Second generation of signaling-probe displacement electrochemical aptasensor for detection of picomolar ampicillin and sulfadimethoxine

Abstract

The high-throughput sensors suitable for both hydrophilic and lipophilic targets are highly desired for environmental pollutants including antibiotics. Previously we reported a signaling-probe displacement electrochemical aptasensor (SD-EAS) that achieved excellent performance for the detection of kanamycin A, but failed the detections of lipophilic antibiotics including ampicillin (Ampi) and sulfadimethoxine (SDM). In this report we solved the generality problem and developed the second generation of SD-EAS (SD-EAS II) by optimizing the surface chemistry. SD-EAS II with HS-(CH2)2-[OCH2CH2]6-OCH3 passivation self-assembled monolayer enabled the detection of Ampi and SDM all with the unprecedented detection of limit (LOD) (3S/N: 10pM and 1nM), broad dynamic range (100pM–1mM and 1 nM–1mM), and high selectivity (>100 and 10000 fold). The practical applications were demonstrated by the detection of Ampi/SDM spiked-in lake water with a LOD of 0.28 and 7nM, respectively, showing the good anti-inference capability of SD-EAS II. This work represents the first study of the effect of surface chemistry on the performance of EAS for the detection of lipophilic targets and lays the ground work for the future development of high-throughput EAS chips.