Injectable Conductive Hydrogels with Tunable Degradability as Novel Implantable Bioelectrodes

Area of Science:

• Biomaterials Science
• Neuroscience
• Electrical Engineering

Background:

• Bioelectrodes are crucial for interfacing with biological systems, but in vivo longevity remains a challenge.
• Conductive hydrogels offer tissue-like properties and conformal contact for bioelectrode applications.
• Existing bioelectrode administration and control over lifespan present significant hurdles.

Purpose of the Study:

• To develop injectable conductive hydrogels (ICHs) with tunable degradability for implantable bioelectrode applications.
• To investigate the material properties, biocompatibility, and in vivo performance of ICHs.
• To demonstrate the potential of ICHs for enhanced signal recording in bioelectronics.

Main Methods:

• Synthesized ICHs using thiol-ene reactions with reduced graphene oxide and either hydrolyzable or stable poly(ethylene glycol) crosslinkers.
• Characterized the conductivity, mechanical properties (Young's modulus), and biocompatibility of the hydrogels.
• Evaluated the in vivo degradation profile and electromyography (EMG) signal recording capabilities in a rat model.

Main Results:

• ICHs exhibited conductivities of 21-22 mS cm⁻¹ and Young's moduli of 15-17 kPa, with excellent cell and tissue compatibility.
• Hydrolyzable ICHs degraded within 3 days in vivo, while stable ICHs remained intact for up to 7 days.
• Injected ICH electrodes demonstrated significantly improved EMG signal sensitivity compared to skin and nonconductive hydrogel electrodes.

Conclusions:

• Injectable conductive hydrogels with tunable degradation offer a promising platform for advanced bioelectronics.
• ICHs provide convenient administration, controlled in vivo lifetime, and excellent electrical signal transmission.
• These findings highlight the potential of ICHs for developing next-generation bioelectronic devices.