2008 NSTI Nanotechnology Conference and Trade Show - Nanotech 2008 - 11th Annual

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TechConnect Summit
Clean Technology 2008

Nanostructured Hybrid Organic Biomaterials for Neural Interfaces

M.R. Abidian, D.C. Martin, D.R. Kipke
University of Michigan, US

neural microelectrode, nanotubes, nanofibers, controoled drug release, hydrogel, neural interfaces

A low impedance electrode-tissue interface is important for maintaining signal quality for recording as well as effective charge transfer for stimulation. However, neural microelectrodes often have high impedance because of their small surface combined with encapsulation from reactive cellular response. Here we propose that nanostructured electroactive and biocompatible polymer coatings can stabilize the interface between microelectrodes and living tissue at the site of implantation for long term performance of neural prostheses. We hypothesize that the successful stabilization will occur: 1) when there is a smooth gradient of mechanical properties between the stiff electrode and soft tissue, 2) anti-inflammatory drugs are controllably delivered at the site of implantation to prevent scar tissue formation around the neural electrode, 3) the transport of charge carriers between device and neuron at the site of implantation is improved Hydrogel coatings on the neural probes should provide a mechanical buffer layer between the hard silicon-based probe and the soft brain tissue, a scaffold for growing of conducting polymer within the hydrogel matrix, and a diffusible barrier for controlling drug release. In order to enhance the electrical properties of the electrode sites, PEDOT was electrochemically polymerized on the electrode sites, around the nanofibers and eventually and inside the alginate hydrogel matrix. We have successfully established a method for fabrication of multi functional coatings for neural microelectrode arrays using electrospinning of anti-inflammatory drug- incorporated biodegradable nanofibers, encapsulation of these nanofibers by alginate hydrogel layer and eventually electrochemical polymerization of conducting polymers on the electrode site and growing within alginate hydrogel matrix. The surface morphology and degradation rate of PLDL75G25A has been studied and release profile of dexamethasone from PLLA, PLDLA and PLDL75G25A has been investigated. It has been demonstrated that alginate hydrogel coating could not only decrease the burst effect of dexamethasone release for controlling the long-term release patterns but also create a scaffold matrix for growing PEDOT within the alginate in order to increase the conductivity of electrode sites. We believe this method provides a generally useful means for creating low impedance controlled bioactive molecules coating for the neural prostheses and biosensors applications.

Nanotech 2008 Conference Program Abstract