Magnetic DNA walker-engineered electrochemical sensor for highly sensitive detection of antibiotics

Antibiotics residue pollution in food and environmental matrices has posed a serious threat to global public health. It is an urgent demand in developing highly sensitive methods for the detection of low-abundance antibiotics in real samples. Herein, we established a magnetic DNA walker-engineered electrochemical sensor by taking advantages of the distinct recognition capability of aptamer and the excellent signal amplification performance of magnetic DNA walker for the accurate detection of kanamycin (Kana). The aptamer can specifically recognize Kana, while the magnetic DNA walker can not only amplify the target signal through the cascade displacement reaction, but also effectively reduce background interference via the magnetic separation, thus ensuring the sensitivity and accuracy of Kana detection in complex samples. The proposed electrochemical sensing method possesses a good linear relationship in the range of 10 fM −1 μM, and the limit of detection is as low as 0.02 fM. Moreover, the excellent selectivity allows this sensor has the ability to specifically identify the Kana from other antibiotics and even in the milk and tap water.