Enhanced Peroxidase Mimetic Activity of Porous Iron Oxide Nanoflakes

Abstract

Porous nanomaterials with superior peroxidase mimetic activity (nanozyme) at room temperature have gained increasing attention as potential alternatives to natural peroxidase enzymes. Herein, we report the application of porous iron oxide nanoflakes (IONFs), synthesized using the combination of solvothermal method and high-temperature calcination as peroxidase nanozyme for the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H 2 O 2 . The four IONF catalysts possess porous structures with a wide pore size distribution between 2-30 nm and high specific surface areas around to 200 m 2 g À1 . The increase of calcination temperature of the IONFs from 250 8C to 400 8C resulted in a gradual decrease in their specific surface area and Michaelis-Menten constant (K m ) for TMB oxidation. The optimum IONF sample showed a much lower K m at 0.24 mM (towards TMB) compared to natural enzyme horseradish peroxidase (HRP) at 0.434 mM, revealing the promising potential of the asprepared IONFs as alternatives to HRP for biosensing applications.[a] Dr.

Vanadium‐Substituted Tungstosulfate Polyoxometalates as Peroxidase Mimetics and Their Potential Application in Biosensing

“…The initial reaction velocity was calculated by Beer-Lambert Law. [27] The apparent kinetic parameters (K m and V max ) for both TMB and H 2 O 2 were estimated by using the Michaelis-Menten and the Lineweaver-Burk equations as outlined in our previous papers for studying enzyme-like activity of goldloaded nanoporous ferric oxide nanocubes, [6,10] porous iron oxide nanoflakes, [5] mesoporous nanocrystalline αor γ-iron oxide, [9] and mesoporous iron oxide. [11]…”

“…Catalysis of TMB by natural peroxidases like HRP, as well as peroxidase mimicking nanozymes, in the presence of H 2 O 2 generates a blue colored 1-electron oxidation product (TMB ox ) which absorbs light at 652 nm and can be used for naked eye evaluation (qualitative) as well as UV-visible (UV-vis) quantification of the reaction. [5,6,9,10] Addition of strong acids to the reaction generates the yellow colored diimine terminal oxidation product which absorbs light at 450 nm and is electroactive. This yellow colored terminal reaction product can be used for UV-vis (semiquantitative, colorimetric), as well as electrochemical quantification.…”

“…This yellow colored terminal reaction product can be used for UV-vis (semiquantitative, colorimetric), as well as electrochemical quantification. [5,6,9,10] The process is illustrated in Figure 1c. Catalytic activity of POMs in H 2 O 2 based epoxidation and oxidation of organic compounds is well established and involves multistep electron transfer reactions.…”

“…These inorganic catalysts can easily convert a colorless enzyme substrate [e. g., 3,3,5,5-tetramethylbenzidine (TMB), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 3,3'-diaminobenzidine (DAB), and o-phenylenediamine dihydrochloride (OPD)] to a colored product while following the principles of natural enzyme (i. e., peroxidase) kinetics. [5][6][7] These so-called peroxidase-like activity of nanostructured materials provides several advantages over natural enzymes, and has widely been employed in developing biomolecule detection platforms. While natural enzymes require strict physiological conditions for optimal performance and involve high costs of synthesis and purification, nanozymes on the other hand are low-cost, highly stable, multifunctional and tunable.…”

Antioxidant Materials Based on 2D Nanostructures: A Review on Recent Progresses

“…Glucose sensing was also achieved through the glucose-GOx reaction with good selectivity amongst other bioactive compounds. Tanaka et al started from Fe 3+ -glycerate precursor and applied thermal treatment to obtain porous Fe 2 O 3 flakes [145]. It was found that lower pyrolysis temperatures resulted in better Fenton-type activity for the synthesized Fe 2 O 3 , since those products had higher surface area and higher hexagonal α-Fe 2 O 3 content with more active sites compared to cubic γ-Fe 2 O 3 ( Table 1).…”