Novel Biomimetic, Bioactive, Electrically Active Conducting Polymer Electrodes
Development of highly biocompatible electrodes that facilitate integration at the electrode-tissue interface.
Currently our research is focused on interactions between central nervous system (CNS) cells and conducting polymers towards development of novel biomimetic, bioactive materials and adaptive microelectrodes that facilitate establishment of a fully integrated electrode-tissue interface.
Chronic implantation of microelectrodes and neural prosthetic devices in the CNS is associated with tissue injury and inflammation. This results in neuronal loss near electrodes and encapsulation of the device in a high impedance barrier of glia and immune cells, undermining the goal of maintaining long-term communication with neurons.
It is our hypothesis that both the biocompatibility and electrical signal transduction capacity of neural prosthetic devices and deep brain stimulators can be greatly enhanced by integration with the technology that we are developing. Our studies showing that PEDOT can be polymerized around living cells and tissues with little toxicity suggests that PEDOT networks can be grown within living tissue, for the purpose of extending electrodes to contact healthy neurons beyond the halo of dead cells and inflammatory tissue that encapsulates chronically implanted neural prosthetics.
Previous studies from our laboratory developed methods for depositing the conducting polymer poly(3,4-ethylene dioxythiophene) (PEDOT) directly onto the electrode sites of MEMS devices and for templating micrometer and nanometer scale PEDOT surface features.
Modifying electrode sites with PEDOT usually results in a decrease in electrical impedance of the electrode by 1-2 orders of magnitude.
We can tailor PEDOT coatings to have a variety of morphologies and surface topologies including: pores (100 nm – 10 um diameter), inter-connected 3D lattice, fibrillar/hairy (10-100 nm X 5-10 um), nodular/rough (nanometer scale), tubular (nanomter diamter X as long as mm length), and cytomimetic (cell shaped-holes, neurite-templated tunnels & tubes).
A variety of proteins, including Nerve Growth Factor, collagen, laminin, and poly(lysine) can be incorporated into the PEDOT matrix. Protein within the PEDOT is bioactive. It can be recognized by cells in contact with the PEDOT and can be passively or actively released from the polymer matrix.
The conductivity of PEDOT can be controlled by using various dopants.
Funding
NSF DMR-0084304 and NIH NINDS NO1-NS-1-2338.