Planar microelectrode-cavity array for high-resolution and parallel electrical recording of membrane ionic currents

Abstract

Increasing the throughput and resolution of electrical recording of currents through ion conducting channels and pores is an important technical challenge both for the functional analysis of ion channel proteins and for the application of nanoscale pores in single molecule analytical tasks. We present a novel design based on sub-picoliter-cavities arrayed in a polymer substrate and endowed with individual planar microelectrodes that allows low-noise and parallel electrical recording from ion channels and pores. Resolution of voltage-dependent current transitions of alamethicin channels as well as polyethylene-glycol-induced blocking events of alpha-hemolysin nanopores on the submillisecond time scale is demonstrated using this device.

Screening ion-channel ligand interactions with passive pumping in a microfluidic bilayer lipid membrane chip

“…Note that this manual method of forming bilayers could be automated as described. 9 For a-HL experiments, the protein was added from the cis side (top reservoir) with blocker added from the trans side (flow channel).…”

“…Many authors have created bilayers across micro-cavities but because of the closedcompartment design, these techniques do not allow access to both sides of the bilayer, [9][10][11] precluding electrophysiological measurements with asymmetric buffer solutions. Such conditions are often required for ion channel measurements, for example, electrophysiological characterization of the potassium channel KcsA requires an acidic pH on one side of the bilayer.…”

“…Parallel recording techniques from multiple bilayers are being pursued 7,8 and improvements in bilayer stability and the ease of bilayer formation have been demonstrated, for example, through the use of smaller apertures over micro-cavities and nanopores. [9][10][11][12] Although small apertures are preferable for stable bilayers, the smaller integrated Ag/AgCl electrode can restrict recording time to a few hours. 9,12 Furthermore, the probability of ion-channel incorporation into bilayers is proportional to the surface area, 13 therefore large-area bilayers are desirable but these are often unstable.…”

“…[9][10][11][12] Although small apertures are preferable for stable bilayers, the smaller integrated Ag/AgCl electrode can restrict recording time to a few hours. 9,12 Furthermore, the probability of ion-channel incorporation into bilayers is proportional to the surface area, 13 therefore large-area bilayers are desirable but these are often unstable. Stable large-area bilayers have been produced using tapered apertures of 20-30 lm diameter made from Si 3 N 4 septa of 240 nm thickness 14 but silicon-based materials introduce undesirable noise.…”

Investigating cellular electroporation using planar membrane models and miniaturized devices

“…Polymers with different chemical natures give different amounts of blockade of the current, depending on their interaction with the α-hemolysin pore, while the time duration of the blockade is directly related to the length of the polymer. [93][94]. Next to these analytical applications, α-hemolysin is also widely employed for more fundamental and biophysical studies on DNA molecules, for instance for uncoiling ssDNA and unzipping dsDNA (double-stranded DNA).…”