Nucleation and Division of Active Droplets

• Applicant: Professor Dr. Job Boekhoven
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576013390

This project explores active droplets: dynamic, non-equilibrium liquid compartments formed through fuel-driven chemical reactions. Unlike classical emulsions or coacervates that rely on thermodynamic equilibrium, active droplets are composed of molecules that are transiently activated and then spontaneously deactivated. This continuous turnover results in a flux of material in and out of the droplet, giving rise to behaviors that cannot occur at equilibrium—such as size control, suppressed nucleation, and spontaneous self-division. These phenomena have been predicted by theoretical models but remain largely untested experimentally. We aim to validate these predictions by constructing a modular library of chemically fueled peptides, whose activation-deactivation kinetics can be precisely tuned. Using this library, we will (1) test how droplet size correlates with kinetic turnover; (2) induce and observe spontaneous droplet division in steady-state systems upon sudden changes in fuel concentration; (3) study droplet behavior in spatial fuel gradients, mimicking cellular compartmentalization; and (4) quantify how short-lived building blocks can inhibit or delay droplet nucleation, revealing a kinetic control mechanism over phase separation. The project builds on our prior work developing carbodiimide-fueled peptide-based active droplets. These systems have already revealed novel dissipative structures, such as spherical shells and size-controlled emulsions. We will utilize state-of-the-art microfluidics, confocal microscopy, and kinetic modeling to study droplet dynamics in real-time. Each objective is designed to test theoretical predictions under controlled experimental conditions and will be executed in collaboration with experts in theory and modeling. By uncovering how chemical reaction kinetics govern active droplets, this project will advance our understanding of non-equilibrium self-assembly, provide design principles for life-like synthetic compartments, and offer new insights into the physical basis of biomolecular condensates. The findings may support future developments in synthetic biology, systems chemistry, and the design of adaptive soft materials.

• DFG Programme: Research Grants