Detection of mitochondrial bioenergetics using a novel bimodal 3D microelectrode array (MEA)-based biosensor.

Developing new label-free paradigms for functional assays in biomedical research has the potential to catalyze efforts in drug discovery and improve the understanding of complex disorders. Mitochondria are an essential organelle in nearly every eukaryotic organism that perform vital functions such as adenosine triphosphate (ATP) production, redox signaling, reactive oxygen species (ROS) homeostasis and regulation of programmed cell death. These activities are regulated by electrophysiological processes that occur in the inner mitochondrial membrane (IMM) and outer mitochondrial membrane (OMM) in response to metabolic demands, making them an important physiological marker for bioenergetic studies. Mitochondria dysfunction is an early pathological biomarker of complex diseases, such as diabetes, neurodegeneration, myopathy, cancer, and cardiovascular disease. Built atop a novel microfabrication strategy for 3D Microelectrode Arrays (MEAs), we demonstrate a 3D mitochondria biosensor capable of bimodal sensing of mitochondrial electrophysiology from the OMM and IMM using electrochemical impedance spectroscopy (EIS) and electrophysiology recordings. Data obtained using EIS displays impedance magnitude and phase characterization of mitochondria isolated from NIH3T3 and induced pluripotent stem cells (iPSC) models, these measurements represent the major functional outputs of cellular respiration and electron transport chain (ETC) activity through the detection of conductive and capacitive properties of the IMM. Additionally, time-resolved electrophysiological recordings from an NIH3T3 derived mitochondrial pellet captured sub-millisecond voltage transients, establishing a complementary real-time electrophysiological profile of mitochondrial membrane activity that can be attributed voltage dependent anion channel (VDAC) gating or IMM potential dynamics.