Biomaterials Strategies Towards Multimodal Neural Probes for Chronic Neural Recording, Chemical Sensing and Delivery

Microelectrode array (MEA) devices, placed in the nervous system to record and modulate neuroactivity have demonstrated success in neuroscience research and neural prosthesis applications. Functionalizing the microelectrode sites on MEAs to enable neurochemical sensing and delivery adds additional dimensions of information, and presents tremendous potential for understanding neural circuits and treating neurological diseases. In this talk, I will introduce the methods by which we enable chemical sensing and delivery from MEAs. By incorporating nanocarbon into the conducting polymer electrode coating, we achieved direct detection of electroactive species such as dopamine, melatonin, and serotonin. By immobilizing enzymes or aptamers on nanostructured electrodes, we achieved multisite detection of glutamate, GABA, and cocaine. By incorporating nanocarriers into conducting polymer coating, we enabled on-demand drug delivery. Multisite and multiple analyte detection or neurotransmitter delivery along with neural recording have been demonstrated with these MEAs. Chronic neural interface performance has been sub-optimum. Quantitative histology, explant analysis, and 2-photon imaging revealed biofouling, neuronal damage, inflammation, and oxidative stress at the site of implants, as well as material degradations. We use several bioengineering strategies to minimize these failure modes. First, materials and devices that mimic the mechanical properties of the neural tissue have been developed and shown to significantly improve device-tissue integration. Secondly, biomimetic coatings and drug delivery have been applied to reduce biofouling and inflammatory responses. These approaches may be combined to achieve long-term and high-fidelity multimodal neural interfacing.