Immobilization of ruthenium nanoparticles on magnetic hollow mesoporous carbon spheres and investigation of peroxidase-like activity in the oxidation of amine compounds

Background: Nanoenzymes with properties such as stability, high catalytic activity, easy recycling, and low cost have been subjected to considerable research to develop new enzyme-like heterogeneous catalysts. Carbon supports are very important in the construction of heterogeneous catalysts due to their biocompatibility and proper interaction with organic reactants. Methods: In this study, ruthenium nanoparticles were immobilized on magnetic hollow mesoporous carbon spheres. At first, hollow mesoporous carbon structures were synthesized by Stober's method. Through carbonization and subsequent etching with NaOH, the synthesized structures were transformed into hollow mesoporous spherical carbon structures. These hollow carbon spheres have been transformed into magnetic hollow carbon spheres after being impregnated with iron ions, freeze-drying, and then calcinated under inert conditions. Finally, these spheres were immobilized with ruthenium metal nanoparticles by wet chemical reduction. Significant Findings: The peroxidase-like activity of the synthesized nanocomposites was evaluated in the oxidation of amine chromatic compounds of dopamine, ortho-phenylenediamine, and tetramethylbenzidine. Based on the results, these compounds have a lower Michaelis constant constant than hydrogen peroxide, which indicates a strong tendency to the enzymatic reaction. This high reactivity of the synthesized catalyst can be attributed to the synergistic effects of magnetite and ruthenium nanoparticles as well as the role of the carbon support.