Neural interfaces play a crucial role in understanding brain disorders and developing effective treatments. However, maintaining the stability and biocompatibility of neural electrode interfaces over long periods remains a challenge. In a recent study published in ACS Applied Materials & Interfaces, Prof. Lu Yi and his research group from the Shenzhen Institute of Advanced Technology proposed a novel approach using three-dimensional (3D) conductive polymer-hydrogel interpenetrating networks.
Poly (3,4-ethylenedioxythiophene), or PEDOT, is a commonly used modified conductive polymer material known for its biocompatibility and low electrochemical impedance. However, PEDOT films often develop cracks or delaminations, limiting their electrochemical and mechanical stability. To overcome this challenge, the researchers introduced a unique interface modification strategy.
The researchers utilized a pre-coating technique using a polystyrene sulfonate/polyvinyl alcohol (PSS/PVA) hydrogel film, which was applied to the surfaces of a microelectrode array, creating a 3D scaffold rich in counter ions. Subsequently, they electropolymerized the 3,4-ethylene dioxythiophene monomer within the PSS/PVA scaffold, forming an interpenetrating conducting polymer network (ICPN). This ICPN exhibited a highly porous microstructure, optimizing mechanical energy dissipation, adhesion, and long-term stability of the conducting hydrogel coatings.
The resulting ICPN film demonstrated a 3D highly porous microstructure with pore sizes ranging from 0.1 to 1.0 μm. This unique structure greatly contributed to its low Young’s modulus of 191 kPa and remarkable stretchability of 72%. Furthermore, the ICPN film exhibited low electrochemical impedance, high capacitance, and exceptional biocompatibility, making it suitable for a wide range of in-vivo applications in neural interfaces.
To evaluate the effectiveness of the ICPN-modified interfaces, the researchers conducted a comparative analysis with PEDOT/PSS film-modified neural electrode arrays. After 12 weeks of implantation into the mouse hippocampus, the ICPN-modified interfaces demonstrated significant enhancements in the quality of signals during chronic electrophysiological recordings. These findings hold promise for expanding the applications of neural implants and providing valuable insights into the diagnosis and treatment of neuropsychiatric disorders.
The research group led by Prof. Lu Yi has introduced a remarkable innovation in the field of neural interfaces. The utilization of three-dimensional conductive polymer-hydrogel interpenetrating networks offers a solution to the challenges faced by traditional neural electrode interfaces. The highly porous microstructure, mechanical stability, and biocompatibility of the ICPN film make it a promising material for long-term use in various in-vivo applications. This research opens new avenues for improving the understanding and treatment of brain disorders in the future.