Pre-submission Thesis Presentation

The translocation of DNA through solid-state nanopores forms the basis of a powerful single-molecule sensing technique with applications in biomolecular analysis and sequencing. In this work, I investigate how nanopore geometry and translocation direction influence the electrical signatures generated during DNA transport through asymmetric conical nanopores. Using resistive pulse sensing experiments, translocation events of multiple lengths of DNA were studied over a range of voltages. The conductance blockade, translocation time, event charge deficit (ECD), and DNA folding characteristics were analyzed for both forward and reverse translocation. By correlating DNA fold length with conductance blockade, a new method for estimating nanopore sensing length using ECD measurements was developed. Analytical modelling of various nanopore shapes was performed to understand the geometric influence on the sensing length. Significant directional asymmetries were observed, including reduced conductance blockade, longer translocation times, larger ECD values, and a higher fraction of linear events during reverse translocation. Finally, finite-element simulations based on the Poisson-Nernst-Planck equations reveal that concentration polarization and the resulting electric-field asymmetry inside conical nanopores provide a physical explanation for the observed voltage and direction-dependent sensing lengths. Together, these results advance our understanding of DNA transport and signal formation in asymmetric nanopore sensors.

सभी का स्वागत है /All Are Welcome