These results closely depend on the quality and geometry of the nanopores used, PF-6463922 research buy most of which focus on the small nanopores with the dimension comparable to the analyzers to achieve an optimal solution. Even so, the capture rate of proteins is low in nanopore experiments, and the electroosmotic flow against electrophoretic mobilities of proteins through silicon nitride membranes is dominant in small nanopores [9, 10, 18,

27, 33, 34]. Meanwhile, the adsorption interaction of proteins easily makes the small pore plugged [31, 32]. Therefore, to reduce these negative effects, nanopores with a larger scale are an alternative choice to analyze the varied targets. First, the arriving probability of protein in pore mouth is governed by free diffusion in bulk, which is referred to the pore geometry [9, 35]. A higher capture rate is expected for large nanopores [35]. And both electroosmotic effect and protein-pore interaction corresponding to the electric double layer along the charged inner wall

will be weakened in large nanopores; thus, more proteins will freely pass through nanopores [36, 37]. Additionally, more space in large nanopores is in favor of the surface GS-9973 purchase modification to change the physical and chemical properties of pores [38, 39], which will broadly expand the utility of nanopores for biological sensing. Certainly, the signal-to-noise ratio of the blockade current will inevitably deteriorate if the pore is too large. Hence, the choice of nanopore with a suitable dimension is critical for the design GF120918 mouse of nanopore many devices to understand the physical mechanism of molecules translocating through nanopores. Herein, bovine serum albumin (BSA), an important transport protein, is chosen to pass through a silicon nitride nanopore with a diameter of 60 nm. By applying a set of biased voltages, the protein swims through the large channel with a detectable signal-to-noise ratio of the blockage current. Comparing with small nanopores, a higher threshold voltage of 300 mV is observed

to drive the protein into the nanopore. With the voltage increasing, the current blockage events are greatly enhanced and are classified as a function of voltages. At the medium-voltage region, the amplitude of blockage current increases linearly while the dwell time decreases exponentially with the increasing voltage. Despite more free space in our large nanopore, the adsorption and desorption phenomenon of proteins has also been detected with a prolonged dwell time, but it is greatly weakened compared with small nanopore cases. With further increasing voltage, the protein is more likely to be destabilized by the applied electric forces. And a couple of proteins can pass through the nanopore simultaneously. Together, the experiments yield a new aspect of protein transport through a solid-state nanopore with a large scale.