New Jersey Center for Biomaterials

This project is being pursued in collaboration with NIBIB P41 Center for Neural Communication Technology (CNCT) at the University of Michigan and Wadsworth Center. Core S is fabricating devices that can be implanted into brain in order to stimulate and/or read brain neural signals. The neural probes that are now available are based on lithographic fabrication techniques. The probes are inserted into the brain using an insertion device, which is currently a metallic electrode coated with a dielectric material embedded in either a silicon or a polymeric (Parylene) shuttle - both non-biodegradable. The purpose of the shuttle is to provide the mechanical properties that enable insertion of the electrodes/probes, which then elict two distinct tissue responses: first, an acute response to the injury due to the insertion of the probe, and second, a chronic long term response to the foreign body present in the brain. These responses arise from non-neuronal cells, mostly microglia and astrocytes. This leads to a reduction, and sometime elimination, of the probe function due to isolation from the immediately surrounding neurons. The task for the Core S – CNCT collaboration is to provide a solution to this problem by designing a probe in which the shuttle material will be a biodegradable polymer from the Kohn lab polymer library. This polymer will be designed to meet the following required properties: mechanical rigidity for the probe insertion; ability to carry a drug (such as dexamethasone) that will diminish the acute and chronic tissue response (immunosuppressant); and a degradation rate that will eliminate the chronic tissue response to the foreign body simply by eroding out of the site, leaving an electrode which is small enough not to provoke additional immune responses.

Immunological response to the insertion of a 150 μm wide poly (DTEc) fiber. The fiber was inserted into the brain of a test animal (rat) without the help of a silicon probe indicating that the fiber is sufficiently stiff for this purpose. The immunological response to the polymer was indistinguishable from that of the silicon probe.