High-precision flexible fabrication of tissue engineering scaffolds using distinct polymers

Abstract

Three-dimensional porous structures using biodegradable materials with excellent biocompatibility are critically important for tissue engineering applications. We present a multi-nozzle-based versatile deposition approach to flexibly construct porous tissue engineering scaffolds using distinct polymeric biomaterials such as thermoplastic and photo-crosslinkable polymers. We first describe the development of the deposition system and fabrication of scaffolds from two types of biodegradable polymers using this system. The thermoplastic sample is semi-crystalline poly(ε-caprolactone) (PCL) that can be processed at a temperature higher than its melting point and solidifies at room temperature. The photo-crosslinkable one is polypropylene fumarate (PPF) that has to be dissolved in a reactive solvent as a resin for being cured into solid structures. Besides the direct fabrication of thermoplastic PCL scaffolds, we specifically develop a layer molding approach for the fabrication of crosslinkable polymers, which traditionally can only be fabricated by stereolithography. In this approach, a thermoplastic supporting material (paraffin wax) is first deposited to make a mold for each specific layer, and then PPF is deposited on demand to fill the mold and cured by the UV light. The supporting material can be removed to produce a porous scaffold of crosslinked PPF. Both PCL and crosslinked PPF scaffolds fabricated using the developed system have been characterized in terms of compressive mechanical properties, morphology, pore size and porosity. Mouse MC3T3-E1 pre-osteoblastic cell studies on the fabricated scaffolds have been performed to demonstrate their capability of supporting cell proliferation and ingrowth, aiming for bone tissue engineering applications.