Multiplex electrochemical aptasensor for detecting multiple antibiotics residues based on carbon fiber and mesoporous carbon-gold nanoparticles

We proposed a multiplex electrochemical aptasensor based on a screen-printed carbon electrode (SPCE), which was modified by carbon nanofibers (CNFs) and mesoporous carbon-gold nanoparticles (OMC-AuNPs) for the ultrasensitive detection of kanamycin (KAN) and streptomycin (STR). The designed aptasensor had some characteristics of a high electrochemical conductivity and a high specific surface area because of rod-like OMC-AuNPs and CNFs. Moreover, CNFs and OMC-AuNPs could be homogeneously and firmly adhered to the surface of SPCE, and complimentary strands of aptamers could also be well immobilized on the surface of the electrode modified with CNFs and OMC-AuNPs. In the absence of KAN and STR, the aptamers bound to their complimentary strands. Upon addition of KAN and STR, the aptamers bound to their targets, which led to the complementary strands released from the aptamers and more changes of current peaks because of the aptamers labelled with CdS and PbS. Under the optimal conditions, this aptasensor showed a high stability and a selectivity toward KAN and STR with limits of detection (LODs) as low as 87.3 and 45.0 pM, respectively. The applicability of the developed aptasensor was successfully assessed by detection of KAN and STR in a spiked milk sample without any interference from the sample matrix. It is expected that the proposed aptasensor can be easily detect residues of other antibiotics in milk by replacing different aptamers.