Development of a new electroconductive nanofibrous cardiac patch based on polyurethane-reduced graphene oxide nanocomposite scaffolds

The progress of regenerative medicine strategies for myocardial infarction will be possible with the development of biocompatible biomaterials, which not only mechanically support infarcted myocardium zone but also have the proper electrical conductivity to transfer electrical pulses. In this study, novel electroconductive nanofibrous structures based on polyurethane/reduced graphene oxide (PU/RGO) were constructed. Polyurethane solutions in two (dimethylformamide:chloroform) and three (dimethylformamide:chloroform:tetrahydrofuran) solvent systems were electrospun that resulted in different fiber diameter. Tetrahydrofuran addition decreased the PU fiber diameter about halved. Then RGO was electrosprayed as a conductive constituent simultaneously with the electrospinning of PU. PU/RGO scaffolds containing 5, 10, 15 and 20 wt percent of RGO nanosheets were fabricated by adjusting the electrospraying injection rate. Scaffolds were comparatively characterized for surface morphology, crystal structure, conductivity, wettability, chemical functional groups, mechanical properties and RGO release. Scanning electron microscope images showed strong interaction of RGO with electrospun PU. The electrical conductivity of PU/RGO meets the percolation threshold at a 15% of electrosprayed RGO (3.46 × 10−5 S/cm), converting insulating PU into a conductive nanocomposite and it achieves its maximum value for PU/RGO20 (6.05 × 10−5 S/cm). Tensile testing analysis revealed enhanced Young's modulus and the ultimate tensile strength for PU/RGO scaffolds. The biocompatibility of scaffolds was confirmed with determining the metabolic activities of exposed endothelial and myoblast cells. PU/RGO scaffolds even at high amount of RGO not only did not show cell toxicity but also enhance the cell proliferation. These findings suggest that, the PU/RGO nanofibrous scaffold can be considered as a new electroconductive cardiac patch to support myocardial regeneration.