Magnetic MXene-based molecularly imprinted electrochemical sensor for methylmalonic acid

A novel magnetic Ti₃C₂T_x-MXene/Fe₃O₄ composite was prepared from Ti₃C₂T_x and magnetic Fe₃O₄. The characterizations by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) exhibited that the Ti₃C₂T_x/Fe₃O₄ nanomaterial presented an outstanding conductivity and a large specific area, which could improve the electron transfer rate, leading to the amplification of the sensor's signal. Furthermore, an ultrasensitive molecularly imprinted electrochemical sensor based on MXene/Fe₃O₄ composites was fabricated for detecting methylmalonic acid (MMA) with high selectivity. The current intensity of differential pulse voltammetry of the sensor presented a good linear relationship with the logarithm of MMA concentration ranging from 9 × 10^-15 mol L^-1 to 9 × 10^-13 mol L^-1. The detection limit of the sensor was 2.33 × 10^-16 mol L^-1. The fabricated sensor was utilized for detecting MMA in human serum samples with excellent recoveries. Therefore, this method significantly improved the sensitivity of detection, and constitutes an  affordable sensing platform for trace detection of organic carboxylic acid.