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

[Image: see text] The ionic current blockades when poly(dT)(60) or dNTPs passed through SiN nanopores in an aqueous solution containing (NH(4))(2)SO(4) were investigated. The dwell time of poly(dT)(60) in the nanopores in an aqueous solution containing (NH(4))(2)SO(4) was significantly longer compared to that in an aqueous solution that did not contain (NH(4))(2)SO(4). This dwell time prolongation effect due to the aqueous solution containing (NH(4))(2)SO(4) was also confirmed when dCTP passed through the nanopores. In addition, when the nanopores were fabricated via dielectric breakdown in the aqueous solution containing (NH(4))(2)SO(4), the dwell time prolongation effect for dCTP still occurred even after the aqueous solution was displaced with the aqueous solution without (NH(4))(2)SO(4). Furthermore, we measured the ionic current blockades when the four types of dNTPs passed through the same nanopore, and the four types of dNTPs could be statistically identified according to their current blockade values.