An electrochemiluminescence sensor based on Fe/Zn-BTC@C-dots sensitisation for thiamethoxam detection

The performance of an electrochemiluminescent reagent directly affects the performance of its corresponding electrochemiluminescent (ECL) sensor. In this study, Fe/Zn-benzene-1,3,5-tricarboxylic acid metal–organic framework@C-dots (Fe/Zn-BTC@C-dots), which consist of a nano-loaded carbon quantum dot material with an excellent luminescence performance, were synthesised for the first time. Subsequently, they were used to modify the surface of a glassy carbon electrode, and combined with a single-chain thiamethoxam DNA aptamer to construct a biosensor. A novel method for the detection of thiamethoxam was established based on control of the excellent luminescence signal of the Fe/Zn-BTC@C-dots by specific recognition of the aptamer by the target molecule (a signal switch). Upon capturing thiamethoxam, the electrochemical luminescence intensity of the sensor was quenched. The ability of Fe/Zn-BTC to effectively catalyse and amplify the electrochemical luminescence of the C-dots significantly improved the sensitivity of the sensor, while the specific recognition of the target by the aptamer imparted the sensor with an excellent selection ability. Such an advanced approach is promising for the detection of thiamethoxam, with a linear range of 5–5000 × 10−11 mol/L and a sensitivity of 9.81 × 10−12 mol/L being achieved. Moreover, the sensor exhibited recovery rates of 90.5–109.3% upon the detection of thiamethoxam in actual samples.