An ultrasensitive homogeneous electrochemical strategy for ochratoxin a sensing based on nanoscale PCN-224@MB@Apt

In this reasearch, a homogeneous electrochemical sensor based on PCN-224@MB@Apt was fabricated for the ultrasensitive determination of ochratoxin A (OTA). Firstly, nanoscale PCN-224 were synthesized as the nanocarrier to embed the signal probe of methylene blue (MB). Then, the OTA aptamer (Apt) was added and connected to PCN-224@MB via the Zr– O –P bond between Zr metal sites of PCN-224 and phosphate group of Apt as the biogate. When OTA exists, the Apt would preferentially bind with OTA and fall off from PCN-224@MB, leading to the release of MB and generation of differential pulse voltammetry (DPV) response. The DPV response of MB was linearly correlated with the amount of OTA. The optimized PCN-224@MB@Apt sensor showed outstanding detection performance towards OTA with a low detection limit of 2.6 × 10 −5  ng/mL (S/N = 3) and wide linear range (10 −4 -10 ng/mL). Meanwhile, the fabricated homogeneous electrochemical sensor exhibited splendid stability, reproducibility, and specificity. To assess the practical applicability, the PCN-224@MB@Apt sensor was applied to detect OTA in real corn samples and desirable recovery rates varying from 83.2 % to 109.6 % were obtained.