SKM 2023 – scientific programme

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BP: Fachverband Biologische Physik

BP 1: Membranes, Vesicles, Synthetic Cells

BP 1.4: Talk

Monday, March 27, 2023, 10:15–10:30, BAR Schö

Controlling phase separations and reaction kinetics in microfluidically trapped droplets — •Sebastian W. Krauss, Paula Girones Paya, and Matthias Weiss — Experimental Physics I, University of Bayreuth, Germany

Droplet-based microfluidics is an efficient and versatile tool to study biomimetic reactions and self-organization in selected geometries and small volumes. It is also frequently used to perform high-throughput experiments, e.g. as selection platforms for directed evolution or for personalised medicine. While elaborate techniques are available for the production of picoliter-sized droplets, there is an increasing demand for subsequent manipulation and control of the droplet interior after production. Here we report on a straightforward method to rapidly and reversibly adjust the size of single to several hundred double-emulsion droplets in a microfluidic sieve by varying the osmotic pressure, leading to a change in concentration of enclosed molecules. We show that this approach allows for driving reversible demixing transitions of a biomimetic binary fluid which can be used to control the kinetics of enclosed enzymatic reactions. We also show that changing droplet sizes can be exploited for a reversible denaturing of double-stranded DNA, which may eventually allow for an osmotically driven PCR in small droplets.