Simultaneous detection of streptomycin and kanamycin based on an all-solid-state potentiometric aptasensor array with a dual-internal calibration system

A novel potentiometric aptasensor array based on a 4-channel screen-printed carbon electrode was developed with a dual-internal calibration system for the simultaneous detection of streptomycin and kanamycin. Two channels were used as working channels for assembling the aptamers of the two targets, and the other two channels acted as calibration channels. The calibration channels functioned by immobilizing two all-A sequences were employed to subtract the influence from the background matrix and further improve the detection accuracy. Consequently, under optimal conditions, this aptasensor array showed high sensitivity for the detection of streptomycin and kanamycin with detection limits of 9.66 pM and 5.24 pM, respectively, and corresponding linear response ranges of 10 pM-10 mu M and 10 pM-1 mu M, respectively. Moreover, it presented high specificity without mutual interference between the two targets or with other antibiotics and also demonstrated good repeatability. This aptasensor array was further applied to the simultaneous detection of streptomycin and kanamycin in real milk samples, and the results were validated by liquid chromatography-mass spectrometry (LC-MS). The results demonstrated satisfactory accuracy and precision and showed the great application potential of the aptasensor array with internal calibration for on-site detection of multiple targets.