Ultraselective antibiotic sensing with complementary strand DNA assisted aptamer/MoS2 field-effect transistors

Although aptamer has been demonstrated as an important probe for antibiotic determination, the selective sensing of different antibiotics is still a challenge due to their structure similarities and wide folding degrees of aptamer. Herein, a field-effect transistor using MoS 2 nanosheet as the channel and an aptamer DNA (APT) with its configuration shaped by a complementary strand DNA (CS) is employed for kanamycin (KAN) determination. This probe structure contributes to an enhanced selectivity and reliability with reduced device-to-device variations. This MoS 2 /APT/CS sensor shows time-dependent performance in antibiotic sensing. Prolonged detection time (20 s–300 s) leads to an enhanced sensitivity (1.85–4.43 M -1 ) and a lower limit of detection (1.06–0.66 nM), while a shorter detection time leads to a broader linear working range. A new sensing mechanism relying on charge release from probe is proposed, which is based on the “replacement reaction” between KAN and APT-CS. This sensor exhibits an extremely high selectivity (selectivity coefficient of 12.8) to kanamycin over other antibiotics including streptomycin , tobramycin , amoxicillin , ciprofloxacin and chloramphenicol . This work demonstrates the merits of probe engineering in label-free antibiotic detection with FET sensor, which presents significant promises in sensitive and selective chemical and biological sensing.