Modulation of current through a nanopore induced by a charged globule: Implications for DNA-docking

¹ Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia - Via Regina Elena 291, 00161 Rome, Italy
² Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma - Via Eudossiana 18, 00184 Rome, Italy
³ CNR-Istituto dei Sistemi Complessi - Via Dei Taurini 19, 00185 Rome, Italy
⁴ Scuola di Scienze e Tecnologie, Università di Camerino - Via Madonna delle Carceri, 62032 Camerino (MC), Italy
⁵ INFN, Sezione di Perugia - Perugia, Italy
⁶ CNR-IPCF, Consiglio Nazionale delle Ricerche, Dipartimento di Fisica, Università Sapienza - Piazzale A. Moro 2, 00185 Rome, Italy

Received: 5 August 2014
Accepted: 20 October 2014

Abstract

The passage of DNA through a nanopore can be effectively decomposed into two distinct phases, docking and actual translocation. In experiments each phase is characterized by a distinct current signature which allows the discrimination of the two events. However, at low voltages a clear distinction of the two phases is lost. By using numerical simulations we clarify how the current signature associated to the docking events depends on the applied voltage. The simulations show that at small voltage the DNA globule enhances the pore conductance due to an enrichment of charge carriers. At high voltage, the globule drains substantial charge carriers from the pore region, thereby reducing the overall conductance. The results provide a new interpretation to the experimental data on conductance and show how docking interferes with the translocation signal, of potential interest for sequencing applications.