Electrochemiluminescence immunosensor for thiamethoxam detection using NiFe-LDH-loaded Cu single-atom catalysts

An ECL signal amplification strategy is introduced leveraging a multimetallic catalytic amplification effect. Nickel-iron bimetallic oxide compounds were synthesised and loaded with Cu SAs catalysts on their surface to create nickel-iron layered double hydroxides/copper single atoms (NiFe-LDHs/Cu-SAs) with robust catalytic properties. These NiFe-LDHs/Cu-SAs were employed as signal amplification elements to modify gold electrodes. C-dots labelled with thiacloprid DNA aptamers were used as the signal and molecular recognition elements to construct an electrochemiluminescence (ECL) immunosensor. The NiFe-LDHs/Cu-SAs significantly amplified the ECL signal of the C-dots, enhancing the sensitivity of the sensor. Upon capturing thiamethoxam via the aptamer, the ECL signal was effectively quenched, demonstrating the potential of this approach as a highly sensitive method for thiamethoxam detection. The excellent catalytic performance of NiFe-LDHs/Cu-SAs amplified the detection signal over 20-fold, while the aptamer improved the specificity of the sensor for thiamethoxam recognition. The method demonstrates a linear range of 2-6000 × 10^-12 mol/L and a detection limit of 6.52 × 10^-13 mol/L, with recoveries of 90%-110% for real sample analysis. This study demonstrates a highly sensitive and specific method for thiamethoxam detection, with real-world applicability, while highlighting an innovative multimetallic catalytic strategy that can facilitate advancements in sensor design across various fields.