Electrochemical Characterization of Regularly-Aligned Nanopore Array Membranes Filled with Electrolyte Solutions and Their Use for Detection of Nucleic Acid Hybridization

Abstract

We report on the electrochemical characterization of regularlyaligned cylindrical nanopore arrays supported in silicon nitride membranes and preliminary results for the detection of nucleic acid hybridization on the nanopore walls. A range of nanopore arrays with diameters between 40 and 150 nm were examined. We tested the effect of pore diameter, number of pores, electrolyte concentration and surface chemistry on the conductance of the nanopore membranes. The pores were functionalized with singlestranded DNA and conductance measurements were performed before and after hybridization. In many cases, changes in current rectification were observed following hybridization, which is discussed as a strategy for nucleic acid hybridization and interactions. IntroductionNanopore electrochemistry has received significant attention in recent years as a technique for the detection of biochemical interactions (1). Measurements of biochemical events in nano-scale confinement offer a number of advantages over conventional bulk techniques. These include i) faster response times and shorter diffusion lengths due to the increased surface-to-volume ratios, ii) improved control of molecular transport through manipulation of the electrical double layer, iii) a move towards single-molecule biosensing, and iv) the ability to probe interactions on biologically relevant length scales. Additionally, recent advances in micro-and nano-fabrication techniques have improved the reproducibility of making such nano-scale detection systems.Electrochemical measurements are performed within nano-scale channels, typically supported within thin membranes. These can include single channels or arrays of channels. In the typical setup, the channel is filled with an electrolyte solution and a potential is applied across the membrane. Geometric and surface properties of the channels can be determined from conductance measurements, and a variety of techniques can be used to detect biochemical interactions within the pores.To explore the use of arrayed nanopore membranes in biosensing, we present preliminary results for i) the characterization of nanopore array membranes using conductance measurements, and ii) electrochemical detection of nucleic acid hybridization at functionalized pore walls. Conductance measurements were performed on nanopore membranes in potassium chloride electrolyte over a broad range of ionic strengths. A variety of pore diameters, array sizes and surface treatments are tested, including biochemical functionalization with single-stranded DNA (ssDNA). Then, the effects of solution-based nucleic acids on the conductance of the nanopore membranes were measured for both untreated and nucleic acid-functionalized nanopores. In certain cases, current rectification behavior was observed, which is characterized by nonlinearity of the current-potential curve. Rectification has been attributed to asymmetric geometry and charge distributions on the device surface (2,3), and has been proposed as a method to detect biochemical interactions on the...

Electrochemical behaviour and voltammetric sensitivity at arrays of nanoscale interfaces between immiscible liquids

“…Previously, the fabrication of nanopore arrays in silicon nitride membranes by combination of electron-beam lithographic (EBL) patterning and reactive ion etching (RIE) was reported. 26,27 In such an approach, the geometric parameters were well-controlled and the arrays were close to the designed patterns. These nanopore arrays were then used in voltammetric experiments at water/ 1,6-dichlorohexane (gellified) interfaces.…”