Nanoconfining Cation-π Interactions as a Modular Strategy to Construct Injectable Self-Healing Hydrogel

Cation-pi interaction is considered one of the strongest noncovalent interactions in aqueous solutions, which endows natural biomolecules (e.g., proteins) with ro-bust wet adhesion and cohesion in humid/underwater environments. However, it remains a challenge to con-struct synthetic functional materials (e.g., self-healing hydrogels) by adopting the cation-pi interactions ratio-nally. Herein, we present a facile and novel strategy to fabricate injectable self-healing synthetic hydrogel from self-assembly of a thermoresponsive ABA tri-block copolymer via cation-pi interactions. This triblock comprised a modified poly(N-isopropylacrylamide) (PNIPAM) incorporated with cationic and aromatic components as the A block and a hydrophilic poly (ethylene oxide) (PEO) as B block. Upon thermally induced gelation, the cationic and aromatic compo-nents are closely and densely packed into nanocon-fined micelles to provide reversible and strong cation-pi interactions, thereby endowing the resulting hydrogel with an eye-catching self-healing performance upon the hydrogel damage. The hydrogel also exhibited an excellent thermoresponsive reversible sol-gel transition and clear shear-thinning property that offers the developed hydrogel injectability. This work demon-strates a new strategy for developing self-healing materials by incorporating cation-pi interaction that renders various engineering and bioengineering appli-cations. [GRAPHICS] .

Automated summary

Cation-pi interaction is a strong noncovalent interaction in aqueous solutions, which provides natural biomolecules with robust wet adhesion and cohesion. Constructing synthetic materials with cation-pi interactions has been a challenge. In this study, the authors developed an injectable self-healing synthetic hydrogel by self-assembling a thermoresponsive ABA triblock copolymer via cation-pi interactions. The hydrogel exhibited excellent self-healing performance, thermoresponsive sol-gel transition, and shear-thinning property, making it suitable for various engineering and bioengineering applications.