Catalytically active nanohybrid gel beads for heterogeneous Suzuki-Miyaura cross-coupling and peroxidase-mimicking catalytic activity.

Supramolecular hydrogels exhibit great potential as catalytic soft matter, as their dynamic, porous nature facilitates reagent diffusion and enhances catalyst-substrate interactions. Immobilizing canonical catalytic nanomaterials in a gel matrix induces confinement, suppressing nanoparticle aggregation, and preserving the catalyst. When further engineered into spherical bead-like architectures, these nanohybrid gels offer high surface area, facile recyclability, scalability, and convenient handling. Despite this significant prospect, developing nanohybrid gel beads that integrate conventional synthetic catalysis with enzyme-like functions within a single, reusable platform remains challenging. Herein, we report core-shell nanohybrid hydrogel beads that generate and stabilize catalytically active Pd and Pt nanoparticles in situ via a simple, green strategy. The beads are fabricated from an amino-acid-derived supramolecular hydrogel encapsulated within an alginate shell, wherein the amino-acid nanofibers facilitate metal-ion sequestration, reduction, and stabilization without external reducing or capping agents, while the alginate shell imparts structural robustness, preserves bead integrity, regulates mass transport, and prevents nanoparticle leaching. The Pd-loaded beads exhibited excellent catalytic activity for Suzuki-Miyaura cross-coupling under mild, open-air conditions, maintaining exceptional reusability over multiple cycles. Remarkably, the Pd beads addressed one of the longstanding challenges in Pd-catalyzed Suzuki-Miyaura cross-coupling: the efficient formation of C-C bonds in the presence of sulfur-containing substituents. The system also demonstrated excellent tolerance toward coordination-induced deactivation, underscoring its resistance to poisoning by Lewis-basic amines. In parallel, Pd- and Pt-loaded beads exhibited efficient peroxidase-like activity with high reusability. Collectively, this work establishes supramolecular core-shell nanohybrid hydrogel beads as versatile soft catalytic platforms for integrated synthetic and biomimetic catalytic applications.