Gold nanorods crosslinking PNIPAM hydrogels via dynamic Au-thiolate interaction with stretchable, adhesive, self-healing, and photothermal properties

Abstract

Gold nanorod (AuNR) nanocomposite hydrogels have attracted increasing attention due to the photothermal effect of AuNRs. However, a facile strategy that avoids multi-step surface modification for synthesis of AuNR crosslinkers is still a critical challenge. Here, AuNRs crosslinking PNIPAM hydrogels were prepared by polymerization of NIPAM with N,N′-bis(acryloyl)cystamine (BACA)-modified AuNRs as crosslinkers. BACA contains a disulfide bond in the structure. Dynamic and reversible Au-thiolate bonding was formed by directly mixing AuNRs and BACA to facilely prepare AuNR crosslinkers before hydrogel formation. The addition of AuNRs gives hydrogels their photothermal effect and remarkable mechanical behaviors. Hydrogels could repeatedly adhere to the surface of pigskin, metal, plastic, and glass with a relatively stable adhesion. The damaged hydrogels heal within 2 min with near-infrared (NIR) laser (808 nm, 300 mW∙cm⁻²) irradiation. This work provides a line of thinking for improvement of PNIPAM hydrogels, making them promising for further applications in biomedicine.