Iron-nickel alloy co-reaction accelerator-based electrochemiluminescence platform with non-linear HCR-CHA cascade...

As a widely used yet highly toxic non-selective herbicide, paraquat (PQ) requires rigorous monitoring in the areas of agricultural residue detection and food safety. These demands necessitate the development of ultra-sensitive analytical methods to mitigate risks posed by paraquat and similar toxic molecules, thereby advancing analytical techniques toward higher precision and lower detection limits.

Herein, we present a quantitative electrochemiluminescence (ECL) platform that uses an iron-nickel composite material (FNC) as an efficient co-reaction accelerator, significantly intensifying the initial ECL signal. Following a competitive immunoreaction that converts the target PQ into a nucleic acid initiator, a cascaded, nonlinear HCR-CHA amplification process is triggered, yielding a large number of DNA sequences. These products then activate the CRISPR/Cas12a system, inducing its cis- and trans-cleavage activities to cleave the designed H5-H6-DA substrate and single-stranded DNA. This process releases the ECL quencher DA, thereby restoring the ECL signal and generating a substantial signal-on response. Based on this strategically integrated system, this ultra-sensitive analytical platform achieves an extremely low PQ detection limit of 0.083 pg/mL, demonstrating the powerful synergy of the entire design and its exceptional analytical performance.

This work makes significant advances in the analysis of toxic small molecules by combining an efficient ECL co-reaction accelerator, nucleic acid amplification and an enzyme catalytic system in a synergistic way. This strategy can be easily extended to other biomarkers and small molecules, establishing novel pathways for analyzing toxic molecules, ensuring food safety, detecting environmental pollutants, and making clinical diagnoses, among other applications.