Highly sensitive detection of luteolin with AuNPs-MXene functionalized electrochemical sensing platform

The sensitive detection of luteolin is crucial for monitoring its levels in botanical sources, assessing its clinical pharmacokinetics, and guaranteeing the efficacy of luteolin-containing products. In this study, a high-performance electrochemical sensing platform for luteolin detection was developed based on a gold nanoparticle (AuNPs)/Ti₃C₂T_x-MXene composite. Ti₃C₂T_x-MXene was first etched from the Ti₃AlC₂-MAX phase using hydrofluoric acid and further functionalized with polyethylenimine to endow it with a positive surface charge. This modification facilitated the electrostatic self-assembly of negatively charged AuNPs onto the MXene surface, forming a stable AuNPs-MXene composite with enhanced electrical conductivity and a large effective surface area. The electrochemical behavior of luteolin at the AuNPs-MXene-modified glassy carbon electrode was systematically investigated. Cyclic voltammetry and density functional theory calculations confirmed an adsorption-controlled, reversible redox process involving two electrons and two protons at the catechol hydroxyl groups of luteolin. Molecular electrostatic potential maps and highest occupied molecular orbital distribution further verified the catechol hydroxyls as the primary redox-active sites. Under optimal conditions, the sensor displayed a wide linear response range from 1.0 × 10^-4 μM to 100 μM and a low detection limit of 0.034 nM, outperforming most previously reported electrochemical sensors for luteolin. Its practical application was validated by determining luteolin in commercial Duyiwei capsules and chrysanthemum samples via the standard addition method. This work not only offers a reliable tool for luteolin detection but also extends the application of MXene-based composites in the electrochemical sensing of flavonoids.