Mechanically and Electrically Enhanced Polyurethane-poly(3,4-ethylenedioxythiophene) Conductive Foams with Aligned Pore Structures Promote MC3T3-E1 Cell Growth and Proliferation

Abstract

Polyurethanes are of great interest in tissue engineering because of their tunable mechanical and nontoxic properties. Various fabrication techniques have been adapted to design polyurethane scaffolds that meet the needs of specific purposes. In this study, 3D flexible conductive polyurethane foam (PUF) was fabricated using a sequential procedure utilizing gas foaming and vapor phase polymerization methods. The conductive PUF produced shows an internal pore architecture allowing nutrients to be circulated. Its mechanical properties and interconnected pore shapes can also be tailored by either changing the mixing ratio of polytetramethylene ether glycol and polymeric methylene diphenyl diisocyanate or compressive pressure. In addition, the introduction of poly(3,4-ethylenedioxythiophene) (PEDOT) to impart electrical properties to the PUF results in long-term reliability in electrical and mechanical properties. In order to make aligned pore structures in the PUF, compressive pressures were applied during fabrication. Bending tests and resistance variation measurements of PUF-PEDOT and PUF-P (pressed)-PEDOT were conducted and compared. PUF-P-PEDOT demonstrated lower electrical resistance than PUF-PEDOT. Moreover, no significant variation in resistance occurred even after 5000 repeated bending experiments, meaning that PUF-P-PEDOT is sufficiently stable for flexible strain sensor applications. A water-soluble tetrazolium salt assay for the evaluation of biocompatibility was also conducted by using MC3T3-E1 cell culture. Aligned and conductive PUF structures exhibit enhanced cell growth and proliferation at day 7.