An exonuclease III-driven dual-mode aptasensor based on Au-Pd@Fc nanozyme and magnetic separation pretreatment for aminoglycoside antibiotics detection.

A novel dual-mode aptasensor was constructed for aminoglycoside antibiotics (AAs) detection by using a broad-spectrum aptamer as a biorecognition element, and Au-Pd@Fc functionalized by signal DNA as nanoprobes. In electrochemical mode, the target-induced cyclic amplification reaction run under the action of exonuclease-III, which increased the number of nanoprobes on the electrode surface. AAs could be quantitatively detected with LOD of 0.0355 ± 0.00613 nM. In colorimetric mode, the Au-Pd@Fc nanozyme catalyzed the color reaction of 3,3',5,5'-tetramethylbenzidine. The blue-shifted absorbance will be observed with the change of AAs concentration, and the LOD was 0.0458 ± 0.00572 nM. Furthermore, a magnetic molecular-imprinted material capable of specific adsorption of AAs was prepared on milk sample pretreatment. The aptasensor was used to detect 10 kinds of AAs in milk and the recoveries were 97.19 ± 4.41% ∼ 98.70 ± 4.45% and 96.38 ± 3.53%-97.54 ± 4.13% in electrochemical and colorimetric methods. This work provided a theoretical basis for the application of aptamers in simultaneous detection of antibiotics.