Cardiotoxicity drug screening based on whole-panel intracellular recording

Unintended binding of small-molecule drugs to ion channels affects electrophysiological properties of car- diomyocytes and potentially leads to arrhythmia and heart failure. The waveforms of intracellular action po- tentials reflect the coordinated activities of cardiac ion channels and serve as a reliable means for assessing drug toxicity, but the implementation is limited by the low throughput of patch clamp for intracellular recording measurements. In the last decade, several new technologies are being developed to address this challenge. We recently developed the nanocrown electrode array (NcEA) technology that allows robust, parallel, and long- duration recording of intracellular action potentials (iAPs). Here, we demonstrate that NcEAs allow compari- son of iAP waveforms before and after drug treatment from the same cell. This self-referencing comparison not only shows distinct drug effects of sodium, potassium, and calcium blockers, but also reveals subtle differences among three subclasses of sodium channel blockers with sub-millisecond accuracy. Furthermore, self-referencing comparison unveils heterogeneous drug responses among different cells. In our study, whole-panel simultaneous intracellular recording can be reliably achieved with ~94% success rate. The average duration of intracellular recording is ~30 min and some last longer than 2 h. With its high reliability, long recording duration, and easy- to-use nature, NcEA would be useful for iAP-based preclinical drug screening.