Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Saturday Speaker Abstracts

Localized Modulation of Single Cardiomyocytes Using PEDOT:PSS Conducting Polymer Microwires Scott Thourson 1,2 , Christine K. Payne 1,3 . 1 Interdisciplinary Program in Bioengineering, Georgia Institute of Technology, Atlanta, GA, USA, 2 Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA, 3 School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA. Electrical modulation of single cells is needed to better understand and treat dysfunctional heart and brain cells. Current methods, such as patch clamping or microelectrode arrays, suffer from mechanical rigidity, complex fabrication methods, poor chronic stability, or spatial limitations. Conductive polymer wires have a small diameter (150 nm – 8 µm), high charge density (> 5 mC cm -2 ) and relatively low Young’s modulus (~ 1 GPa) that could enable long-term modulation of individual cells in a soft tissue environment. The present research used PEDOT:PSS microwires grown from gold electrodes to locally stimulate action potentials in single rat neonatal cardiomyocytes. These conductive polymer wires had an electrical conductivity of 33 ± 21 S cm - 1 , determined with two point probe resistance measurements. Analysis of electrical current transients determined a charge storage density up to 6 mC cm -2 for the microwires. Successful cardiomyocyte stimulation was dependent on wire length, diameter, voltage, and wire separation. Since the local electric field stimulation was nonuniform, COMSOL was used in conjunction with experimental results to model the electric flux generated by PEDOT:PSS microwires near the cell membrane. The minimum electric flux needed for successful stimulation was found to be 1.71 ± 0.26 mV mm. These findings are important in developing small, tunable wires that can locally stimulate individual cells using nonuniform electric fields. We expect that these polymer wires will be useful for chronic, single cell level stimulation within brain, heart, or muscle tissue.

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