Layer-by-layer growth of molecular-sieving ZIF-8 thin film on AuPt nanoparticles for highly selective electrochemical detection of H2O2 in cancer cells

The development of highly selective enzyme-free electrochemical sensors remains challenging, particularly in complex biological environments containing multiple electroactive interferents. To address this issue, we present a hierarchical sensing interface by innovatively growing a zeolitic imidazolate framework-8 (ZIF-8) film on three-dimensional AuPt nanoalloys. This design capitalizes on the molecular sieving effect of ZIF-8, which allows selective permeation of H 2 O 2 to the underlying catalytic AuPt surface while effectively blocking larger interferents such as ascorbic acid, uric acid, and dopamine. The resulting sensor exhibits exceptional selectivity, enabling accurate detection of H 2 O 2 even in the presence of interferents at concentrations 20-fold higher. Moreover, through the controllable growth of the ZIF-8 film and the high catalytic activity of the AuPt nanoalloy, the optimized sensor also demonstrates high sensitivity, a wide linear range, and a low detection limit. It was also successfully applied to in situ tracking of H 2 O 2 release from live cervical and breast cancer cells. This work provides a novel strategy for constructing metal-organic framework-based heterostructures for highly selective sensing, paving the way for reliable H 2 O 2 monitoring in biomedical applications.