Selection of broad-spectrum aptamer and its application in fabrication of aptasensor for detection of aminoglycoside antibiotics residues in milk

The multi-residues of aminoglycoside antibiotics (AAs) have been reported present in a food product. Taking the broad-spectrum aptamer as recognition element of sensors for simultaneous detection of the class of AAs is of great significance. In this paper, broad-spectrum ssDNA aptamers for AAs with high affinity and specificity were successfully selected by graphene oxide (GO)-SELEX with a group of targets. Further sequence analysis, the truncated aptamer (AAs 03-2) of only 49 nt was observed with higher affinity than original aptamer of 79 nt. The binding mechanism analysis was performed by circular dichroism and molecular docking simulations, which showed the folding structure of aptamer (AAs 03-2) provided binding pockets for AAs and could recognize AAs conserved structure. Subsequently, the affinity of aptamer (AAs 03-2) for other AAs with favorable binding ability was further verified. Finally, the aptamer (AAs 03-2) was used to fabricate electrochemical biosensor based on screen-printed carbon electrode modified by ordered mesoporous carbon for signal amplification. The aptasensor realized simultaneous analysis of AAs with limit of detection of 2.47 nM. Moreover, the proposed aptasensor was successfully applied to evaluate the residual level of AAs in milk, which provides a new method for multi-residues detection of antibiotics.