An Electrochemical Aptamer-Based (E-AB) Sensor Using TiCT(MXene) and cDNA-PAA for Detection of AFB1.

An electrochemical aptasensor based on TiCT (MXene) and cDNA-PAA was established for sensitive detection of aflatoxin B1 (AFB1) in peanuts. The high specific surface area of TiCT (MXene) contributed to improve electrochemical efficiency and enhancing sensor stability which were characterized by the Randles-Sevcik equation. The self-made polyacrylic acid (PAA) nanogel was added with aptamer complementary chain (cDNA) to form cDNA-PAA nano gel composite, which could realize the synergistic amplification of the difference between the electrochemical signals before and after the addition of AFB1. The sensing effect of cDNA-PAA was validated using DPV. Methylene blue (MB) was modified at the proximal 3' termini of the aptamer (Apt-MB), meanwhile AuNPs was used to immobilize Apt-MB and improve the efficiency of electrochemical reactions. The competition between AFB1 and cDNA-PAA combined with Apt MB resulted in a significant change in the electrochemical signal current. In addition, the constructed electrochemical aptasensor had a lower detection limit of 1.0 × 10 ng/L for AFB1 under optimal detection conditions, and a detection range of 1 to 1000 ng/L. Moreover, peanuts with different concentrations of AFB1 were used as actual detection samples. Through the constructed sensor detection, the spiked recovery rates within the spiking range of 50 to 500 ng/mL were 97.76% to 101.84% (n = 3).