Laccase-mimicking enzyme with fluorescent properties for dual-mode detection of epinephrine and degradation of phenolic pollutants

Abstract

Despite considerable interest has been shown in research on nanozymes in recent times, the creation of highly active bifunctional nanozymes remains a significant challenge. Inspired by the structural features of the active center of natural laccase, bifunctional copper-based nanozymes (Cu-MB) possessing both laccase-like activity and fluorescence properties using 2-methylimidazole (2-MI) and 2-aminoterephthalic acid (BDC-NH₂) as ligands have been prepared. The K_m of Cu-MB was 0.0898 mM, which was markedly lower than that of previously reported nanozymes and natural laccase. A dual-mode sensor for the detection of epinephrine (EP) was designed based on the high catalytic activity, excellent fluorescence properties, and stability of Cu-MB nanozymes. The limits of detection (LODs) of the colorimetric and fluorescence sensors for EP were 0.22 µg/mL and 0.11 µg/mL, respectively. The sensor system was verified to have good resistance to interferences and reliability by analyzing actual samples. Furthermore, the integration of a dual-reading hydrogel with a smartphone facilitates the portable, real-time, and rapid assessment of EP. More encouragingly, Cu-MB has excellent substrate versatility and can effectively degrade a diverse array of phenolic pollutants. The developed Cu-MB nanozymes provide a promising approach for the degradation and determination of phenolic compounds. Clinical trial number: not applicable.

Graphical abstract