Spatial confinement-accelerated catalytic hairpin assembly on a Y-shaped DNA nanoscaffold for ultrasensitive detection of aflatoxin B1.

The sensitive detection of aflatoxin B1 (AFB1) is crucial for food safety monitoring. However, conventional catalytic hairpin assembly (CHA) amplification strategies fundamentally constrained by diffusion-limited kinetics due to reliance on free diffusion. To address this limitation, we developed a spatial confinement-accelerated catalytic hairpin assembly (SCA-CHA) strategy. The target AFB1 initiates the formation of the Y-shaped scaffold, which spatially co-localizes the CHA reactants (two hairpins and one catalyst) at its three termini. This confinement drastically elevates the local effective concentration by over 5000-fold, thereby overcoming the diffusion barrier and accelerating the reaction kinetics. Furthermore, its successful application in complex food matrices (maize, red wine, milk) yielded satisfactory recoveries from 91.5% to 107.8%, underscoring its great potential for rapid and reliable on-site screening of food contaminants.