Electrostatic intercalation of NH2-CNTs in MXene for enhanced interfacial charge transfer and ultrasensitive nitrofurantoin detection

Detecting trace nitrofurantoin (NFT) residues in food and water is critical for public health, yet practical applications are constrained by the scarcity of highly sensitive sensing materials. Herein, an MXene/amino-functionalized carbon nanotubes (NH 2 -CNTs) hybrid composite was fabricated via a facile electrostatic self-assembly strategy for NFT sensing. In this design, the positively charged NH 2 -CNTs spontaneously assemble with negatively charged MXene nanosheets through strong electrostatic interactions, serving simultaneously as interlayer spacers to effectively prevent MXene restacking and as highly conductive bridges with excellent electrocatalytic activity. This synergistic assembly yields a three-dimensional interconnected conductive network, which endows the composite with significantly enhanced electron-transfer kinetics, enlarged electrochemically active surface area, and superior electrocatalytic activity, thereby enabling pronounced signal amplification. Consequently, the optimized sensor with a mass ratio of 5:1 delivered excellent analytical performance toward NFT, with an ultrahigh sensitivity of 22.11 μA μM −1 cm −2 , a linear detection range of 0.05–15 μM, and a detection limit of 17 nM. Moreover, the sensor was successfully applied to the quantitative determination of NFT in milk, environmental water and honey samples, affording recoveries of 94.7–107.5%. These findings provide a facile strategy to overcome MXene restacking and highlight the promising potential of this sensing platform for food safety and environmental monitoring. Download: Download high-res image (148KB) Download: Download full-size image