Self-gelling electroactive hydrogels based on chitosan-aniline oligomers/agarose for neural tissue engineering with on-demand drug release

Designing biomimetic scaffolds is an intellectual challenge of the realm of regenerative medicine and tissue engineering. An electroactive substrate should meet multidisciplinary mimicking the mechanical, electrical, and electrochemical properties of neural tissues. Hydrogels have been known platforms to regulate neural interface modulus, but the lack of conductivity always hampered their applications; hence, developing conductive hydrogels with on-demand drug release has become a concern of tissue engineering. In this work, electroactive hydrogels based on chitosan-aniline oligomer and agarose with self-gelling properties were synthesized, and their electrical, thermal, and electrochemical properties were characterized by Fourier transform infrared (FTIR), cyclic voltammetry (CV), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA), and four probe method . The conductivity of the as-prepared aniline oligomer-based hydrogel was similar to 10(-4) S/cm; which fell within the range of conductivities appropriate for applications in tissue engineering. The aniline oligomer played a key role in controlling the hydrogel properties by regulating the glass transition temperature and thermal properties. In addition, the swelling and degradation rates were decreased because of the hydrophobic properties of the aniline oligomer. The swelling capacity of the pristine hydrogel was similar to 800%, while that of the conductive hydrogel decreased to similar to 300%. The conductivity of the hydrogel was regulated by modifying the macromolecular architecture through aniline oligomer incorporation thanks to its conductivity on-demand drug release was observed by electrical stimulation, in which a large amount of the drug was released by voltage application. Biocompatibility analysis of the designed hydrogel was indicative of the conductivity enhancement, as reflected in the growth and proliferation of cellular activity.