Neocuproine boosting catalytic activity of copper-based metal-organic frameworks for sensitive colorimetric...

Metal-organic frameworks (MOFs) nanozymes represent promising alternatives to natural enzymes, but their catalytic activity and efficiency remain insufficient for practical immunosensing applications. Herein, a neocuproine (Nc)-boosted Cu-MOFs catalytic activity strategy was proposed and applied to develop a rapid and efficient colorimetric immunosensor. Upon Nc assistance, the multi-hydrolase-mimicking catalytic capacities of Cu-MOFs were enhanced by 2.8- to 23.6-fold. Concurrently, the reductant generated during substrate hydrolysis triggered in situ reduction of Cu(II) to Cu(I), yielding a highly colored Cu(I)-Nc chelate for colorimetric analysis. The underlying mechanism of this cascade reaction was systematically explored. As a proof-of-concept, alpha-fetoprotein (AFP) was used to validate the feasibility and practicality of the proposed immunosensor. The analytical performance was satisfactory, with a wide detection range of 5-100 ng/mL, a limit of detection (LOD) of 1.4 ng/mL and an assay time of 5 min. Furthermore, this sensor was successfully applied to the analysis of real serum samples. Notably, Cu-MOFs integrate catalytic substrate hydrolysis, signal amplification, and chromogenic output, enabling simple, rapid sensing. Additionally, the successful implementation of phenanthroline-assisted Cu-MOFs system provides new insights into nanozyme catalysis and clinical immunoassays.