A molecularly imprinted sensor based on Cu2O mimic enzyme for spectroscopic and colorimetric dual-mode detection of doxycycline

A molecularly imprinted sensor is smartly designed by using Cu 2 O as the core and SiO 2 as the imprinting layer, which can be used for the detection of doxycycline (Dox). As a peroxidase mimic, Cu 2 O can catalyze colorless o -phenylenediamine (oPD) to yellow 2,3-diaminophenazine (DAP), however, the peroxidase-like activity of the Cu 2 O core is shielded after Dox is rebound to the molecularly imprinted SiO 2 (MI-SiO 2 ). As the absorbance of DAP at 416 nm ( A 416 ) is linearly related to the concentration of Dox, spectroscopic detection of Dox can be achieved. The linear range is 0.1–10 μM, and the limit of detection (LOD) is 0.046 μM. In addition, a multicolor sensing strategy is also proposed by using the smartphone-based color recognition software. The ratio of green (G) value to blue (B) value is linearly related to the concentration of Dox, and thus colorimetric detection of Dox is achieved by the RGB color analysis. The linear range is 0.1–10 μM, and the LOD is 0.074 μM. Finally, dual-mode detection of Dox in lake water and honey is achieved with the developed molecularly imprinted sensor.