Ultrasensitive and selective nanomolar detection of quercetin in 12 complex food matrices via 3D hierarchical SiO₂@MoS₂/MXenes heterostructured sensor

Quercetin (Que) is a ubiquitous flavonoid and polyphenol antioxidant. Negatively charged MoS₂ was self-assembled onto the surface of positively charged SiO₂ nanospheres to form SiO₂@MoS₂ core-shell materials. Subsequently, the materials were embedded into the interlayer of MXenes to form an effectively conductive three-dimensional heterostructured composite. The MoS₂ shell formed on SiO₂ not only retained the intrinsic properties of SiO₂ but also improved its conductivity and specific surface area. In addition, the addition of SiO₂@MoS₂ to the interlayer of MXenes effectively alleviated the interference within the potential window and promoted the accurate electrical signal detection of Que. The detection range of the SiO₂@MoS₂/MXenes electrochemical sensor was 20 nM ∼ 30 μM, and the detection limit was 2 nM. The sensor can be effectively applied to the detection of Que. in 12 kinds of fruits, vegetables and agricultural products, and the results were comparable to those of UV spectrophotometry with satisfactory recovery.