A Nb.BbvCI-mediated electrochemical aptasensor using tetrahedral DNA nanostructures for the repetitive detection of...

Enhancing the regenerative utilization efficiency of electrochemical sensors has long been a challenge. To address this issue, we fabricated a renewable citrinin (CIT) electrochemical aptasensor based on tetrahedral DNA nanostructures (TDN). The signal probe was anchored to the TDN framework through Hoogsteen base pairing, forming a parallel triple-helical ('triplex') structure. The sensor reset regeneratively by pH adjustment, which controlled third-chain binding via parallel triplex pH-dependence. To increase the sensitivity of the sensor, we introduced a DNA walking system that released a significant amount of guanine-rich single-stranded fragments (G30) with the assistance of the nicking endonuclease Nb.BbvCI Nicking Endonuclease (Nb.BbvCI). Signal probes were prepared by the specific adsorption of methylene blue (MB) and unbound guanine bases (G), forming a signal amplification strategy. Under optimal conditions, the constructed renewable aptasensor exhibited excellent detection performance with a limit of detection of 5.96 × 10^-5 ng·mL^-1. The detection results remained stable over five regeneration cycles without any significant decrease in response current. Due to its high sensitivity and cost-effectiveness, the constructed sensor offers a facile strategy for the on-site detection of various targets.