图二文字：MB-rp (1 m M), sDNA (1 m M), and OTA aptamer (APT) (1 m M) were
annealed together at 90 ℃ for 5 min, followed by decreasing
gradually to room temperature to form stable hybrid structures
(sDNA/MB-rP/APT) as the ratiometric probe. The gold electrode
(GE) was polished to obtain a mirror surface using 0.3 and 0.05 m m
alumina powder in order and then the electrode was ultrasonic
cleaned byethanol and deionized water, respectively. Afterthat, the
electrode was electrochemically cleaned in H 2 SO 4 (0.5 M) by CV
scanning in the potential range of 0.2e1.6 V until a stable voltam-
metric peak obtained. Then drop sDNA/MB-rP/APT mix solution
(10 m L) on the surface of electrode for 1 h to form the sDNA/MB-rP/
APT/GE through the AueS interaction, and then the modified
electrode was immersed in MCH (1 mM) solution for 1h at room
temperature to block the unoccupied sites.
