Peroxidase mimic activity of hematite iron oxides (α-Fe2O3) with different nanostructres

Enzyme mimics have garnered considerable attention as they can overcome some serious disadvantages associated with the natural enzymes. In recently developed sphere and rod shaped iron oxide peroxidase mimic nanoparticles, the influence of physical parameters such as shape, size and surface area on the catalytic performance was not clearly demonstrated. In order to better understand the influence of physical parameters on the enzyme mimic activity of iron oxide nanoparticles, the present study was initiated using three different shaped hematite alpha-Fe2O3 nanostructures, particularly hexagonal prism, cube-like and rods as model systems. A comparative account of kinetic parameters (K-m, V-max and K-cat) of the peroxidase mimic activity by the various alpha-Fe2O3 nanostructures indicated that the enzymatic potential of these nanoparticles increased from hexagonal prism to rods, via cube-like, suggesting that one-dimensional particles act as a more efficient enzyme mimic system compared to their multi-dimensional counterparts. Surface area is likely to be a key physical aspect responsible for the enzyme mimic activity. Interestingly, however, particles with lower surface area showed better catalytic performance in the case of one-dimensional rod structure. Upon further analysis of the one-dimensional rods, additional physical properties such as porosity and pore shape also seem to have a significant contribution to their catalytic activity.