Fenton-Type and Poulos-Kraut Dual Mechanisms of H<sub>2</sub>O<sub>2</sub> Activation over Peroxidase-Mimicking Nanozymes Identified by <i>Operando</i> Measurements.
basic_science · Level V
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- Record sourced from PubMed, PMID 40875925.
- Also identified by DOI 10.1021/acs.nanolett.5c03455.
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Abstract
Current strategies for developing peroxidase-mimicking nanozymes seldom address the interplay between Fenton-type hemolytic and Poulos-Kraut heterolytic mechanisms in H<sub>2</sub>O<sub>2</sub> activation. To reveal the active centers, reaction intermediates, and dynamic structural transformations during catalysis, we investigated Fe-doped TiO<sub>2</sub> (Fe-TiO<sub>2</sub>) nanozymes that exhibit a dual-mechanism pathway. <i>Operando</i> ambient-pressure electron spin resonance spectroscopy and Raman measurements revealed that H<sub>2</sub>O<sub>2</sub> molecules adsorb onto Fe-TiO<sub>2</sub> surfaces, occupying oxygen vacancy sites (Ti-O<sub>v</sub>-Ti) and forming peroxy bonds with Ti atoms (Ti-OOH). The incorporation of Fe facilitates both Fenton-type homolytic cleavage and Poulos-Kraut heterolytic cleavage of H<sub>2</sub>O<sub>2</sub>, enhancing peroxidase-like activity through interactions between substrates and Ti-OOH intermediates. The inhibitory effect of l-cysteine on the activity of Fe-TiO<sub>2</sub> nanozymes inspired a rapid and selective l-cysteine biosensor. This study reveals that defect engineering introduces the Poulos-Kraut mechanism into peroxidase-mimicking nanozymes as an innovative alternative to the Fenton-type mechanism, offering a promising approach for exploring dual H<sub>2</sub>O<sub>2</sub> activation pathways mimicking natural peroxidases.
Medical subject headings
- Hydrogen Peroxide
- Titanium
- Iron
- Peroxidase
- Nanostructures
- Biomimetic Materials
- Peroxidases