Hierarchical MOF-on-MOF-structured dual-functional nanozyme for enhanced catalysis and the 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. Synergistic interactions between MOF components often yield emergent properties beyond those of individual frameworks. In this study, we develop an MOF-on-MOF nanozyme (CeM-ON-CuM), which combines the oxidase-like activity of CeMOF with the laccase-like activity of CuMOF for the dual-channel detection of the anti-diabetic enzyme α-glucosidase (α-Glu). 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 the detection of α-Glu via fluorescence at 585 nm. Meanwhile, phenol is released from phenol-α-D-glucopyranoside upon α-glucosidase activity, which is detected at 510 nm. CuMOF catalyzes phenol oxidation, and its coupling with 4-aminoantipyrine (4-AAP) generates red quinoneimine, which facilitates the colorimetric detection of α-Glu. The limits of detection were as low as 0.16 and 0.35 U L⁻¹ for colorimetric and fluorescence detection, respectively. The sensing method was further applied to the detection of α-Glu in human serum, proving its application in real-world samples and potential for bedside detection.