A viologen-based conductive hydrogel enables iontophoresis devices powered by Mg biobattery

Conductive hydrogels with both electrical responsiveness and drug loading capability are emerging as promising platforms for on-demand drug delivery systems to incorporate electron signals as biorelevant physical cues. However, conventional conductive hydrogels based on conducting polymers and carbon-based nanomaterials suffer from low conductivity and insufficient responsiveness to electrical stimuli, thus requiring high voltages to induce drug delivery. Herein, we develop a viologen-based conductive hydrogel via multiple dynamic interactions, including hydrogen bonds and boronate ester bonds. The cytocompatible and antibacterial hydrogel forms an intimate bioelectronic interface with skin tissue, including high ionic conductivity, low contact impedance, high toughness, and seamless adhesion. It offers a fast response to electrical signals and high release efficiency (65.8%) at a low voltage (-1.0 V). Further, a Mg biobattery powered-iontophoresis using the hydrogel as an integrated drug-carrying electrode demonstrates a stable and effective drug release, enabling high-dosage administration for long-period operation. This iontophoresis device provides new therapeutic approaches for chronic skin diseases requiring daily or precise drug delivery in a non-invasive way.