Fabrication and analysis of SiN nanopores for direct DNA sequencing

This paper summarizes the latest developments regarding solid-state nanopores achieved in our laboratory. For direct DNA sequencing with solid-state nanopores, a simple method has been developed to precisely fabricate nanopores with diameters of 1 to 3 nm. By measuring DNA translocation events through the fabricated nanopores, it was confirmed that single-stranded DNA (ssDNA) can pass through nanopores with diameters as small as 1.2 nm. In addition, it was discovered that the translocation speed of ssDNA is higher than that for double-stranded DNA (dsDNA) by three or four orders of magnitude. This difference in speed was explained by a difference in the forces acting on the DNA. From molecular dynamics (MD) simulations, it was found that the force of solution-DNA interactions on dsDNA is approximately 10 times larger than that on ssDNA during DNA translocation through a nanopore.