Cu-MoO_x-based nanozyme with enhanced peroxidase like activity for quinolone antibiotics detection

The abuse of antibiotics has seriously threatened human health and living environment. Nevertheless, the detection of quinolones is currently mainly performed by high-cost and cumbersome means, such as High-Performance Liquid Chromatography (HPLC). Herein, we reported a novel method based on copper-doped MoO_x nanoparticles (Cu-MoO_x NPs) with peroxidase-like enhancement activity for the easy preparation, sensitive and rapid visualization of quinolone detection. Cu-MoO_x NPs can make the chromogenic substrate 3,3',5,5'-Tetramethylbenzidine (TMB) change from colorless to blue. Moreover, the addition of quantitative quinolone antibiotics can significantly accelerate the TMB oxidation reaction. Based on this phenomenon, a colorimetric method for detecting quinolone antibiotics was established with a good linear relationship ranging from 1 × 10^-6 M to 1.3 × 10^-4 M, and the detection limit was 0.310 μM for ciprofloxacin (CIP) and 0.520 μM for levofloxacin (LVFX). Furthermore, the mechanism was also explored, and the results showed that the peroxidase-like activity of Cu-MoO_x NPs was probably derived from the generated OH, ¹O₂, oxygen vacancies and partially reduced Cu⁺, and on the other hand was derived from quinolone antibiotics and nanozymes electrostatic interaction between them.