In situ pPy-modification of chitosan porous membrane from mussel shell as a cardiac patch to repair myocardial infarction

• A pristine scaffold was developed via in situ pPy modification on mussel shell. • The subtle 3D structure was more vital for cell maturation than mussel-inspired PDA. • The shell-pPy derived cardiac patch presented synchronous contraction. • Shell-pPy could induce vascularization without any additional proangiogenic factors. Polypyrrole (pPy), a widely-used conductive material, can create an electrophysiological condition for the exogenous cardiomyocytes (CMs) via its conductivity, biocompatibility and available processing method. Our previously developed flexible scaffold from the mussel-derived chitosan shell possessed multiscale, interconnected-porous structure and proper stiffness, which was a promising tissue substitute for wound healing. Here, a 3D pristine hybrid scaffold was fabricated by incorporating polypyrrole into the mussel shell-derived membrane (shell-pPy). The pyrrole monomers were grafted onto to the shell membrane and then in situ polymerized to form conjugated pPy-chitosan shell using FeCl 3 . The developed pPy-chitosan shell was used to produce an engineered cardiac patch (ECP). The shell-pPy ECP maintained subtle spatial structure and was granted well cellular viability, aligned morphology, abundant striation and organized CX43, robust contraction and rapid calcium transients in vitro . When transplanted into the infarcted hearts, the developed shell-pPy ECP could also mimic the mechano-electronic function for cardiomyocytes maturation and integrity. Notably, obvious angiogenesis was triggered, and cardiac pumping performance was promoted in the infarcted area by the shell-pPy ECP. The study highlighted a functional pPy-modified cardiac patch with suitable conductivity, subtle 3D structure, and mechanical property can serve as an ideal ECP to mimic cardiac niche for myocardial repair.