A novel GelMA-OrnMA electrically conductive bioink for developing engineered neural tissues

Abstract

A conductive matrix not only supports cell growth but also provides the potential to stimulate the cells. However, electrically conductive matrices often require synthetic polymers, nanomaterials, and a large number of ionic species. While enhancing electrical conductivity, often properties like transparency, mechanical stiffness, and biocompatibility are compromised, which can subvert suitability for neural tissue engineering. Further, the byproducts of matrix degradation can have unforeseen influences. Therefore, electrically active matrices are required that provide a suitable combination of electrical conductivity, mechanical properties, and biocompatibility in combination with bioprinting capability. Here, a novel biomaterial is described which is optically transparent, electrically conductive and highly biocompatible. We covalently incorporated zwitterionic functional groups in gelatin methacryloyl (GelMA) to obtain a composite matrix. The zwitterionic moieties were derived from Ornithine by synthesizing ornithine methacryloyl (OrnMA). Systematically, we demonstrated the suitability of GelMA-OrnMA hydrogels in providing stiffness matching the native neural tissues, supporting proliferation of human astrocytes in 3D culture, and electrical conductivity in the range required for electrically active cell types like astrocytes. Owing to their electrical conductivity, these matrices also influenced the growth of astrocytes, manifesting as changes in their organization and morphology. These findings suggest that GelMA-OrnMA has immense potential for developing engineered neural tissues.