Implantable Multi-Cross-Linked Membrane-Ionogel Assembly for Reversible Non-Faradaic Neurostimulation

Abstract

Neural interfaces play a major role in modulating neural signals for therapeutic purposes. To meet the demand of conformable neural interfaces for developing bioelectronic medicine, recent studies have focused on the performance of electrical neurostimulators employing soft conductors such as conducting polymers and electronic or ionic conductive hydrogels. However, faradaic charge injection at the interface of the electrode and nerve tissue causes irreversible gas evolution, oxidation of electrodes, and reduction of biological ions, thus causing undesired tissue damage and electrode degradation. Here we report a conformable neural interface engineering based on multicross-linked membrane−ionogel assembly (termed McMiA), which enables nonfaradaic neurostimulation without irreversible charge transfer reaction. The McMiA consists of a genipin-cross-linked biopolymeric ionogel coupled with a dopamine-cross-linked graphene oxide membrane to prevent ion exchange between biological and synthetic McMiA ions and to function as a bioadhesive forming covalent bonds with the target tissues. In addition, the demonstration of bioelectronic medicine via the McMiA-based neurostimulation of sciatic nerves shows the enhanced clinical utility in treating the overactive bladder syndrome. As the McMiA-based neural interface is soft, robust for bioadhesion, and stable in a physiological environment, it can offer significant advancement in biocompatibility and long-term operability for neural interface engineering.

Permeable Bioelectronics toward Biointegrated Systems

“…The oxidation of metallic materials is a significant concern for the long-term implantation of electrical conductor-based bioelectronics because biofluids contain large amounts of water and ions. , Although Ag NWs have the potential to be utilized in bioelectronics owing to their high conductivity and stretchability, they are highly corroded in biological environments, which limits their in vivo applications. To prevent the degradation of bioelectronics, which also causes tissue damage, Choi et al reported Ag–Au nanocomposites composed of ultralong Au-coated Ag NWs in a poly­(styrene–butadiene–styrene) (SBS) elastomer (Figure F) .…”