Bidirectional Electrical and Optoelectronic Interfaces in Healthy and Ischemic Ex Vivo Rat Hearts

Electrophysiological studies are pivotal in exploring interactions between materials and cardiac biointerfaces. Recent advancements have introduced various novel conductor and semiconductor materials for bidirectional interfaces with cardiac models, facilitating low-intensity pacing alongside high spatiotemporal and high signal-to-noise ratio (SNR) recordings. The ex vivo rodent heart model serves as an effective platform for validating the functionalities of new materials and devices, bridging in vitro findings to translational insights while minimizing ethical and administrative concerns. In this protocol, we detail the isolation and ex vivo perfusion of adult rat hearts using a Langendorff apparatus, establishing precise bidirectional stimulation and recording with high-performance semiconductors and conductors, including nanoporous silicon, nanoporous carbon, and flexible mesh-like microelectrode arrays. Additionally, we present a myocardial infarction model induced by ischemia-reperfusion (I/R) injury, assessed through multichannel recording and mapping as well as infarct staining, enabling cardiac disease-relevant studies and potential therapeutic explorations. This methodology offers valuable insights into materials-bio interface research and the development of next-generation cardiac bioelectronics.