Impedance Modeling Providing Enhanced Understanding of Mitochondrial Bioenergetics Utilizing a Novel 3D Microelectrode Array-Based Biosensor

This study introduces for the first time a novel impedimetric biosensor [1], and modeling of mitochondrial activity from induced pluripotent stem cells (iPSCs) cultured in vitro. Assessment of mitochondrial energetic function was carried out through impedance analysis up to 10 MHz, and models were generated with special attention to the diffusion regime response. A 3D microelectrode array (MEA) coated/patterned with Ti/ Au served as interfacing platform to collect electrical signatures of isolated mitochondria pellets at low levels of background noise <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(&lt; 10\mu \mathrm{V})$</tex>. Mitochondria activity was imaged with fluorescence microscopy using Tetramethylrhodamine (TMRM). Surface roughness on the MEA was also calculated to evaluate the role of its active area. Electron transport chain control (ETC: 1, 5, 10 mM) [1], pelleted mitochondria (MT: Base, 1, 5, 10 mM), sucrose as a negative control (NS) and respiration buffer (RB) solutions were characterized and modeled through a modified Randles equivalent electrical circuit (EEC). Adaptation of Constant Phase Element (CPE) as the diffusion element in the Randles cell provided data fitting with error below 10% for all cases. CPE adjusted model was compared to the traditional Warburg-based model and showcased a better mapping to the experimental data.