title: Electrostatic focusing of unlabelled DNA into nanoscale pores using a salt gradient.
abstract: Solid-state nanopores are sensors capable of analysing individual unlabelled DNA molecules in solution. Although the critical information obtained from nanopores (for example, DNA sequence) comes from the signal collected during DNA translocation, the throughput of the method is determined by the rate at which molecules arrive and thread into the pores. Here, we study the process of DNA capture into nanofabricated SiN pores of molecular dimensions. For fixed analyte concentrations we find an increase in capture rate as the DNA length increases from 800 to 8,000 base pairs, a length-independent capture rate for longer molecules, and increasing capture rates when ionic gradients are established across the pore. Furthermore, we show that application of a 20-fold salt gradient allows the detection of picomolar DNA concentrations at high throughput. The salt gradients enhance the electric field, focusing more molecules into the pore, thereby advancing the possibility of analysing unamplified DNA samples using nanopores.
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA.
authors.forename: Meni
authors.initials: M
authors.lastname: Wanunu
authors.forename: Will
authors.initials: W
authors.lastname: Morrison
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Rabin
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Grosberg
authors.forename: Amit
authors.initials: A
authors.lastname: Meller
mesh_terms: D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004058:Diffusion; D004563:Electrochemistry; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology; D009690:Nucleic Acid Conformation; D010316:Particle Size; D016062:Porosity; D012492:Salts / Q000737:chemistry*; D012996:Solutions; D055672:Static Electricity
chemical_list: D012492:Salts; D012996:Solutions; D004247:DNA