Size- and shape-dependent peroxidase-like catalytic activity of MnFe2O4 Nanoparticles and their applications in highly efficient colorimetric detection of target cancer cells

Abstract

The catalytic activity of nanocrystal catalysts depends strongly on their chemical composition, size, and shape. Herein, we report four different sizes and shapes of MnFe₂O₄ nanoparticles (NPs) prepared by a hydrothermal procedure. In addition, the size- and shape-dependent peroxidase-like activity of these NPs was first explored using 3,3′,5,5′-tetramethyl-benzidine and H₂O₂ as peroxidase substrates. The results showed that the peroxidase-like activities of the MnFe₂O₄ NPs were size- and shape-dependent and followed the order of 4 nm (spherical) > 18 nm (plate-like) > 27 nm (near-cubic) > 16 nm (spherical); this order was closely related to their surface-to-volume ratio and atom arrangements. Such an investigation is of great significance for peroxidase nanomimetics with enhanced activity and utilization. Furthermore, folic acid (FA)-conjugated MnFe₂O₄ NPs allow the detection of folate receptor-rich cancer cells. Such investigation can be widely utilized for the identification of important target molecules.