Bioelectronic Direct Current Stimulation at the Transition Between Reversible and Irreversible Charge Transfer

Area of Science:

• Bioelectronics
• Biocompatible materials
• Electrophysiology

Background:

• Endogenous electric fields (EFs) are crucial for biological processes like tissue regeneration and wound healing.
• Direct current stimulation (DCS) mimics EFs for therapeutic applications but faces challenges with toxic byproducts from electrode-tissue interactions.
• Poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes offer improved biocompatibility over traditional metal electrodes for DCS.

Purpose of the Study:

• To investigate if PEDOT electrodes can be engineered for reversible and biocompatible charge transfer during DCS.
• To understand the relationship between electrode capacitance and reactive oxygen species (ROS) generation.

Main Methods:

• Cyclic voltammetry and chronopotentiometry were used to study charge transfer dynamics.
• Direct measurements of hydrogen peroxide (H2O2) and oxygen (O2) quantified ROS generation.
• Various PEDOT formulations and back electrodes were analyzed.

Main Results:

• All tested electrode materials generated ROS during DCS.
• Increasing the capacitance of PEDOT electrodes delayed the onset of ROS generation.
• A correlation between electrode capacitance and ROS production was identified.

Conclusions:

• PEDOT-based electrodes can be optimized to enhance biocompatibility in DCS applications.
• Higher electrode capacitance is a key factor in mitigating ROS production during DCS.
• These findings support the development of advanced bioelectronic devices for prolonged, reversible DCS therapies.