One-step cascade amplification system based on entropy-driven catalysis and DNAzyme triggered DNA walker for label-free detection of acetamiprid

Herein, an electrochemical aptasensor for highly sensitive detection of acetamiprid (ACE) was constructed based on a one-step cascade amplification strategy. This innovative strategy integrated DNA walker containing DNAzyme sequence into entropy-driven catalysis (EDC) system. The trigger strand was released by aptamer-specific binding to ACE, initiating the EDC amplification circuit and delivering DNA walker strands. The dangling DNA walker continuously bound and cleaved hairpin substrate to form G-quadruplex fragments with the assistance of Mg²⁺. The G-quadruplex fragments folded and captured hemin to form multitudinous G-quadruplex/hemin complexes in the presence of K⁺, generating significantly enhanced current, enabling enzyme-free, label-free and highly sensitive detection of ACE, with a linear detection range of 100 fM to 50 nM and a detection limit of 68.36 fM (S/N = 3). The constructed aptasensor achieved the reliable detection of ACE in vegetable soil and cucumber samples, demonstrating its potential application prospects in environmental protection and food supervision.