Electroactive and antioxidant injectable in-situ forming hydrogels with tunable properties by polyethylenimine and polyaniline for nerve tissue engineering

[Display omitted] •Electroconductive, antioxidant, and dual crosslinked hydrogel was developed.•Hydrogels were obtained based on Schiff’s base linkages and ionic interactions.•Hydrogels’ properties can be tuned by introduction of branched PEI.•The degree of aniline grafting effected on the final properties of the hydrogel.•Electrical Stimulation was applied to P19 cells as a tool to direct cell fate. The injectable in-situ forming electroconductive hydrogels with antioxidant activity are promising candidates for nerve tissue engineering. In this study, we synthesized and developed a gelatin-graft-polyaniline/periodate-oxidized alginate hydrogel through the introduction of branched polyethylenimine (PEI) to improve the rheological properties. Moreover, antioxidant property, electroconductivity and the effect of external electrical stimulus on the nerve cell behavior were investigated. The results showed that by increasing the polyaniline content, the antioxidant activity, pore sizes, and swelling ratio of the hydrogel were increased, while the crosslinking density and storage modulus were decreased. The introduction of PEI accelerated the gelation time, decreased swelling ratio and pore size, and increased the storage modulus and crosslinking density. Cell studies showed that all formulations had supported the viability of P19 embryonic carcinoma cells with the neuritis elongation in the presence of the external electrical-stimulus. Gene expression of the neuronal markers, including Nestin, Pax-6, and β-tubulin III, was increased in all hydrogels; In addition, electrical stimulation significantly elevated the expression of these markers in high polyaniline-content hydrogel compared to the polyaniline-free hydrogel. In conclusion, the results suggest that the prepared injectable electroconductive hydrogels can be a promising approach for neural tissue engineering.