An aptamer cocktail-based electrochemical aptasensor for direct capture and rapid detection of tetracycline in honey

Herein, we immobilized an aptamer cocktail on the surface of gold screen-printed electrodes and developed an electrochemical aptasensor with high sensitivity and specificity for direct capture and rapid detection of tetracycline (TC) in honey. The aptamer cocktail was composed of a comparatively short aptamer (Apt40) and a comparatively long aptamer (Apt76), which had different base composition, different chain lengths, and different folded binding sites. Application of the aptamer cocktail contributed to good spatial arrangement of binding sites of the two aptamers and large contact area of the aptamers-functionalized electrodes with TC-containing honey samples. All of the binding sites of the two aptamers were well exposed to capture TC, and thus, the aptamer cocktail exhibited higher recognition ability towards the TC than the individual aptamer. The aptamer cocktail-based electrochemical aptasensor provided a limit of detection (LOD) of 0.0073 ng/mL and a linear working range of 0.01-1000 ng/mL, when detecting TC in honey. Moreover, the aptasensor provided high specificity and good recovery rates of 96.45-114.6%. This study not only provided a new rapid detection method for highly sensitive and specific detection of TC residues but also served as a reference for developing aptasensors towards other targets.