A synergistic ZIF-8/RGO/Pt nanozyme sensor for sensitive electrochemical detection of H2O2 and real-time monitoring of oxidative stress in zebrafish embryos

A high-performance nanozyme electrochemical sensor was engineered for the sensitive detection of hydrogen peroxide (H 2 O 2 ). The sensor is based on a synergistic ternary nanocomposite of ZIF-8, reduced graphene oxide (RGO), and platinum nanoparticles (Pt NPs). In this design, the Pt NPs serve as the catalytic centers with intrinsic peroxidase-like activity, effectively mimicking natural enzymes to catalyze the electrochemical reduction of H 2 O 2 . This nanocomposite was immobilized on a glassy carbon electrode (GCE) via a combined drop-casting and electrodeposition strategy. Morphological and structural analyses using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) confirmed the successful fabrication of a uniform nanocomposite architecture. Systematic optimization revealed that the sensor exhibited excellent detection performance for H 2 O 2 , with a sensitivity of 22.3 μA mM −1  cm −2 ( n  = 4), a detection limit as low as 59 nM (S/N = 3), a limit of quantification of 0.197 μM, and a linear range of 62 nM–13.07 mM, exhibiting good selectivity and reproducibility. Importantly, the sensor was successfully applied for the real-time, in-situ monitoring of H 2 O 2 released from zebrafish embryos under cadmium ion (Cd 2+ ) induced oxidative stress. This work offers a promising tool for the early assessment of heavy metal-induced oxidative damage.