Dual-Nanozyme Cascade for System-Wide Specific Colorimetric Detection of Aminoglycoside Antibiotics

Antibiotic contamination has been a significant concern in environmental monitoring. Nanozyme-based colorimetric sensors can provide valuable support for in-field detection. However, the development of sensing elements capable of identifying an entire class of specific antibiotics using a single material poses a considerable challenge. In this work, we present a compartmentalized dual-nanozyme cascade composite (Au@mPDA/PAA-Cu2MI, AmPC) designed for the colorimetric detection of aminoglycoside antibiotics (AGs), and we analyze the catalytic mechanisms of the dual-enzyme system in detail. The AmPC composite possesses both analogue glucose oxidase-like (aGOx-like) and peroxidase-like (POD-like) activities. In this process, AGs with a sugar structure can serve as the initial substrate of the reaction, while the resulting H₂O₂ acts as the second substrate for colorimetric detection. Using gentamicin (GMC) as a proof of concept, we established a detection range of 0.1–10 μg/mL, with a detection limit (LOD) of 91 ng/mL. In addition, we validated the colorimetric response for other AGs and employed principal component analysis (PCA) for differentiating among various AGs. This approach enables nanozymes to selectively recognize their targets through a cascade mechanism. Furthermore, it facilitates the simultaneous detection and identification of antibiotics, highlighting its potential for in-field applications.