Colorimetric Detection of Kanamycin Residue in Foods Based on the Aptamer-Enhanced Peroxidase-Mimicking Activity of Layered WS2 Nanosheets

Although the colorimetric methods can easily meet the demands of point-of-care and ease-of-use for antibiotic detection, they still face many challenges in the accuracy and stability of assay. Herein, a facile and stable colorimetric aptasensor is first developed for kanamycin residue detection based on the aptamer-enhanced peroxidase-mimicking activity of layered WS₂ nanosheets. The investigation confirmed that aptamer sequences can improve the affinity of nanosheets to the chromogenic substrate 3,3'',5,5''-tetramethylbenzidine, resulting in a significant increase of the peroxidase-mimicking activity. Under the optimal conditions, the limit of detection of the proposed colorimetric aptasensor for kanamycin was determined to be as low as 0.6 μM, and such an aptasensor displays excellent selectivity against other competitive antibiotics. Moreover, further studies have verified the applicability of the established colorimetric aptasensor in several actual samples, indicating that the aptasensor may have bright application prospects for kanamycin detection in livestock husbandry and agriculture samples.