Electro-osmotic trapping and compression of single DNA molecules while passing through a nanopore

• Published in: Analyst (London) Vol. 144; no. 18; p. 5381
• Main Authors: Yamazaki, Hirohito, Mizuguchi, Takaha, Esashika, Keiko, Saiki, Toshiharu
• Format: Journal Article
• Language: English
• Published: England 21-09-2019
• Subjects: DNA - chemistry; Electrophoresis; Fluorescence; Luminescent Measurements; Nanopores; Nucleic Acid Conformation
• ISSN: 1364-5528
• DOI: 10.1039/c9an01253b

Complicated DNA molecular behaviors exist during translocation into a nanopore because their large and coiled structure needs to unwind. In this work, we investigated DNA translocation dynamics through a 200 nm pore using a fast photon counting system (FPCS). We found that the dwell time of the DNA molecules depends on the inverse of voltage (τ∝V
) with a large constant term (∼1 ms). In other words, spherical fluorescence bead translocation involves electrophoresis as well as other additional factors. Our theoretical calculation suggested that one additional factor is electro-osmotic trapping associated with the instantaneous Brownian motion before and after translocation. Furthermore, compressed DNA molecular conformation was seen as a result of the increase of peak photon counts and the decrease of electrophoretic mobility with voltage. Our experiments showed that the polymers at the vicinity of a nanopore can be trapped and compressed, which is necessary to understand how to control the polymer translocation into a nanopore.