Paper BI-TuM6
Development of a Novel Biodegradable and Cyto-Compatible Polyurethane for Use as a Bioink in Ink-Jet Printing

Tuesday, October 21, 2008, 9:40 am, Room 202

Biodegradable polyurethanes (PUs) were synthesized from methylene di-p-phenyldiisocyanate (MDI), polycaprolactone diol (PCL-diol) and N, N-bis (2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES), serving as a hard segment, soft segment and chain extender respectively. We evaluated the effects of this chain extender on the polyurethanes’ degradation rate, mechanical properties, hydrophilicity, antithrombogenecity, and ability to support fibroblast cell attachment and growth. The properties were evaluated by comparing these polymers with those having a 2,2-(methylimino)diethanol (MIDE) chain extender. Mechanical testing demonstrated that the PUs containing BES have tensile strengths of about 17 MPa and elongations up to 400%, higher strength and elongation than PUs containing MIDE. In vitro degradation assays showed the presence of sulfonic acid group decrease the degradation rate of the PU containing BES than that of the PU containing MIDE. Cytocompatibility studies showed that all the PUs are nontoxic, and support cell attachment and proliferation. In vitro platelet adhesion assay showed lower platelet attachment on PU containing BES than that on either PU containing MIDE. Additionally, due to the existence of sulfonic acid groups, the BES extended PU became water-soluble in basic condition and insoluble in acidic condition, a phenomenon that is reversible at pH value of 8.7, making this a pH sensitive polymer attractive for bioprinting applications. By adding acetic acid into an inkjet cartridge and printing it onto basic PU solution, precision fabricated scaffolds were obtained. We will show that these PU scaffolds have preprogrammed pores with fixed sizes of approximately 20 microns. After 5 days cell culture, fibroblasts are seen to attach and proliferate on the porous printed scaffolds, and a number of the cells penetrated into the pores. These results suggest that these PUs are promising candidates as synthetic inks used for customizable fabrication of tissue engineering scaffolds.