C18 - DNA-Inspired Electrically Conductive Janus Base Nanomaterials for Enhanced Neural Interfacing

Introduction: : Poor integration between brain microelectrodes and local tissue remains a major challenge that inhibits our ability to stimulate and record neural activity for long periods of time. This poor bio-integration is primarily driven by poor biocompatibility and low healthy neuron anchorage post-implantation. The poor acute biological response to intracortical microelectrode implantation often sets the precedent for long term performance. To improve acute- and chronic-term performance of microelectrode integration, attention has shifted towards the development of electrode coatings that attempt to mitigate adverse reactions post-implantation. While device coatings have aimed to improve electrically conductivity and biocompatibility, we see that the improvement of one of these factors typically inhibits the other (a coating that increases electrical conductivity will also diminish its biocompatibility due to cytotoxicity and reactive oxidative species release). Furthermore, a coating that aims to increase device integration through a more bio-friendly material composition will inevitably lead to a decrease in device functionality due to lack of conductivity. The lack of biomimicry in pre-existing electrode coating materials drives the need to develop a biomimetic and electrically conductive coating in order to improve biocompatibility of brain machine interface (BMI) electrodes while maintaining the functionality of the device. Herein, we characterize an innovative electrically conductive coating (JBNc) based on DNA-inspired Janus Base Nanotubes (JBNts) (Figure 1). This study demonstrates the in vitro and in vivo success of this novel biomimetic JBNc through quantitative and qualitative analysis of JBNts on Parylene-C MEAs for enhanced acute neuron attachment response.

Materials and

Methods: : Janus Base Nanotubes (JBNts) are synthesized and self-assembled in aqueous solution by methods previously described. Their electrochemical properties were determined through computational and in vitro methods including voltage sweep, cyclic voltammetry, and impedance spectroscopy. JBNts are deposited onto flexible MEA interfaces through dip-coating methodology, coating the insulation and electrode entirely. Hippocampal implantations and chronic recordings were obtained to assess signal quality over a 4-week period. IHC was performed to assess the biological reaction to JBNt-coated probes compared to in-animal controls.

Results, Conclusions, and Discussions:: Computational modeling supported anisotropic conductivity mechanisms driven by π-π interactions within the nanotube supramolecular structure. Impedance and charge injection values maintained within a functional range, demonstrating effective conduction of electrical signal. Impedance values at varying frequencies further validated electrochemical compatibility of the JBNt nano-coating. Preliminary 4-week implantations provided evidence of preferential neuronal nuclei recruitment to JBNt-coated interfaces leading to a statistically significant reduction in impedance in the acute-phase. Biological assessments in vitro support the increase in neurogenesis mediated by JBNt scaffolding. Immune cell staining confirmed that JBNts did not elicit a foreign body response based on microglia and reactive astrocyte activity.

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