A novel dual-ligand copper-based nanoflower for the colorimetric and fluorescence detection of 2,4-dichlorophenol, epinephrine and hydrogen peroxide

Background: Nanozymes have the advantages of cost effective, simple synthesis, high durability and stability, and have been widely used in various fields. However, only a few nanomaterials with multiple enzyme-like activity have been reported, and most of the currently developed nanozymes are usually used in colorimetric or fluorescence analysis depending on a single colorimetric or fluorescence signal output. In this study, a copper-based dual-ligand biomimetic nanoflower (Cu-MN) was constructed, which demonstrated potential multiple enzymelike activity, and was applied to the multi-mode detection of 2,4-dichlorophenol (2,4-DP), epinephrine (EP), and H2O2. Results: The laccase-like activity of Cu-MN can catalyze the conversion of 2,4-DP and EP, resulting in the formation of red and yellow-brown oxidation products with distinct UV absorption peaks at 510 nm and 485 nm, respectively. Furthermore, the fluorescence emission peak at 426 nm of Cu-MN can be dynamic quenched during substrate oxidation due to the fluorescence internal filtration effect (IFE). Therefore, a dual-mode analysis method was constructed to detect 2,4-DP and EP by fluorescence and ultraviolet colorimetry, which was successfully applied in natural lake water and rabbit plasma analysis, respectively. Furthermore, a colorimetric sensing strategy based on the peroxidase-like activity of Cu-MN was developed and successfully applied to the monitoring of H2O2 in hydrogen peroxide disinfectant. Additionally, the visualization analysis method was also established by RGB reading of the smartphone. Significance and novelty: In brief, inspired by the fluorescence characteristics of 2-aminoterephthallc acid and the imidazole group of 2-methylimidazole, a novel copper-based dual-ligand biomimetic nanoflower (Cu-MN) was prepared and used to establish multi-mode method for the detection of 2,4-DP, EP, and H2O2, which opens up new avenues for its applications in bioanalysis and environmental monitoring.