Droplet microfluidics is a powerful method for high throughput analysis, e.g. for screening reaction conditions, synthesizing particles, or single-cell analysis and other bioanalytical tasks. We employ droplet-based methods on an open platform, which is conceptionally similar to a multi-well plate, however, has a massively increased density of wells and hence, throughput [1]. Thousands of aqueous nL-droplets are deposited on a custom-made glass slide that has a defined hydrophilic-hydrophobic surface pattern. The droplets are covered by fluorinated oil and remain stable for several days. We can employ optical microscopy for droplet assessment as well as MALDI-MS imaging for analysis of the droplet content. In this presentation, I will show recent technological advancements of this platform, where we controlled the size of the droplets, formed chemical gradients and added and removed compounds at a defined time. We utilized the platform for the label-free kinetic analysis of an enzymatic reaction [2]. Further applications include highly-parallel cultivation of microbial growth, under optimum conditions as well as under antibiotic drug treatment. Here, we identify synergistic/antagonistic effects of drugs as well as unnormal cell behaviour including emergence of drug resistance.

References

[1] R. Strutt, B. Xiong, V. F. Abegg, P. S. Dittrich, Lab Chip 24 (2024), 1064-1075.

[2] M. Breitfeld, C. L. Dietsche, M. A. Saucedo-Espinosa, S. F. Berlanda and P. S. Dittrich: Ultrafast formation of microdroplet arrays with chemical gradients for label-free determination of enzymatic reaction kinetics, Small (2025), in print.