An Electrochemical Aptamer-Based (E-AB) Sensor Using Ti₃C₂T_x(MXene) and cDNA-PAA for Detection of AFB1

An electrochemical aptasensor based on Ti₃C₂T_x (MXene) and cDNA-PAA was established for sensitive detection of aflatoxin B1 (AFB1) in peanuts. The high specific surface area of Ti₃C₂T_x (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^-3 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).