Hybrid neural interfacing devices based on Au wires with nanogranular Au shell and hydrogel layer for anti-inflammatory and bi-directional neural communications

Realizing a long-duration stable electrical contact with peripheral nerves in vivo is challenging due to the fragility and tubular shapes of peripheral nerves and the foreign body response caused by implanted devices at the nerve -device interface. Herein, we report the development of a hybrid neural interfacing device (HNID) based on Au wires with a nanogranular Au shell and hydrogel layer used to achieve a non-inflammatory, stable, and bi-directional bioelectronic interface with peripheral nerves. A natural hydrogel made up of genipin-crosslinked gelatin is developed to produce a three-dimensional network structure displaying excellent biocompatibility, sufficient ionic conductivity, and durable mechanical property. Neural electrodes based on Au wires with a nanogranular Au shell enable effective ionic/electrical coupling and neural communication with the nerve through the hydrogel layer. In in vivo studies involving rats, an implanted HNID suppresses the inflammatory response and fibrosis and causes negligible damage to the sciatic nerve, enabling stable stimulation of the nerve and recording of the neural signal of the sciatic nerve for 15 days after implantation. Our approach could extend the applicability of various inorganic electrode materials for the development of nerve-interfacing bioelectronics displaying high performance and long-term stability.