Development of ATP-modified CoFe₂O₄@ZIF-8@ZIF-67 core–shell nanozyme for sensitive colorimetric detection of dopamine

Core-shell nanostructures (NSs) are a type of nanozyme broadly used in various fields due to their significant physicochemical advantages. In the present study, the CoFe₂O₄@ZIF-8@ZIF-67 core–shell were fabricated by a consecutive two-step synthesis method, including hydrothermal for CoFe₂O₄ metal spinel and epitaxial solvothermal growth of ZIFs bilayers on the metal spinel NSs. The core–shell surface was modified using ATP inspired by the active site of the natural peroxidase enzyme. The nanocomposites were characterized by XRD, FT-IR, SEM, EDX, and Dot-mapping techniques. The peroxidase-like activity of the ATP/CoFe₂O₄@ZIF-8@ZIF-67 was assessed by a colorimetric method. Modified nanocomposite displayed desirable peroxidase mimetic activity and could enzymatically generate hydroxyl radicals from H₂O₂ and oxidize TMB. The high catalytic activity of ATP-modified nanocomposite and its ability to oxidize TMB provides a rapid and sensitive platform for the colorimetric detection of dopamine. Dopamine consumes hydroxyl radicals, prevents TMB oxidation, and causes a color change in the detection solution, which the naked eye can recognize. The presented colorimetric test provided an excellent LOD for dopamine (0.4 µM) with a good linear range (0.2–18 µM) and selectivity, which was prosperously applied to dopamine assay in serum blood samples.