Truncated affinity-improved aptamer for selective and sensitive detection of streptomycin in dairy products with label-free electrochemical aptasensor

The overuse of streptomycin (STR) can result in their residues in food, posing serious side effects on human health. This work aims to develop a novel and accurate electrochemical aptasensor for the detection of STR in dairy products. Owing to the interaction of a portion of the aptamer with its target, we have rationally truncated an already existing 79-mer STR aptamer sequence, obtaining a smaller size, lower synthesis cost, and higher affinity truncated aptamer (S03 aptamer). The favorable affinity of S03 aptamer to STR was further verified. Then, an electrochemical aptasensor was established using S03 as a recognition molecule and polyaniline@N-doping carbon nanotube/Au nanoparticles (PANI@N-CNTs/AuNPs) as support matrix for the detection of STR. The detection limit of the S03 aptamer was lower than that of the full-length. It is preliminary proved that S03 truncated aptamer can be used as a recognition element for STR detection.