Accelerated ripening in chemically fueled emulsions

Chemically fueled emulsions are solutions with droplets made of phase-separated molecules that are activated and deactivated by a chemical reaction cycle. These emulsions play a crucial role in biology as a class of membrane-less organelles. Moreover, theoretical studies show that droplets in these emulsions can evolve to the same size or spontaneously self-divide when fuel is abundant. All of these exciting properties, i. e., emergence, decay, collective behavior, and self-division, are pivotal to the functioning of life. However, these theoretical predictions lack experimental systems to test them quantitively. Here, we describe the synthesis of synthetic emulsions formed by a fuel-driven chemical cycle, and we find a surprising new behavior, i. e., the dynamics of droplet growth is regulated by the kinetics of the fuel-driven reaction cycle. Consequently, the average volume of these droplets grows orders of magnitude faster compared to Ostwald ripening. Combining experiments and theory, we elucidate the underlying mechanism

Entwicklung von dissipativen supramolekularen Materialien - Von dem Konzept bis zur Anwendung

Inspired by nature, dissipative supramolecular self-assembly has been an interesting approach for the development of new materials. In this thesis, a known reaction network, based on acid-anhydride chemistry was used to design novel structures. Vesicles, colloids and emulsions were created using different building blocks. Especially interesting were the emulsions since they showed a unique zero-order decay and were able to encapsulate hydrophobic drugs. Further development led to a drug delivery platform with controlled zero-order release.Inspiriert von der Natur, war das Konzept der dissipativen supramolekularen Selbstassemblierung ein interessanter Ansatz zur Entwicklung neuer Materialien. In dieser Arbeit wurde ein bekanntes Reaktionsnetzwerk basierend auf Säure-Anhydrid-Chemie benutzt, um neuartige Strukturen zu gestalten. Mit verschiedenen Bausteinen konnten Vesikel, Kolloide und Emulsionen hergestellt werden. Besonders interessant waren die Emulsionen, da sie einen einzigartigen Zerfall nullter Ordnung zeigten und hydrophobe Medikamente einschließten. Durch weitere Entwicklungen resultierte dies in einer Plattform mit kontrollierter und konstanter Wirkstoffabgabe

Kinetic traps in chemically fueled self-assembly and how to overcome them.

Nature uses dynamic, molecular self-assembly to create cellular architectures that adapt to their environment. For example, a guanosine triphosphate (GTP)-driven reaction cycle activates and deactivates tubulin for assembly into microtubules and disassembly. Inspired by dynamic self-assembly in biology, multiple studies have developed synthetic analogs of assemblies regulated by chemical chemically fueled reaction cycles. A challenge in most of these studies is that molecules assemble upon activation but do not disassemble upon deactivation. In other words, they remain kinetically trapped, and the resulting assemblies are not dynamic. In this work, we show how molecular design dictates the tendency of deactivated molecules to remain trapped in the assembled state. We also show how molecular design can be used to tune the dynamics of the reaction cycle. Our work should result in chemically fueled assemblies that are truly dynamic in that dis-assembly immediately follows deactivation

Kinetic Control over Droplet Ripening in Fuel-Driven Active Emulsions

Active droplets are made of phase-separated molecules that are activated and deactivated by a metabolic reaction cycle. Such droplets play a crucial role in biology as a class of membrane-less organelles. Moreover, theoretical studies show that active droplets can evolve to the same size or spontaneously self-divide when energy is abundant. All of these exciting properties, i.e., emergence, decay, collective behavior, and self-division, are pivotal to the functioning of life. However, these theoretical predictions lack experimental systems to test them quantitively. Here, we describe the synthesis of synthetic active droplets driven by a metabolic chemical cycle and we find a surprising new behavior, i.e., the dynamics of droplet-growth is regulated by the kinetics of the fuel-driven reaction cycle. Consequently, these droplets ripen orders of magnitude faster compared to Ostwald ripening. Combining experiments and theory, we elucidate the underlying mechanism, which could help better understand how cells regulate the growth of membrane-less organelles.<br /