Mussel-inspired ultra-stretchable, universally sticky, and highly conductive nanocomposite hydrogels

Abstract

Developing ultra-stretchable, universally sticky, and highly conductive nanocomposite hydrogels without doping agents and nanoparticle-aggregation is still a challenge. Herein, doping-free and nanoparticle-aggregation-inhibited hydrogels composed of Fe³⁺, dopamine (DA), pyrrole (Py) and polyacrylic acid (PAA) were prepared. Polypyrrole–polydopamine (PPy–PDA)/PAA hydrogels were quickly formed due to the abundant ionic bonds and physical cross-linking under the addition of Fe³⁺. Moreover, the H⁺ ions of the carboxylic acid groups on the PAA polymer chain helped to improve the conductivity of the hydrogels. Surprisingly, the multi-functional hydrogels received a high stretchability of 1900%, a tissue-like elastic modulus of 22 kPa, an adhesive strength of 2125.9 J m⁻², and a high conductivity of 0.39 S m⁻¹. Besides, the PPy–PDA/PAA hydrogels showed good antioxidant activity, biocompatibility and tissue repairing behavior. In short, the prepared multi-functional hydrogels have potential to address the human clinical problem of tissue repair and regeneration.