Dwell Time Prolongation and Identification of Single Nucleotides Passing through a Solid-State Nanopore by Using Ammonium Sulfate Aqueous Solution

The ionic current blockades when poly-(dT)(60) or dNTPspassed through SiN nanopores in an aqueous solution containing (NH4)(2)SO4 were investigated. The dwell timeof poly-(dT)(60) in the nanopores in an aqueous solution containing(NH4)(2)SO4 was significantly longercompared to that in an aqueous solution that did not contain (NH4)(2)SO4. This dwell time prolongationeffect due to the aqueous solution containing (NH4)(2)SO4 was also confirmed when dCTP passed throughthe nanopores. In addition, when the nanopores were fabricated viadielectric breakdown in the aqueous solution containing (NH4)(2)SO4, the dwell time prolongation effect fordCTP still occurred even after the aqueous solution was displacedwith the aqueous solution without (NH4)(2)SO4. Furthermore, we measured the ionic current blockades whenthe four types of dNTPs passed through the same nanopore, and thefour types of dNTPs could be statistically identified according totheir current blockade values.

Automated summary

The study investigated the ionic current blockades when poly-(dT)(60) or dNTPs passed through SiN nanopores in an aqueous solution containing (NH4)(2)SO4. The dwell time of poly-(dT)(60) and dCTP in the nanopores was significantly longer in the aqueous solution containing (NH4)(2)SO4 compared to the solution without it. The prolonged dwell time effect was also observed when the nanopores were fabricated via dielectric breakdown in the aqueous solution containing (NH4)(2)SO4 and remained even after replacing the solution with one without (NH4)(2)SO4. Furthermore, the four types of dNTPs could be statistically identified based on their current blockade values when passed through the same nanopore.