From: Dr. Marc-Alexander Fluks Source: Analytica Chimica Acta Preprint Date: May 25, 2021 URL: https://www.sciencedirect.com/science/article/abs/pii/S0003267021005043 Broadband electrical impedance as a novel characterization of oxidative stress in single L6 skeletal muscle cells ------------------------------------------------------------- Caroline Ferguson(a), Niccolo Pini(b), Xiaotian Du(c), Marco Farina(d), James M.C.H wang(c), Tiziana Pietrangelo(b), Xuanhong Chenga(e,*) a Department of Bioengineering, Lehigh University, Bethlehem, PA, USA b Department of Neuroscience, Imaging, and Clinical Science, University G. D'Annuzio, Chieti-Pescara, Italy c Department of Electrical Engineering, Lehigh University, Bethlehem, PA, USA d Department of Engineering of Information, University Politecnica, Delle Marche, Marche, Italy e Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA, USA * Corresponding author. Department of Bioengineering, Lehigh University, Bethlehem, PA, USA. Email: email@example.com Received 4 May 2021 Revised 18 May 2021 Accepted 20 May 2021 Available online 25 May 2021. Abstract Oxidative stress (OS) is one of the leading causes of cytotoxicity and is linked to many human physio-pathological conditions. In particular, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) induced by OS is debilitating to quality of life, while no clear biological markers have been identified for diagnostic measures. Recently, impedance measurements of peripheral blood cells of ME/CFS patients have been shown as a promising approach to diagnose the disease. Inspired by this study and aiming to interrogate muscle cells directly, we investigated if broadband measurements of single muscle cells could differentiate normal and oxidatively stressed cell populations. We first optimized a protocol through H2O2 treatment to introduce oxidative stress to cultured rat L6 skeletal muscle cells. The treated cells were further characterized through broadband impedance spectroscopy of single cells using a microfluidic lab-on-a-chip system. The resulting dielectric properties of cytoplasm permittivity and conductivity are electrically distinct from normally cultured cells. The reflection and transmission coefficients, ΔS11 and ΔS21, of the normal cells are tightly clustered and closely resemble those of the cell-free solution across the frequency range of 9 kHz to 9 GHz. On the other hand, dielectric properties of the oxidized cells have a wide distribution in the GHz range, deviating both in the positive and negative directions from the normally cultured cells. Simulation results guide our hypothesis that the dielectric differences could be linked to ion alterations, while calcium imaging directly supports the contribution of calcium flux to the observed deviation of S parameters. The unique electrical profile associated with oxidized cells in the GHz frequencies provide a framework for future development of technologies to diagnose oxidative-stress related diseases such as ME/CFS. Keywords: Oxidative stress, broadband electrical sensing, dielectric, calcium signaling, microfluidic, single cell -------- (c) 2021 Elsevier B.V.