The morphology, mechanical properties and ageing behavior of porous injection molded starch-based blends for tissue engineering scaffolding

Abstract

One important parameter in the tissue engineering of hard tissues is the scaffold. A scaffold is a support in which cells are seeded and that should create the adequate environment for the cells to attach and proliferate. Furthermore the scaffold should allow the flow of an appropriate culture media, providing nutrients to the cells and simultaneously removing the metabolites resulting from the cells activity. One of the possibilities is to obtain solid foamed structures that will enable the cells to attach, spread into the inner surfaces and start to produce extracellular matrix. Ideally, if the scaffold is produced from a biodegradable material, it should degrade at a pace that is in phase with the formation of the new tissue. In this work it was studied the production of porous structures from biodegradable polymers for use as scaffolds for bone tissue engineering. Two materials were studied, starch compounded with poly(ethylene-vinyl-alcohol) (SEVA-C) and starch with poly(lactic acid) (SPLA). The porous structures were obtained by injection molding with a blowing agent to control the porosity, interconnectivity and degradation rate. In previous attempts, the current starch compounds proved to be very difficult to process by this method. This study includes the characterization of the mechanical properties, water absorption and of the degradation kinetics of the 3-D porous structures. Two starch-based biodegradable 3D porous structures were successfully processed in conventional injection molding and the foaming was obtained by means of the use of a blowing agent. The mechanical properties are very promising as well as the improved degradation kinetics when compared with the synthetic polymers alone, although the degree of porosity and of interconnectivity needs to be improved in further work.