Hierarchical MOF-on-MOF Structured Dual-Functional Nanozyme for Enhanced Catalysis and Dual-Channel Detection of α-Glucosidase

Abstract

Metal-organic framework (MOF)-on-MOF hybrids have garnered significant interest due to their ability to integrate multiple catalytic functions within a single nanostructure. The synergistic interactions between MOF components often yield emergent properties beyond those of individual frameworks. In this study, we develop a MOF-on-MOF nanozyme (CeM-ON-CuM) combining the oxidase-like activity of CeMOF with the laccase-like activity of CuMOF for dual-channel detection of the anti-diabetic enzyme α-glucosidase (α-Glu). Specifically, we construct a MOF-on-MOF hybrid by integrating the laccase-like activity of CuMOF and the oxidase-like activity of CeMOF. CeMOF catalyzes the oxidation of Ampliflu Red (AR) to fluorescent oxAR, while α-glucosidase hydrolyzes ascorbyl glucoside (AAG) to ascorbic acid (AA), which inhibits this oxidation, enabling detection via fluorescence at 585 nm. Meanwhile, phenol is released from phenol-α-D-glucopyranoside upon α-glucosidase activity and detected at 510 nm. CuMOF catalyzes phenol oxidation and its coupling with 4-aminoantipyrine (4-AAP) to generate red quinoneimine, which facilitates the colorimetric detection for α-Glu. The limits of detection were as low as 0.16 and 0.35 U/L, respectively. The sensing method was further applied to the detection in human serum, proving the application in real sample, exhibited potential for the bedside detection.