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

Interdisciplinary Program in Bioengineering, Georgia Institute of Technology, Atlanta, GA,

USA,

Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta,

GA, USA,

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

-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

, 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.