Entropy spontaneous ratiometric electrochemical aptasensor based on polymerization and AuNPs signal amplification for Acetamiprid residue analysis

Acetamiprid (ACE), a next-generation chlorinated neonicotinoid insecticide, has been extensively employed for pest control. However, its excessive residues in food and the environment have raised significant concerns regarding human health. To address the need for a simple, accurate, and efficient ACE detection method, this study developed a ratiometric electrochemical aptasensor utilizing a dual signal amplification strategy involving atom transfer radical polymerization (ATRP) and gold nanoparticles (AuNPs). Methylene blue (MB) served as the internal reference signal, which was attached to the ACE aptamer-DNA ₁ (dsDNA) through electrostatic adsorption and intercalation. Ferrocenyl methyl methacrylate (FMMA) was polymerized into long chains via ATRP, generating a significantly amplified electrical signal compared to that of monomeric FMMA. AuNPs, known for their bioconjugability, were linked to DNA ₂ (AuNPs-DNA ₂ ), enhancing the DNA ₂ loading capacity and expanding the ATRP reaction sites. In the presence of ACE, the MB signal decreased while the FMMA polymer signal increased, achieving a ratiometric detection strategy with a limit of detection (LOD) of 19.26 pg/mL. This ratiometric aptasensor not only enhances selectivity but also mitigates the influence of background currents, offering a novel and effective approach for ACE detection in real-world sample analysis.