Cu/Zr Metal–Organic Frameworks with High Peroxidase-Like Activity for Sensitive Electrochemical and Colorimetric Dual-Mode Detection of Hydrogen Peroxide Released from Living Cells

Hydrogen peroxide (H 2 O 2 ) is closely associated with various diseases and is commonly used as a target for disease diagnosis and treatment, making research on H 2 O 2 detection methods crucial. Compared to currently used single-mode detection methods, dual-mode detection offers self-validation and self-correction capabilities, which help to provide more accurate detection results. Herein, an electrochemical and colorimetric dual-mode sensing platform was developed to detect H 2 O 2 based on copper/zirconium metal–organic framework (Cu/Zr-MOF) nanozymes with high peroxidase-like activity. Cu/Zr-MOF catalyzes the reduction of H 2 O 2 to generate ·OH, which oxidizes colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into a blue product (oxTMB), and the color change can be recognized and measured using a smartphone application. Furthermore, Cu/Zr-MOF exhibits excellent electrocatalytic reduction activity toward H 2 O 2 . Electrochemistry demonstrated higher sensitivity with a detection limit as low as 21.3 nM, compared to colorimetry (0.11 μM). The effective combination of the two detection modes allows the sensing platform to exhibit high accuracy, selectivity, and reliability. The dual-mode sensing platform opens a pathway for the accurate and sensitive detection of intracellular and extracellular H 2 O 2 and has a broad spectrum of applications in pathological research and disease diagnosis.