Nanozymes are catalytically active nanomaterials that can mimic the catalytic properties of natural enzymes. However, little research has focused on nanozymes for mimicking organophosphate hydrolase (OPH) activity. Herein, we report that the zeolitic imidazolate framework-90 (ZIF-90) nanoparticles synthesized by the self-assembly of imidazole and metal ions have an average size of about 800 nm. They can serve as a new nanozyme to mimic OPH, which can effectively hydrolyze organophosphorus methyl parathion. More importantly, the asprepared ZIF-90 nanozyme shows higher stability and superior recyclability. Our work will bring new possibilities for design and development of other novel nanozymes based on metal−organic framework materials.

Since Fe 3 O 4 nanoparticles were first reported to possess intrinsic peroxidase-like activity in 2007, [1] tremendous efforts have been made to constructing nanozymes. They can imitate the extraordinary activities of natural enzymes in biocatalytic chemistry and overcome their shortcomings like poor stability and high cost. [2-5]

Light-activated nanozymes can provide a wealth of new opportunities for the chemical industry and biotechnology. However, present remote-controlled catalytic systems are still far from satisfactory. Herein, we present an interesting example of applying ultrathin Pd nanosheets (Pd NSs) as a light-controllable peroxidase mimic. Since most of Pd atoms are exposed on their surface, Pd NSs with a thickness of 1.1 nm possess high peroxidase-like activity. More importantly, under light excitation, such intrinsic activity can be further activated by a nearly 2.4-to 3.2-fold. Such a phenomenon can be ascribed to the unique optical property of ultrathin Pd NSs, which can efficiently capture photons to generate hot electrons via surface plasmon resonance effect and thus promote the in situ decomposition of H 2 O 2 into reactive oxygen species radicals (O*). This enhanced catalysis can also be used for realtime and highly sensitive colorimetric detection of H2O2. We expect our work can provide valuable insights into the rational design of artificial nanozymes with controllable and efficient activity in biomedical diagnostics, drug delivery, and environmental chemistry.

The development of artificial enzymes with excellent enzyme‐like activities and unique features is highly desirable for their practical applications. Herein, a one‐pot facile method to synthesize hemin covalently functionalized carbon nanobranch (CN‐hemin) via direct pyrolysis of citric acid and covalent coupling of hemin to the formed carbon skeleton, is reported. This strategy is reasonably straightforward, cheap, and environmentally friendly, without any extraneous oxidant, reductant, and harmful additives during the preparation process. Furthermore, the obtained dendritic hybrids possess good water‐solubility, intrinsic peroxidase‐like activity, and satisfactory photocatalytic performance in visible light. These extraordinary properties are mainly due to the structure of CN‐hemin which contains iron porphyrin, aromatic carbon, and citric acid residues. Most importantly, under visible light irradiation, the as‐prepared hemin‐incorporated nanohybrid can act as robust agents for synergistic dye degradation and antibacterial therapy toward Staphylococcus aureus and methicillin‐resistant S. aureus. It is expected that this study can shed valuable light on developing advanced multifunctional nanozymes with combined favorable properties for highly efficient elimination of environmental pollutants and antibacterial treatment.

No abstract