In situ generation of H 2 O 2 using CaO 2 as peroxide storage depot for haloperoxidase mimicry with surface-tailored Bi-doped mesoporous CeO 2 nanozymes.

Designing the size, morphology and interfacial charge of catalyst particles at the nanometer scale can enhance their performance. We demonstrate this with nanoceria which is a functional mimic of haloperoxidases, a group of enzymes that halogenates organic substrates in the presence of hydrogen peroxide. These reactions in aqueous solution require the presence of HO. We demonstrate generation of HO from a CaO reservoir in polyether sulfone (PES) and poly(vinylidene fluoride) (PVDF) polymer beads, which circumvents the external addition of HO and expands the scope of applications for haloperoxidase reactions. The catalytic activity of nanoceria was enhanced significantly by Bi substitution. Bi-doped mesoporous ceria nanoparticles with tunable surface properties were prepared by changing the reaction time. Increasing reaction time increases the surface area of the mesoporous BiCeO nanoparticles and the Ce/Ce ratio, which is associated with the -potential. In this way, the catalytic activity of nanoceria could be tuned in a straightforward manner. HO required for the reaction was released steadily over a long period of time from a CaO storage depot incorporated in polyether sulfone (PES) and poly(vinylidene fluoride) (PVDF) beads together with BiCeO particles, which may be used as precision fillers and templates for biological applications. The spheres are prepared as a dry powder with no surface functionalization or coatings. They are inert, chemically stable, and safe for handling. The feasibility of this approach was demonstrated using a haloperoxidase assay.