Integration of microelectrodes and highly-aligned cardiac constructs for in situ electrophysiological recording

Recapitulating the highly-aligned morphology and electrophysiological activity of native myocardium is essential for engineering functional cardiac constructs. Although recent advances have demonstrated the feasibility of using bioelectronics to record the electrophysiological activity of cardiac constructs, it is still a challenge to realize highly-aligned cellular organizations in electronics-embedded cardiac constructs. Here we propose a strategy to integrate platinum (Pt) microelectrodes into cell-laden fibrin hydrogel for the fabrication of highly-aligned cardiac constructs and support electrophysiological recording. The close contact between Pt microelectrodes and cardiomyocytes was demonstrated, and cardiomyocytes in the living constructs exhibited highly-aligned morphology. Accordingly, in situ electrophysiological recording was performed by local field potentials (LFPs) with amplitude between 10 and 155 μV over 50-h culture. The conduction velocities of LFPs were measured, in the range of 22.09 ± 2.02 to 26.34 ± 1.93 cm/s. In addition, we demonstrate that the embedded Pt microelectrodes can register the changes in electrophysiological signals of cardiac constructs in response to drugs and alter cardiac contractile behaviors with electrical stimulation.