Tuning the Chemical Communication of Oscillating Microdroplets by Means of Membrane Composition

Abstract

Abstract:Synchronization of dynamic elements via chemical communication is a widespread phenomenon in nature, and hence in many scientific fields such as in biology, physics and chemistry, where systems capable of giving and receiving informationare commonly found. In these systems coupling and synchronization between elements is achieved by messenger molecules diffusing from one element to others which trigger and spread a chemical reaction. Herein, in a biomimetic approach, we used a microfluidic system to confine a "chemical information generator", consisting of the far-from-equilibrium Belousov-Zhabotinsky (BZ) reaction in the aqueous core of monodisperse simple emulsion microdroplets. These microdroplets were surrounded by an oil phase containing the phospholipid 1,2-dimyristoylsn-glycero-3-phosphocholine (DMPC), doped with other amphiphilic molecules. Stabilized by the lipids layer contained in the oil phase, the drops could be brought in closest contact to be arranged in a 1D array, using a microfluidic device. The as-formed lipid membrane, at the contact surface, provided a diffusion path between the drops for the chemical species governing the dynamical behavior of the BZ oscillating reaction. We showed, that the coupling mediated by the membranes had mostly an inhibitory character, and that the communication could be controlled by the insertion of sodium tetradecyl sulfate and cholesterol as membrane dopants.Numerical simulations suggested, that the hydrophobic properties and the lipid packing at the interface were of paramount importance for the trans-membrane crossing of the pertinent chemical species.

Towards Functional Droplet Architectures: a Belousov-Zhabotinsky Medium for Networks

“…However, Torbensen et al . observed inhibitory coupling in a capillary-confined linear array of contacting MA BZ droplets, manifested as antiphase oscillations, with cyclohexane/chloroform containing synthetic phospholipids and an anionic detergent as the solvent phase 18 . Coupling over the lipid interface was almost completely abolished by the inclusion of cholesterol, postulated to react with the inhibitory bromine species, hence MA BZ droplets oscillated independently 18 , 19 .…”

“…BZ droplets-in-oil offer a wide scope for tuning droplet networks for the desired purpose. The interface can be adapted through the selection and combination of biological and synthetic surfactants 16 , 18 , while the reaction medium can be adapted by varying the concentration of its components over a range spanning orders of magnitude 21 . Accordingly the composition of BZ medium in published studies varies considerably.…”

A Model for Coupled Belousov-Zhabotinsky Oscillators with Delay

“…Networks of confined and relatively simple chemical oscillators are being used to model complex biological processes, such as cell-cell communication, neuronal signal transmission and passive diffusion across plasma membranes [26,27]. From an experimental point of view, the confinement of the Belousov-Zhabotinsky (BZ) reaction [3,28,29] in various dispersed systems [10], revealed to be a valid tool to understand universal synchronisation behaviours, when the network communication is mediated by either activatory or inhibitory signals.…”

Belousov–Zhabotinsky reaction in liquid marbles

“…To provide insights into these processes and the use of BZ media for the applications above, previous studies utilised the BZ reaction in spatially confining media such as thin hydrogel films [41], small droplets in microfluidic devices [32,[42][43][44][45][46][47][48][49][50][51][52], vesicles [53][54][55][56][57], emulsions [58], BZ-AOT emulsions [9-11, 17, 59-64], cation exchange resins [65][66][67][68][69][70][71] and 3D printed structures [42,72,73].…”