Heme Cofactor‐Resembling Fe–N Single Site Embedded Graphene as Nanozymes to Selectively Detect H₂O₂ with High Sensitivity

Abstract

Over the past decade, the catalytic activity of nanozymes has been greatly enhanced, but their selectivity is still low and considered a critical issue to overcome. Herein, Fe–N4 single site embedded graphene (Fe–N‐rGO), which resembles the heme cofactor present in natural horseradish peroxidase, shows a marked enhancement in peroxidase‐like catalytic efficiency of up to ≈700‐fold higher than that of undoped rGO as well as excellent selectivity toward target H2O2 without any oxidizing activity. Importantly, when Fe or N is doped alone or when Fe is replaced with another transition metal in the Fe–N4 site, the activity is negligibly enhanced, showing that mimicking the essential cofactor structure of natural enzyme might be essential to design the catalytic features of nanozymes. Density functional theory results for the change in Gibbs free energy during the peroxide decomposition reaction explain the high catalytic activity of Fe–N‐rGO. Based on the high and selective peroxidase‐like activity of Fe–N‐rGO, trace amounts of H2O2 produced from the enzymatic reactions from acetylcholine and cancerous cells are successfully quantified with high sensitivity and selectivity. This work is expected to encourage studies on the rational design of nanozymes pursuing the active site structure of natural enzymes.

Interactions of Fe–N–S Co-Doped Porous Carbons with Bacteria: Sorption Effect and Enzyme-Like Properties

“…[33]. Indeed, it is important to highlight that Fe-N-C nanozymes usually show multienzyme activities [34,35]. However, incorporation of the Fe-N 4 sites into graphene allowed to obtain the material with an exclusive peroxidase-like activity [34].…”

Emerging Multifunctional Single-Atom Catalysts/Nanozymes

“…Besides the catalytic activity, catalytic selectivity and sensitivity are also necessary enzymatic properties for many successful applications. 54 , 55 Lee and colleagues demonstrated that the Fe–N 4 decorated reduced graphene oxide (Fe–N–rGO) can selectively increase the peroxidase-like activity but not the other enzyme-like activity unlike other peroxidase-mimicking nanozymes. 54 Experimental results also confirm that Fe–N–rGO can be used as a sensitive colorimetric probe for extracellular H 2 O 2 detection, which might be further utilized for other biological and biomedical applications.…”

“… 54 , 55 Lee and colleagues demonstrated that the Fe–N 4 decorated reduced graphene oxide (Fe–N–rGO) can selectively increase the peroxidase-like activity but not the other enzyme-like activity unlike other peroxidase-mimicking nanozymes. 54 Experimental results also confirm that Fe–N–rGO can be used as a sensitive colorimetric probe for extracellular H 2 O 2 detection, which might be further utilized for other biological and biomedical applications. Density-functional theory (DFT) calculations confirmed that Fe–N–rGO possesses the lowest reaction barrier for H 2 O 2 formation among the rGO-based nanozymes, thus leading to high selectivity and sensitivity for H 2 O 2 detection.…”

An Enzyme‐Mimicking Single‐Atom Catalyst as an Efficient Multiple Reactive Oxygen and Nitrogen Species Scavenger for Sepsis Management

“…[24][25][26][27][28] Recently, owing to their similar CUS active sites compared to metalloenzymes,S ACsh ave successfully mimicked horseradish peroxidase (HRP), SOD,C AT,a nd oxidase for efficient biosensors,a ntibacterial agents,a nd cytoprotection. [29][30][31][32][33][34][35] These enzyme-mimicking single-atom catalysts (SAzyme) have excellent catalytic activity,and are promising in replacing low-activity nanozymes.O nt he other hand, it has been demonstrated that CNO tend to react fast with the unoccupied coordination position of metalloproteins to form metalnitrosyl complexes. [36] Inspired by this,weenvision that SACs could remove CNO competently and simultaneously mimicked antioxidative enzymes to efficiently scavenge RONS,w hich remains af ormidable challenge for currently nanozymes.…”

“…Single‐atom catalysts (SACs), with coordinatively unsaturated (CUS) active metal centers, have exhibited outstanding performance in diverse catalytic reactions . Recently, owing to their similar CUS active sites compared to metalloenzymes, SACs have successfully mimicked horseradish peroxidase (HRP), SOD, CAT, and oxidase for efficient biosensors, antibacterial agents, and cytoprotection . These enzyme‐mimicking single‐atom catalysts (SAzyme) have excellent catalytic activity, and are promising in replacing low‐activity nanozymes.…”