Flow characterization and patch clamp dose responses using jet microfluidics in a tubeless microfluidic device.

Background: Surface tension passive pumping is a way to actuate flow without the need for pumps, tubing or valves by using the pressure inside small drop to move liquid via a microfluidic channel. These types of tubeless devices have typically been used in cell biology. Herein we present the use of tubeless devices as a fluid exchange platform for patch clamp electrophysiology.

Subangstrom single-molecule measurements of motor proteins using a nanopore.

Techniques for measuring the motion of single motor proteins, such as FRET and optical tweezers, are limited to a resolution of ∼300 pm. We use ion current modulation through the protein nanopore MspA to observe translocation of helicase Hel308 on DNA with up to ∼40 pm sensitivity. This approach should be applicable to any protein that translocates on DNA or RNA, including helicases, polymerases, recombinases and DNA repair enzymes.

Creation and regulation of ion channels across reconstituted phospholipid bilayers generated by streptavidin-linked magnetite nanoparticles.

In this work, we explore the nature of ion-channel-like conductance fluctuations across a reconstituted phospholipid bilayer due to insertion of ∼100 nm sized, streptavidin-linked magnetite nanoparticles under static magnetic fields (SMFs). For a fixed bias voltage, the frequency of current bursts increases with the application of SMFs. Apart from a closed conductance state G(0) (≤14 pS), we identify four major conductance states, with the lowest conductance level (G(1)) being ∼126 pS.

Rapid fabrication and piezoelectric tuning of micro- and nanopores in single crystal quartz.

We outline the fabrication of piezoelectric through-pores in crystalline quartz using a rapid micromachining process, and demonstrate piezoelectric deformation of the pore. The single-step fabrication technique combines ultraviolet (UV) laser irradiation with a thin layer of absorbing liquid in contact with the UV-transparent quartz chip. The effects of different liquid media are shown.

On-chip stochastic resonance of ion channel systems with variable internal noise.

We induced stochastic resonance in planar lipid bilayer systems with alamethicin ion channels, and varied alamethicin concentration, membrane area, and applied voltage. We found that membrane-induced microphonic noise significantly affects the signature of stochastic resonance, and that this noise can be used to optimize ion channel-based biosensors.

Mechanical actuation of ion channels using a piezoelectric planar patch clamp system.

High-throughput screening of ion channels is now possible with the advent of the planar patch clamp system. This system drastically increases the number of ion channels that can be studied, as multiple ion channel experiments can now be conducted in parallel. However, due to tedious, usually pressure-driven mechanotransduction techniques, there has been a slow integration of this technology into the field of mechanosensitive ion channels.

Single-ion channel recordings on quartz substrates.

We show that a single-crystal quartz substrate provides a working platform for ion channel research. Single-crystal quartz is piezoelectric, so it can be nanomechanically actuated to perform precise membrane deformations. This, along with its superior noise properties, makes single-crystal quartz ideal for analyzing mechanosensitive ion channels.