Facilely fabricating triple-atom Fe/Zn/Ir luminescent nanozymes with peroxidase-like activity for dual mode melatonin detection

Herein, a novel ternary-atomic Fe/Zn/Ir nanozyme (Fe/Zn/Ir TAzyme) with peroxidase (POD)-like and luminescence properties is fabricated through coordinating Ir(III) complex into the as-prepared Fe/ZIF-8. The preparation procedures avoid high-temperature and pyrolysis which endue Fe/Zn/Ir nanocomposite with high stability and can be scaled up. Once Fe/Zn/Ir TAzyme catalyzes the substrate TMB to produce blue oxidized TMB (oxTMB), its luminescence is quenched by the generated oxTMB. Ascribed to its high POD-like activity and interesting luminescence property, a dual-mode sensing platform for the detection of melatonin (MT) is fabricated. In the presence of increasing concentrations of MT, the absorbance of the detection system declines, while the emission of the detection system grows. The detection platform exhibits the limits of detection (LODs) in colorimetric and luminescence detections are 8.9 nM and 8.8 nM, respectively, which can mutually validate the assay results. More importantly, Fe/Zn/Ir TAzyme has been fabricated into test swabs to monitor MT in the way of portable and naked-eye detection. This double-role TAzyme provides new conceptions for researchers to explore novel and highly efficient nanozymes in future.