Free-Radical Formation by the Peroxidase-Like Catalytic Activity of MFe₂O₄ (M = Fe, Ni, and Mn) Nanoparticles

Abstract

Ferrite Magnetic Nanoparticles (MNPs) have peroxidase-like activity and thus catalyze the decomposition of H 2 O 2 producing reactive oxygen species (ROS). Increasingly important applications of these Ferrite MNPs in biology and medicine require that their morphological, physicochemical and magnetic properties need to be strictly controlled. Usually, the tuning of their magnetic properties is achieved by the replacement of the Fe by other 3d metals, such as Mn or Ni. Here, we studied the catalytic activity for ferrite MNPs (MFe 2 O 4 , M = Fe 2+ /Fe 3+ , Ni, Mn) with mean diameter ranging from 10 to 12 nm. Peroxidase-like activity was studied by Electron Paramagnetic Resonance (EPR) using the spin-trap DMPO at different pHs (4.8, 7.4) and temperatures (25°C, 40°C). We identified an enhanced amount of the hydroxyl (•OH) and perhydroxyl (•OOH) radicals for all samples, compared to a blank solution. Quantitative studies show that [•OH] is the dominant radical formed for Fe 3 O 4 , which is strongly reduced with the concomitant oxidation of Fe 2+ or its substitution (Ni or Mn). A comparative analysis of the EPR data against in vitro production of ROS in microglial BV2 cell culture provided additional insight regarding the catalytic activity of ferrite MNPs, which should be considered if biomedical uses are intended. Our results contribute to a better understanding of the role played by different divalent ions in the catalytic activity of Ferrite nanoparticles, which is very important concerning their use in biomedical applications.

Interplay between inter- and intraparticle interactions in bi-magnetic core/shell nanoparticles

“…The ferrites CoFe 2 O 4 (CFO) and NiFe 2 O 4 (NFO) were chosen due to the increasing interest in their applications (e.g., biomedicine, catalysis, etc. [26,27]) as well as the significant difference between the magnetocrystalline anisotropy, K V NFO = −6.2 × 10 3 J/m 3 and K V CFO = 2 × 10 5 J/m 3 , and the relatively high value of their magnetisation M S (M S CFO = 88 A•m 2 /kg and M S NFO = 55 A•m 2 /kg) [28,29]. While most works deal with iron oxides or Mn/Zn substituted ferrites as a soft phase, only a few works are devoted to nickel ferrite in core/shell systems [4,14,30], although nickel ferrite being a promising material for catalysis [31] and spintronics [32] applications.…”

Surface-Textured Mixed-Metal-Oxide Nanocrystals as Efficient Catalysts for ROS Production and Biofilm Eradication

“…In contrast, the presynthesized surfactant-free Fe 3 O 4 and Co 3 O 4 NCs failed to show any noticeable reaction (Figure 2c). 4,8,17 2d). 8 At pH 7.4, the ROS generation by MTex-500 was found to be an impressive ca.…”

“…8 Therefore, such catalysts exhibit feeble efficacy and often require complex formulations with abiotic acidic conditions, multiple enzymes, or applications of photothermal effects, photosensitizers, and other physical methods 9−13 to function in the complex and stressful chemical conditions found in biofilms. 14,15 The catalytic activities of nanocrystals (NCs) can be improved by controlling the NC shapes/sizes, 16 compositions, 17 facets, 18,19 heterointerfaces, 20 and surface ligands. 21,22 Conventional NCs are still far inferior to the ingeniously evolved enzymes, and control of their intricate surface features for optimal exposure of active sites is quite challenging.…”

Depletable Peroxidase-like Activity of Fe3O4 Nanozymes Accompanied with Phase Transformation Triggered by Separate Migration of Electron and Iron Ion

“…3,4 Despite being a pioneering nanozyme, research on the catalytic mechanism of the POD-like activity of Fe3O4 NPs is still limited. 10,[14][15][16][17][18][19] To date, it is generally accepted that high-reactive hydroxyl radicals (•OH) generated by Fenton-like reactions (Equation 1-2) involving the surface Fe 2+ under acid conditions contributes to the POD-like activity of Fe3O4 NPs. 18,19 Similar to natural horseradish peroxidase (HRP), Fe3O4 nanozymes follow the ping-pong mechanism and Michaelis-Menten kinetics.…”

“…10 Besides, their catalytic performances are influenced by particles size, morphology, lattice structure, doping, surface modification, substrates used, as well as the catalytic environment exposed, all of which could affect the surface active sites by altering the surface chemistry. 10,16,17,[20][21][22][23] Other individual studies have investigated the absorption, activation, and desorption processes of substrates (e.g. H2O2 and TMB) on the surface of Fe3O4 at the atomic level based on density functional theory and developed some descriptors to predict their POD-like activity.…”