Nanocellulose/polypyrrole hydrogel scaffolds with mechanical strength and electrical activity matching native cardiac tissue for myocardial tissue engineering

Tissue engineering offers a promising alternative therapy for myocardial infarction, which is associated with high mortality rates. Meanwhile, excellent biocompatibility and conductivity are indispensable features of cardiac tissue engineering scaffolds that facilitate electrical signal transmission between cardiomyocytes. In this study, 2,2,6,6-tetramethylpiperidine-1-oxy (TEMPO) -oxidized cellulose nanofibers (TOCN) were crosslinked by iron ions, then polymerized with pyrrole monomer to obtain in situ polymerized polypyrrole nanocellulose composite hydrogel scaffolds for myocardial tissue engineering. The composite hydrogel exhibited mechanical properties (50 ~ 75 kPa) and electrical conductivity (5 × 10^–5 S·cm⁻¹ ~ 1 × 10^–3 S·cm⁻¹) that match those of natural myocardial tissue, while it was non-cytotoxic (relative growth rate > 90%) and biocompatibility. At the same time, cells cultured on the TOCN-PPy scaffold showed increased expression of myocardial specific proteins such as connexin 43 and cardiac troponin T. Thus, the TOCN-PPy composite hydrogel showed a broad application prospect in the field of myocardial tissue engineering scaffold.