Nanostructured biodegradable polymer networks using lyotropic liquid crystalline templates.

The physical properties, porosity, and physiological behavior of synthetic biodegradable hydrogels have been identified as highly critical design parameters in most tissue engineering materials applications. Nanotechnology may provide the means to manipulate these parameters by accessing control over the network structure of the biomaterial, providing unique property relationships that often result from nanostructured materials. In this study, a lyotropic liquid crystal (LLC) was used as a polymerization template in the formation of a photopolymerizable biodegradable PLA-b-PEG-b-PLA (PEG = poly(ethylene glycol); PLA = poly(lactic acid)) material with nanoscale lamellar morphology. Through ordering of the biodegradable monomer within the liquid crystal assembly, a 2-fold increase in maximum polymerization rate and a 30% increase in double bond conversion were realized over isotropic monomer formulations. The resulting network structure of the templated PLA-b-PEG-b-PLA material has a dramatic affect on the physical properties of the hydrogel including an 80% increase in network swelling and an approximately 230% increase in diffusivity. This increase in permeability and solvent uptake leads to rapid degradation of the lamellar templated samples, further demonstrating the influence of the LLC directed network structure on the porosity and physical properties of the biodegradable material. The ability to control the porosity, physical properties, and behavior of a biodegradable hydrogel simply by imparting LLC network structure, without changing the chemistry or biocompatibility of the polymer, could prove highly advantageous in the design of synthetic biomaterials for potential medical applications.