Direct local polymerization of poly(3,4-ethylenedioxythiophene) in rat cortex

Area of Science:

• Biomaterials Science
• Neuroscience
• Polymer Chemistry

Background:

• Glial scar formation around implants hinders chronic brain-machine interface (BMI) function.
• Current strategies to mitigate glial scarring include surface modifications, drug delivery, and altered probe geometry.
• Establishing reliable, long-term neural communication across scar tissue remains a significant challenge.

Purpose of the Study:

• To investigate the in situ polymerization of conductive polymers, specifically poly(3,4-ethylenedioxythiophene) (PEDOT), within neural tissue.
• To demonstrate a novel method for delivering and polymerizing monomers directly at the target site for BMI applications.
• To assess the feasibility of overcoming glial scar encapsulation through localized polymer formation.

Main Methods:

• Delivery of the 3,4-ethylenedioxythiophene (EDOT) monomer into the rat cortex using a microcannula.
• Simultaneous electrochemical polymerization of the EDOT monomer using a microwire electrode inserted into the tissue.
• Optical microscopy was used to examine the morphology and extent of the resulting PEDOT polymer cloud.

Main Results:

• Successful in situ polymerization of PEDOT was achieved directly within the brain tissue.
• The polymer cloud extended significantly from the electrode tip, spanning distances greater than 1mm into the surrounding tissue.
• The morphology of the polymerized PEDOT within the neural environment was characterized.

Conclusions:

• Direct in situ polymerization of conductive polymers like PEDOT offers a promising strategy for establishing long-term BMI function.
• This method demonstrates potential for creating a conductive pathway that bridges or mitigates the effects of glial scar tissue.
• Localized polymerization of EDOT represents a novel approach to enhance neural interface reliability and longevity.