Electroactive hydrogels can be used to influence cell response and maturation
by electrical stimulation. However, hydrogel formulations which are 3D
printable, electroactive, cytocompatible, and allow cell adhesion, remain a
challenge in the design of such stimuli-responsive biomaterials for tissue
engineering. Here, a combination of pyrrole with a high gelatin-content
oxidized alginate-gelatin (ADA-GEL) hydrogel is reported, offering
3D-printability of hydrogel precursors to prepare cytocompatible and
electrically conductive hydrogel scaffolds. By oxidation of pyrrole,
electroactive polypyrrole:polystyrenesulfonate (PPy:PSS) is synthesized inside
the ADA-GEL matrix. The hydrogels are assessed regarding their
electrical/mechanical properties, 3D-printability, and cytocompatibility. It is
possible to prepare open-porous scaffolds via bioplotting which are
electrically conductive and have a higher cell seeding efficiency in scaffold
depth in comparison to flat 2D hydrogels, which is confirmed via multiphoton
fluorescence microscopy. The formation of an interpenetrating polypyrrole
matrix in the hydrogel matrix increases the conductivity and stiffness of the
hydrogels, maintaining the capacity of the gels to promote cell adhesion and
proliferation. The results demonstrate that a 3D-printable ADA-GEL can be
rendered conductive (ADA-GEL-PPy:PSS), and that such hydrogel
formulations have promise for cell therapies, in vitro cell culture, and
electrical-stimulation assisted tissue engineering.