Ferrofluid-Based Droplet Interface Bilayer Networks

Abstract

Droplet interface bilayer (DIB) networks allow for the construction of stimuli-responsive, membrane-based materials. Traditionally used for studying cellular transport phenomena, the DIB technique has proven its practicality when creating structured droplet networks. These structures consist of aqueous compartments capable of exchanging their contents across membranous barriers in a regulated fashion via embedded biomolecules, thus approximating the activity of natural cellular systems. However, lipid bilayer networks are often static and incapable of any reconfiguration in their architecture. In this study, we investigate the incorporation of a magnetic fluid or ferrofluid within the droplet phases for the creation of magnetically responsive DIB arrays. The impact of adding ferrofluid to the aqueous phases of the DIB networks is assessed by examining the bilayers' interfacial tensions, thickness, and channel activity. Once compatibility is established, potential applications of the ferrofluid-enabled DIBs are showcased by remotely modifying membrane qualities through magnetic fields. Ferrofluids do not significantly alter the bilayers' properties or functionality and can therefore be safely embedded within the DIB platform, allowing for remote manipulation of the interfacial bilayer properties.

Encapsulating Networks of Droplet Interface Bilayers in a Thermoreversible Organogel

“…A wide variety of these pores and peptides have been incorporated in membrane mimics 57 – 63 . Here we focus on a pore forming toxin (alpha-hemolysin (αHL) 10 , 64 ) and voltage-gated peptides (alamethicin 11 , 65 ) as these are classically employed in DIB networks and provide points for comparison. These channels enable transport between adjacent droplets when appropriate conditions are met, and allow for stimuli-responsive droplet exchange 20 .…”

Characterizing the Structure and Interactions of Model Lipid Membranes Using Electrophysiology

“…The system’s equilibrium is defined by the contact angle between the droplets and it is utilized to monitor the behavior of membrane tension under changing conditions such as a varying electrical field [ 137 ]. DIBs present another advantage as they form asymmetric membranes in a simple yet controllable manner by dispersing different lipid mixtures in each droplet [ 138 , 139 ]. Furthermore, these emulsion systems allow for the assembly of membranous networks for investigating synthetic tissues [ 140 ] and bespoke model environment for studying transmembrane exchanges [ 141 ].…”

“…Not to be confused with the resting potential of natural membranes, model membrane potential discussed herein is the result of an imbalance between the leaflets electrostatics, induced by short-circuiting the model membrane through Ag/Ag-Cl electrodes [ 144 ]. Figure 7 sketches the transmembrane potential across (b) a symmetric model membrane formed from similar lipid leaflets and possessing a null overall potential, in comparison to (c) an asymmetric membrane where the leaflets are formed with two different lipids leading to the presence of a membrane asymmetric potential, Δφ ≠ 0 [ 138 , 139 , 144 , 155 ]. Membrane potential is a key element in conducting membrane electrophysiological studies and in characterizing membrane surface interactions.…”

Flexible Ferrofluids: Design and Applications

“…Magnetic microfluidics not only inherits systematic precise control over individual fluid and droplet of traditional microfluidics, but also is characterized by simple actuation strategy, flexible controllability, remote operation, as well as noninvasive manipulation ability . Thanks to these superior advantages, magnetic microfluidics is playing a vital role in biomolecule delivery, chemical reactions, bioseparation, polymerase chain reaction (PCR), and many other applications …”

“…[109,[128][129][130] Thanks to these superior advantages, magnetic microfluidics is playing a vital role in biomolecule delivery, [131] chemical reactions, [132,133] bioseparation, [134,135] polymerase chain reaction (PCR), [136,137] and many other applications. [126,138,139]…”