Figure 1.

Schematic illustration of the formation of ADA‐GEL‐PPy:PSS conductive hydrogel. A) ADA‐GEL hydrogel precursor containing different molarities of Py and polystyrenesulfonate (PSS) is prepared. B) After 3D‐printing, the formation of polypyrrole (PPy) is triggered by oxidation of Py by immersion in FeCl₃ solution. C) Final ADA‐GEL‐PPy:PSS scaffolds are dually crosslinked using Ca²⁺ and microbial transglutaminase to respectively crosslink the oxidized alginate and gelatin network inside the hydrogel. D) Light microscopy image of 3D‐printed ADA‐GEL‐PPy:PSS in a grit‐like structure. Scale bar: 400 µm. E) Fourier infrared spectroscopy spectra of ADA‐GEL and ADA‐GEL‐PPy:PSS, with characteristic band vibrations at approximately 1540 and 1460 cm⁻¹ indicating symmetric and asymmetric stretching characteristic for Py, verifying the presence of PPy inside ADA‐GEL. F) Scanning electron microscopy (SEM) image of an ADA‐GEL‐PPy:PSS hydrogel cylinder indicating the formation of a dense globular PPy structure on the ADA‐GEL hydrogel surface in comparison to untreated ADA‐GEL (Figure S1, Supporting Information). Scale bar: 400 nm.