Designing an electrochemical aptasensor based on immobilization of the aptamer onto nanocomposite for detection of the streptomycin antibiotic

Streptomycin (STR), an aminoglycoside antibiotic, was used in human and veterinary to treat gram-negative infections. STR residue causes serious side effects on human health. Accordingly, to achieve a novel and sensitive method for detection of STR, we attempted to develop electrochemical sensing system based on graphene quantum dots (GQDs) functionalized with amine (NH) and thiol (SH) groups (GQDs-N-S) as the promising newest carbon-based nanomaterial. In this sensing system, gold nanoparticle (AuNPs) was deposited on the GCE surface. Then GQDs-N-S was coated on the AuNPs/GCE surface. After, the silver nanoparticle (AgNPs) coated on the GQDs-N-S/AuNPs/GCE. Finally, the STR thiol-aptamer (SH-Apt) was covalently attached on the AgNPs/GQDs-N-S/AuNPs/GCE via bonding formation of AgS. This system showed linear range from 0.01 pg·mL−1 to 812.21 pg·mL−1 with limit of detection of 0.0033 pg·mL−1; it was as good as or better than other similar assays, and also the proposed system, in the presence of different interferences, displayed good selectivity in detecting STR. The proposed aptasensor showed excellent results in quantitatively the detection of STR in serum samples.