigate the mechanical properties of chitosan hydrogels as well as their effect on the wound-healing process in vivo. Better control of polymer nanostructure and further understanding of its role in cell-material interactions are crucial to the advancement of chitosan biomaterials for use in many applications, including wound-healing, drug delivery, and tissue scaffolding applications.

References:

(1) Muzzarelli, R. A. A. Chitins and chitosans for the repair of wounded skin, nerve, cartilage and bone. Carbohydr. Polym. 2009, 76, 167-182.

(2) Jayakumar, R.; Prabaharan, M.; Sudheesh Kumar, P. T.; Nair, S. V.; Tamura, H. Biomaterials based on chitin and chitosan in wound dressing applications. Biotechnol. Adv. 2011, 29, 322-337.

(3) Clapper, J. D.; Pearce, M. E.; Guymon, C. A.; Salem, A. K. Biotinylated biodegradable nanotemplated hydrogel networks for cell interactive applications. Biomacromolecules 2008, 9, 1188-1194.

(4) Jiang, M.; Wang, K.; Kennedy, J. F.; Nie, J.; Yu, Q.; Ma, G. Preparation and characterization of water-soluble chitosan derivative by Michael addition reaction. Int. J. Biol. Macromol. 2010, 47, 696-699.