Rapid Prototyping of Chitosan-Coated Alginate Scaffolds Through the Use of a 3D Fiber Deposition Technique

Three dimensional, periodic scaffolds of chitosan-coated alginate are fabricated in a layer-by-layer fashion by rapid prototyping. A novel dispensing system based on two coaxial needles deliver simultaneously an alginate and calcium chloride solutions permitting the direct deposition of alginate fibers according to any designed pattern. Coating of the alginate fiber with chitosan and subsequent cross-linking with EDC and genipin assured the endurance of the scaffold in culture environment for a prolonged period of time. The cross-linking protocol adopted, imparted to the scaffold a hierarchical chemical structure as evidenced by Confocal Laser Microscopy and FTIR spectroscopy. The core of the fibers making up the scaffold is represented by alginate chains cross-linked by ester bonds only, the periphery of the fiber are constituted by an inter-polyelectrolyte complex of alginate and chitosan cross-linked in all pair combinations. Fibers belonging to adjacent layers are glued together by the chitosan coating. Mechanical behavior of the scaffolds characterized by different layouts of deposition was determined revealing anisotropic properties. The biocompatibility and capability of the scaffolds to sustain hepatocytes (HepaRG) cultures was demonstrated. Typical hepatic function such as albumin and urea secretion and induction of CYP3A4 enzyme activity following drug administration were excellent, thus proving the potentials of these constructs in monitoring liver specific function.