Surface Roughness Effects on Confined Nanoscale Transport of Ions and Biomolecules

Abstract

Biological channels, especially membrane proteins, play a crucial role in metabolism, facilitating the transport of nutrients and other materials across cell membranes in a bio‐electrolyte environment. Artificial nanopores are employed to study ion and biomolecule transport behavior inside. While the non‐specific interaction between the nanopore surface and transport targets has garnered significant attention, the impact of surface roughness is overlooked. In this study, Nanopores with different levels of inner surface roughness is created by adjusting the FIB (Focus Ion Beam) fabrication parameters. Experiments and molecular dynamics (MD) simulations are employed to demonstrate that greater roughness results from larger FIB beam currents and shorter processing times. Lower roughness increases the capture rate of biomolecules, while greater roughness enhances the normalized blockade current (ΔI/I0). The phenomenon of rougher nanopores are attributed to a barrier‐dominated capture mechanism and more likely to induce DNA folding. This transport barrier exists in rough nanopores by utilizing steer molecular dynamics (SMD) simulations to investigate the force profile of a dA10 DNA molecule during translocation is demonstrated. This work illustrates how surface roughness influences the ionic current features and the translocation of biomolecules, paving a new way for tunning the molecule transport in nanopores.

Single-Digit Nanobubble Sensing via Nanopore Technology

“…On the other side of the wafer, the silicon nitride layer and silicon oxide layer were removed using photolithography and RIE with a square of 320 μm × 320 μm. The free-standing silicon nitride membrane was obtained after removing the silicon substrate by a potassium hydroxide wet etching. − …”