High Reusability of Catalytically Active Gold Nanoparticles Immobilized in Core–Shell Hydrogel Microspheres

[Image: see text] The reusability of hybrid core–shell microgels, whose core surfaces were decorated with gold nanoparticles, was investigated in terms of catalysis activity. Hybrid core–shell microgels composed of a rigid core and water-swollen gel shell endowed the immobilized gold nanoparticles with a high dispersion stability, which resulted in excellent catalytic activity. In contrast to free Au nanoparticles and conventional hybrid microgels, where the Au nanoparticles are randomly distributed over the entire microgel templates, the hydrogel shell part of the hybrid core–shell microgels suppressed the aggregation between the microgels and Au nanoparticles in individual microgels, which improved the reusability for the catalysis reaction. The results of this study should help to develop advanced catalyst systems that require high reusability even when the chemical reactions occur in aqueous solution and external stimuli are applied.