Excitability and Oscillations of Active Droplets

Area of Science:

• Biomolecular condensates
• Synthetic biology
• Chemical kinetics

Background:

• The behavior of biomolecular condensates and synthetic systems is a rapidly developing field.
• Understanding the dynamic processes within these systems, such as formation and dissolution, is crucial.
• It remains an open question whether liquid droplets can exhibit self-sustained oscillations.

Purpose of the Study:

• To determine the minimal physicochemical requirements for self-sustained oscillations in active droplets.
• To model the dynamics of droplet formation and dissolution using nonequilibrium thermodynamics.

Main Methods:

• Development of a simple theoretical model with two chemical components.
• Governing diffusive and chemical fluxes using nonequilibrium thermodynamics.
• Analysis of droplet volume dynamics in response to fueling strength.

Main Results:

• A single active droplet exhibits a saddle-node bifurcation in volume with increasing fueling.
• The addition of a secondary chemical reaction induces excitability in the active droplet.
• Sufficient fueling leads to the emergence of self-sustained oscillations in droplet volume.

Conclusions:

• Active droplets can achieve self-sustained oscillations under specific nonequilibrium conditions.
• The study identifies key physicochemical prerequisites for oscillatory behavior in synthetic and biomolecular systems.
• This work provides a foundation for designing dynamic active droplets with tunable behaviors.