Platinum/palladium-enhanced Cu-Cu2O nanozyme grown on manganese sheet for efficient peroxidase-like catalysis and sensitive colorimetric ampicillin detection

A novel Cu-Cu 2 O/MnPtPd composite with enhanced peroxidase-like activity was synthesized and evaluated for colorimetric ampicillin (AMP) detection. The composite was prepared through in situ growth of Cu 2 O on a Mn-based substrate, followed by Pt and Pd nanoparticle incorporation to synergistically modulate its structural and electronic properties. This design markedly improved the catalytic decomposition of H 2 O 2 and the subsequent oxidation of 3,3′,5,5′-tetramethylbenzidine. The Cu + /Cu 2+ redox cycle dominates the catalytic process, while the synergistic interactions among Cu, Mn, Pt, and Pd promote H 2 O 2 activation to generate •O 2 − , identified as the primary reactive species driving the colorimetric reaction. Steady-state kinetics demonstrated high affinity and catalytic efficiency toward both H 2 O 2 and TMB, surpassing natural horseradish peroxidase. Based on this nanozyme, an enzyme-free colorimetric sensing platform for AMP was established, which exhibits a dual linear response in both low concentration range (0.05–100 μg/mL) and high concentration range (100–300 μg/mL), with a low detection limit of 14.5 ng/mL. The sensor showed excellent selectivity and anti-interference capability. Recoveries for AMP in real water samples ranged from 96.34% to 103.3% with RSD below 4.31%. These results demonstrate that the Cu-Cu 2 O/MnPtPd nanozyme provides a stable, low-cost, and high-performance alternative for non-enzymatic AMP detection in environmental and food monitoring.