Spatially Resolved Photostimulation of Cardiac Activity Using Optoelectronic Peptides

Engineering physiologically relevant cardiac substrates requires precise control over both electrical and mechanical cues to guide cardiomyocyte functions and features. In this work, we report a biomolecular-based approach toward spatially controllable photostimulation of cardiac behavior via digital light processing of conductive interfaces on a range of substrate stiffnesses. The symmetric peptide-quaterthiophene-peptide units are designed to form conductive patterns atop biopolymeric hydrogels, allowing for microscale spatial control of photoconductive pathways that can influence cardiomyocyte alignment and intercellular communication in a light-activated manner. Substrate stiffness was modulated through adjusting material composition across a physiologically relevant range to reflect healthy and fibrotic cardiac tissue conditions. The ability to tailor the geometry of conductive pathways across a range of biomaterial interfaces and stiffnesses enables systematic assessment of how electrical signals from patterned optoelectronic peptides regulate cardiomyocyte behavior. Neonatal rat ventricular myocytes (NRVMs) cultured on π-conjugated peptide-based substrates exhibited enhanced alignment, synchronous contractility, and altered calcium flux dynamics compared to nonconductive substrates. Furthermore, the optoelectronic cardiac biomaterial-based scaffolds were shown to possess biological photostimulation capabilities, specifically enabling light-induced localized stimulation of excitable cells for high-resolution stimulation without the need for external electrodes or genetic modifications necessary for optogenetic approaches. Photostimulated NRVMs interfaced with optoelectronic peptide structures were shown to be more confined to the printed conductive patterns, with more cell localization and structural remodeling with respect to the patterns than in non-photostimulated conditions. The peptide-based platform presented here provides a potential approach to control mechanical and optoelectronic cues using microscale patterns in vitro, while opening avenues for advanced cardiac disease modeling, drug development, and the development of complex bioelectronic cardiac interfaces.