Ion-imprinting strategy towards a novel two-in-one copper-based nanozyme for sensitive electrochemical-colorimetric dual-mode detection of paracetamol

Dual-mode sensors integrating multifunctional nanozymes are highly sought by the analytical chemistry community. However, rational design of nanozymes containing both metal single atoms (SAs) and atomic clusters (ACs) for dual-mode sensing remains a challenge. Herein, we designed and synthesized a novel Cu-based nanozyme system based on Cu SAs/ACs anchored on a N-doped chitosan-derived carbon support (CuSAs/ACs@NC) using a tandem ion imprinting-pyrolysis-etching strategy. Compared with Cu SAs or Cu nanoparticles on the chitosan-derived carbon support, the proposed CuSAs/ACs@NC nanozyme exhibits superior electrocatalytic activity and peroxidase-mimicking activity. Benefitting from the synergistic effect of Cu SAs and ACs which enhances electron transport, the CuSAs/ACs@NC nanozyme allows electrochemical-colorimetric dual-mode detection of paracetamol (PA) based on the amplification of the electrochemical signal of PA and the inhibition effect of PA on peroxidase activity, respectively. The linear range of the electrochemical mode is 2.00-473.00 μM with a detection limit of 0.48 μM, while that of the colorimetric mode is 0.25-100.00 μM with a detection limit of 0.10 μM. Moreover, this dual-mode sensor exhibits favorable reproducibility (relative standard deviation ≤ 4.00 %), stability (maintaining stable after 4 months of storage), and accuracy (recoveries of 91.5-114.9 %). Satisfyingly, the developed dual-mode method allows accurate PA detection in commercial drugs with relative deviation below 1.5 %. This work presents a new strategy for the preparation of SAs/ACs as multifunctional nanozymes for sensing, drug monitoring, and clinical diagnosis.