Microfluidic platform for reproducible self-assembly of chemically communicating droplet networks with predesigned number and type of the communicating compartments

Abstract

We report a microfluidic system for individually tailored generation and incubation of core-shell liquid structures with multiple cores that chemically communicate with each other via lipid membranes. We encapsulate an oscillating reaction-diffusion Belousov-Zhabotinsky (BZ) medium inside the aqueous droplets and study the propagation of chemical wave-fronts through the membranes. We further encapsulate the sets of interconnected BZ-droplets inside oil-lipid shells in order to i) chemically isolate the structures and ii) confine them via tunable capillary forces which leads to self-assembly of predesigned topologies. We observe that doublets (pairs) of droplets encapsulated in the shell exhibit oscillation patterns that evolve in time. We collect statistical data from tens of doublets all created under precisely controlled, almost identical conditions from which we conclude that the different types of transitions between the patterns depend on the relative volumes of the droplets within a chemically coupled pair. With this we show that the volume of the compartment is an important control parameter in designing chemical networks, a feature previously appreciated only by theory. Our system not only allows for new insights into the dynamics of geometrically complex and interacting chemical systems but is also suitable for generating autonomous chemically interconnected microstructures with possible future use, e.g., as smart biosensors or drug-release capsules.

Cancer classification with a network of chemical oscillators

“…Such a phenomenon is frequently observed in experiments with networks of BZ droplets. 30 We can conclude by stating that classification is a transient phenomenon. The major part of data processing is done a short time after information is introduced into the network.…”

“…For millimeter size droplets the self-excitation does not appear in the whole volume of a droplet but starts in its center and propagates outwards. 30 Here, to account for this effect, yet make simulations simple, we assumed that an excitation spreads from the center of a droplet regardless of whether it self-excited or was triggered by another droplet. We introduced a propagation time of an excitation pulse t prop = 1 s, as the time required to travel the distance from the excitation origin to the contact area with the neighboring droplets.…”

“…Large networks of droplets with well defined parameters became accessible using microfluidic techniques. 30,31 It has been demonstrated that BZ-droplets are equally useful for information processing applications as the continuous medium. [32][33][34] Constructions of logic gates composed of subexcitable droplets 35,36 and oscillatory ones 37 have been described.…”

Droplet Microfluidics as a Tool for the Generation of Granular Matters and Functional Emulsions

“…new catalysts (Goodell et al, 2009;Kreutz et al, 2010). Droplet microfluidics is also a perfect tool to investigate the chemical communication of compartments comprising chemical oscillators such as the Belousov-Zhabotinsky reaction (Guzowski et al, 2016). An excellent overview of the various reactions performed in microdroplets can be found in a review by Elvira (Elvira et al, 2013) as well as in more recent publications (Guardingo et al, 2016;Wleklinski et al, 2016).…”

Using flow technologies to direct the synthesis and assembly of materials in solution

“…By generating liquid-segmented flow with aqueous primary amines and carboxylated perfluorocarbons, Easley et al created biocompatible emulsions which were evaluated using homogeneous protein assays, droplet polymerase chain reaction (PCR) and droplet recombinase polymerase amplification (RPA) [22]. Garstecki and co-workers investigated cell transport by generating multi-compartment droplets with bilipid membranes encapsulating Belousov–Zhabotinsky (BZ) solution [23]. The droplets were formed by encapsulation of two asymmetric droplets of aqueous BZ solution in a mixture of lipids and subsequent liquid segmentation by fluorocarbon oil creating a transparent and stable barrier for isolated membrane transport studies (Fig.…”