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SOFt Interfaces: control of interfacial layers for biotechnological applications

Final Report Summary - SOFI (SOFt Interfaces: control of interfacial layers for biotechnological applications)

The goal of the project SOFI is to propose new solutions for the encapsulation of biological materials in microcompartments formed by water droplets in oil. The technology background -- droplet-based microfluidics -- has a tremendous potential for biological applications at a ultra-high throughput. Yet fundamental challenges have to be addressed for a reliable use of the technology.

The dynamics of surfactants at interfaces affects the macroscopic properties of emulsions or foams. One of the main challenge to fully control these systems is to measure the dynamics of the surfactant layers at small length-scales and short time-scales. For this purpose, microfluidics is a perfect tool as it provides the tools to control interfaces in a very reliable manner. The level of control achieved with this technique is tremendous: we can produce model emulsions usable to quantitatively measure dynamics properties not accessible otherwise. We make use of this type of control to design new experimental techniques to study interfaces in microfluidics. We measure the rate constants of adsorption and desorption of surfactants and make a link between these values and the stabilization conditions of emulsions. To the best of our knowledge there is no other experimental technique usable to make these measurements. This fundamental understanding of the dynamics of interfaces is relevant to optimize formulation of emulsions used in the industry but also to study why and how chemical reactions are favored in microcompartments. We have highlighted a mechanism related to the competition between the diffusion of the product synthesized at the droplet interface and the backward rate of the reaction. This process is universal and shows that reactions in micro-compartment are favored compared to bulk. This gives a 'pre-evolutionnary' advantage to micro-compartments in prebiotic chemistry, and could be a key to understand the emergence of large molecules from smaller ones. Moving from droplets used as simple microreactors to droplets acting as active microreactors is our next effort. We have shown that microfluidics is an essential ingredient to prepare new types of active compartments having properties mimicking those of living systems. We now chemically functionalize microreactors to program them with new functions that can not be obtained by other means.

In summary, droplet-based microfluidics offers the control of micro-compartments to understand fundamental processes at interfaces with a wide range of applications in physics, chemistry, engineering and biotechnology. In SOFI, we have unraveled the essential dynamic processes driving the performance of the formulations used in applications and developed new experimental solutions for encapsulation. Beyond this fundamental understanding, our results serve as a basis to construct new types of microcompartments making use of their chemical interactions with their surrounding environment providing new building blocks for the construction of systems having properties mimicking those of living systems.