Highly Conductive, Adhesive and Biocompatible Hydrogel for Closed-Loop Neuromodulation in Nerve Regeneration

Developing conductive hydrogels has led to significant advancements in bioelectronics, especially in the realms of neural interfacing and neuromodulation. Despite this progress, the synthesis of hydrogels that simultaneously exhibit superior mechanical stretchability, robust bioadhesion, and high conductivity remains a significant challenge. Traditional approaches often resort to high filler concentrations to achieve adequate electrical conductivity, which detrimentally affects the hydrogel's mechanical integrity and biocompatibility. In this study, we present a multifunctional conductive hydrogel, designated as PAACP, which is engineered from a polyacrylamide-poly(acrylic acid) (PAM-PAA) matrix and enhanced with polydopamine-modified carbon nanotubes (CNT-PDA). This composition ensures an exceptional conductivity of 9.52 S/m with a remarkably low carbon nanotube content of merely 0.33 wt %. The hydrogel exhibits excellent mechanical properties, including low tensile modulus (∼100 kPa), high stretchability (∼1000%), and high toughness (7.33 kJ m^-2). Moreover, the synergistic action of catechol and NHS ester functional groups provides strong tissue adhesive strength (107.14 kPa), ensuring stable bioelectronic-neural interfaces. As a cuff electrode, it enables suture-free implantation and bidirectional electrical communication with the sciatic nerve, which is essential for neuromodulation. Leveraging these capabilities, our hydrogel is integrated into a closed-loop system for sciatic nerve repair, significantly enhancing real-time feedback driven nerve regeneration and accelerating functional recovery. This work offers a strategy for dynamic, personalized neuromodulation in nerve repair and clinical applications.