Energy-Transfer-Based Dual-Mode PEC-ECL Biosensor for Acetamiprid Analysis Sensitized by Two-Step DNA Circuit...

Sensitive and accurate determination of acetamiprid is highly desirable for guaranteeing food safety. In this Letter, an energy-transfer-based dual-mode biosensor was developed using zinc-based metal-organic frameworks (Zn-MOFs) acting as both photoelectrochemical (PEC) and electrochemiluminescent (ECL) donors and Pt@Cu₂O cubic nanocrystals (CNs) as the energy acceptor for detecting acetamiprid. By integration of aptamer recognition with two-step DNA circuit amplification (entropy-driven DNA cycle and DNA walker), the detection of acetamiprid was converted into the assay of abundant intermediate DNA strands. With the help of nicking endonuclease, a large number of single-stranded DNAs was generated on the surface of Zn-MOFs, which were used as multifunctional PEC and ECL substrates. Through competitive hybridization, Pt@Cu₂O CNs as broad-spectrum quenchers were introduced, thereby enabling changes in the PEC and ECL responses for acetamiprid quantitation. The experimental results proved that the combination of energy transfer, two-step DNA circuit amplification, and dual-mode sensing strategy achieved the sensitive and accurate analysis of acetamiprid, with low detection limits of 20.2 fM (PEC mode) and 17.5 fM (ECL mode) within a wide range from 0 to 1 × 10^-9 M. The excellent specificity, reproducibility, and practicality confirmed the potential application of the biosensor for pesticide-related food safety.