Nanoconfinement-Guided Construction of Nanozymes for Determining H 2 O 2 Produced by Sonication.

Nanomaterials with enzyme-like activities, termed as nanozymes, have found wide applications in various fields. It has been a long-term aim to rationally design and synthesize highly active nanozymes and thus to further improve their application performance. Guided by the nanoconfinement effect, we confine cytochrome c (Cyt c) within a mesoporous metal-organic framework (MOF), PCN-222 nanoparticle (NP), forming a protein/MOF hybrid nanozyme, termed as Cyt c@PCN-222 NP. The confined Cyt c exhibits around 3-4-fold higher peroxidase-like activity than free Cyt c. Due to the increase in the activity of Cyt c, the Cyt c@PCN-222 NPs exhibit a quite low limit of detection (≈0.13 μM) towards H 2 O 2 . Sonication-induced H 2 O 2 formation in water by using a lab-quipped ultrasonic cleaner can be sensitively probed, which suggests that H 2 O 2 -sensitive materials should be carefully handled during the utilization of ultrasonic equipment. We speculate that this nanoconfinement strategy can broaden our synthetic methodology for the rational design of nanozymes.