Novel Biohybrid Conducting Polymer-Hydrogel Electrodes
Neural prosthetic devices implanted in the brain and central nervous system (CNS) trigger inflammatory responses that result in neuronal loss and formation of a fibrous glial encapsulation of the device, inhibiting signal transduction and decreasing device stability. To achieve stable, long-term functional stimulation and recording of neurons via implanted neural electrodes, it is necessary to accommodate for the large differences in mechanical properties between the stiff device and the soft nervous system tissue. Biocompatibility and low electrical impedance at the interface are central to the ability of the device to function.
Recently we’ve developed methods for coating device electrode sites with a hybrid conducting polymer-bioactive hydrogel which provide a mechanical buffer between the hard electrode and the soft tissue, allowing for more efficient communication by increasing the effective interfacial surface area thus lowering the impedance of the electrode site. Conductive polymers offer the ability to deposit molecularly thin polymer electrode networks through hydrogel matrices. The resulting highly diffuse polymer network extends the electrodes’ surface closer to the viable neurons while the hydrogel scaffold limits protein adsorption to the electrode and creates a permissive environment for cell immobilization.
Hydrogels are widely used biomaterials that have many pharmaceutical and biomedical applications because their high water content and low interfacial tension with the surrounding biological environment makes them generally biocompatible.
The hydrogel-conductive polymer electrodes can be used to electrically
stimulate nerve cells immobilized in the matrix. In order to fully control the morphology of nerve cells contained within the hydrogel-conductive polymer electrodes, it is necessary to incorporate extracellular matrix components into hydrogel.
Funding
NSF DMR-0084304 and NIH NINDS NO1-NS-1-2338.