Enhancing DNA Translocation Performance and Conformational Changes in Quartz Nanopipettes by Ionic Liquid Modification

The low signal-to-noise ratio (SNR), short dwell time, and complex DNA folding conformations remain significant challenges in DNA translocation sensors. This study utilized ionic liquid (IL) modification to enhance the DNA translocation performance and conformational changes. Initially, the impact of various types of ILs on ion current behavior and λ-DNA translocation was investigated. The results indicate that [Bmim][N(CN)2] is optimal due to its stable baseline current and significant translocation signal. Subsequently, different concentrations of ILs, modification durations, and nanopore sizes were examined to optimize the nanopore sensing conditions. Meanwhile, the ion current rectification phenomenon was analyzed using a finite element simulation. Furthermore, DNA translocation experiments with and without IL modification were conducted. It was found that the normalized average translocation amplitude of DNA with ILs showed a 2.1-fold enhancement and the average translocation time showed a 1.7-fold increase compared to that without ILs. Meanwhile, the proportion of partially folded and knotted events was significantly reduced, with knotted events approaching zero. Finally, an intriguing spike current enhancement phenomenon was observed. Employing ILs for DNA translocation modification can effectively decelerate the translocation speed, enhance SNR, reduce folding rates, and consequently advance high-precision DNA detection technology.