The peroxidase‐like activity of nanozymes is promising for chemodynamic therapy by catalyzing H2O2 into .OH. However, for most nanozymes, this activity is optimal just in acidic solutions, while the pH of most physiological systems is beyond 7.0 (even >8.0 in chronic wounds) with inadequate H2O2. We herein communicate an activatable nanozyme with targeting capability to simultaneously break the local pH and H2O2 limitations under physiological conditions. As a proof of concept, aptamer‐functionalized nanozymes, glucose oxidase, and hyaluronic acid constitute an activatable nanocapsule “APGH”, which can be activated by bacteria‐secreted hyaluronidase in infected wounds. Nanozymes bind onto bacteria through aptamer recognition, and glucose oxidation tunes the local pH down and supplements H2O2 for the in‐situ generation of .OH on bacteria surfaces. The activity switching and enhanced antibacterial effect of the nanocapsule were verified in vitro and in diabetic wounds. This strategy for directly regulating local microenvironment is generally accessible for nanozymes, and significant for facilitating biological applications of nanozymes.

The Au À S bond is the classic way to functionalize gold nanoparticles (AuNPs). However, cleavage of the bond by biothiols and other chemicals is a long-standing problem hindering practical applications, especially in cells. Instead of replacing the thiol by a carbene or selenol for stronger adsorption, it is now shown that the Pt À S bond is much more stable, fully avoiding cleavage by biothiols. AuNPs were deposited with a thin layer of platinum, and an AuNP@Pt-S nanoflare was constructed to detect the miRNA-21 microRNA in living cells. This design retained the optical and cellular uptake properties of DNA-functionalized AuNPs, while showing high-fidelity signaling. It discriminated target cancer cells even in a mixed-cell culture system, where the Au-S based nanoflare was less sensitive. Compared to previous methods of changing the ligand chemistry, coating a Pt shell is more accessible, and previously developed methods for AuNPs can be directly adapted.

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