Multivalent SnO₂ quantum dot-decorated Ti₃C₂ MXene for highly sensitive electrochemical detection of Sudan I in food

Quantum dots functionalization has been proven to be a simple modification strategy for improving the electroanalytical performance of two-dimensional electrode materials by increasing the specific surface area and active reaction sites. Herein, a new electrochemical sensing platform was fabricated by SnO₂ quantum dot-functionalized Ti₃C₂ MXene (Ti₃C₂-SnO₂QDs) for the highly sensitive detection of Sudan I in food. Ti₃C₂-SnO₂QDs were prepared via in situ synthesis, which can control the nucleation and growth of SnO₂QDs, resulting in the well-dispersed SnO₂QDs with 2-3 nm size on the intersheet surface of MXene. Moreover, the formation of Ti₃C₂-SnO₂QDs can effectively restrict the aggregation of Ti₃C₂ and improve the stability of SnO₂QDs in aquatic environment. The prepared nanocomposite can be used as an improved modified material to further increase the electrocatalytic performance and electrochemical signal of Sudan I on the surface of a glassy carbon electrode. Under optimized conditions, the proposed analytical method displayed a linear dependence for Sudan I concentration ranging from 0.008 to 10 μM with a detection limit of 0.27 nM (S/N = 3) by electrochemical cyclic voltammetry. This sensor with excellent selectivity, reproducibility and accuracy was quantitatively validated in commercial ketchup and chili powder. This Ti₃C₂-SnO₂QDs-based Sudan I sensor is expected to expand the application of MXene nanocomposites in electrochemical analysis and is envisioned as a promising candidate for monitoring illegal food additives in real food samples.