Synchronizing Tunable Luminescence and Shape Morphing in a Metal Nanocluster-Enabled Hydrogel Platform.

Abstract

Soft hydrogels capable of simultaneous shape morphing and optical modulation under a single stimulus hold promise for next-generation intelligent materials. However, most systems rely on complex architectures or multi-component triggers, limiting integration and responsiveness. Here, we develop a structurally homogeneous nanocluster-gel platform by embedding water-soluble gold nanoclusters (AuNCs) into a polyacrylamide matrix, enabling synchronized mechanical deformation and tunable luminescence in response to solvent polarity. Upon exposure to organic solvents, the gel rapidly contracts (<5 s), while spatial confinement of AuNCs within the polymer boosts quantum yield from 6.05% to 22.83%. The emission profile is programmable by varying cluster size, highlighting AuNCs as structurally tunable emission modulators. Kinetic analysis reveals non-Fickian swelling/deswelling-governed by solvent diffusion and polymer relaxation-that synergistically modulates emission. This enables real-time, quantitative optical detection of solvent gradients (R² = 0.996) with >97% reversibility over 10 cycles. The integrated responsiveness is demonstrated in a biomimetic lotus-shaped gel that folds and dims upon water uptake, and is further validated in a leakage scenario where the hydrogel serves as a pipe encapsulation film, achieving rapid sealing and visual monitoring of solvent leakage. This work establishes a nanocluster-gel platform that unifies photophysics and actuation for adaptive, self-indicating soft systems.