Catalytic gold–platinum alloy nanoparticles and a novel glucose oxidase mimic with enhanced activity and selectivity constructed by molecular imprinting†
Gold nanoparticles have attracted a great deal of interest, but also exhibit inherent disadvantages of limited catalytic efficiency and lack of selectivity. Here Au–Pt alloy nanoparticles with significantly improved oxidase-like activity were synthesized, and on this basis, a novel mimic enzyme with substrate-selectivity and further enhanced catalytic efficiency was constructed. According to the exploration of the oxidase-like activities, Au–Pt alloy nanoparticles with a Au–Pt molar ratio of 1 : 1 were found to have the highest catalytic activity due to the combined effects of size and elemental composition. The Au–Pt alloy nanoparticles were coupled to magnetic microspheres to increase the stability and ease of magnetic separation. Besides that, glucose-bindable aminophenylboronic acid was employed to improve the affinity to the substrate and polymerized to build molecularly imprinted polymer shells with specific glucose binding pockets, which successfully led to about 200-fold higher catalytic efficiency (kcat/Km) than gold nanoparticles with an average diameter of 10 nm.