Interdroplet bilayer arrays in millifluidic droplet traps from 3D-printed moulds

Abstract

In droplet microfluidics, aqueous droplets are typically separated by an oil phase to ensure containment of molecules in individual droplets of nano-to-picoliter volume. An interesting variation of this method involves bringing two phospholipid-coated droplets into contact to form a lipid bilayer in-between the droplets. These interdroplet bilayers, created by manual pipetting of microliter droplets, have proved advantageous for the study of membrane transport phenomena, including ion channel electrophysiology.In this study, we adapted the droplet microfluidics methodology to achieve automated formation of interdroplet lipid bilayer arrays. We developed a 'millifluidic' chip for microliter droplet generation and droplet packing, which is cast from a 3D-printed mould. Droplets of 0.7-6.0 μL volume were packed as homogeneous or heterogeneous linear arrays of 2-9 droplets that were stable for at least six hours. The interdroplet bilayers had an area of up to 0.56 mm 2 , or an equivalent diameter of up to 850 μm, as determined from capacitance measurements. We observed osmotic water transfer over the bilayers as well as sequential bilayer lysis by the pore-forming toxin melittin. These millifluidic interdroplet bilayer arrays combine the ease of electrical and optical access of manually pipetted microdroplets with the automation and reproducibility of microfluidic technologies. Moreover, the 3D-printing based fabrication strategy enables the rapid implementation of alternative channel geometries, e.g. branched arrays, with a design-to-device time of just 24-48 hours.

Stable Free-Standing Lipid Bilayer Membranes in Norland Optical Adhesive 81 Microchannels

“…Alternatively, polymethilsiloxane (PDMS) is a transparent biocompatible material, which allows low-cost and simple fabrication, but its use for the formation of free-standing lipid bilayers is hindered by swelling and deformability issues in several organic solvents 13 , which are often required for artificial lipid bilayer formation 14,15 .…”

Cancer classification with a network of chemical oscillators

“…The lipid molecules cover the surface of droplets and stabilize them mechanically. 23 When two droplets come in contact, the lipids form a bilayer at the connection surface 28 that enables communication. 23,[25][26][27]29 This is so because molecules of the BZ activator can diffuse through the bilayer and excite the medium behind, triggering a chemical wave in the neighboring droplet.…”

Building interconnected membrane networks

“…Therefore, it has not been verified electrically that DIB membranes have stably formed in the devices. However, using a 3-D printed mold, droplets on the order of 0.7e6 mL were trapped in a fluidic device (King, Jones, Morgan, de Planque, & Zauner, 2014). In some instances, electrical access was possible via holes in the top of the device.…”