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Projekt Druckansicht

Selbstorganisation DNA-basierter Dendrimere im Bulk und auf Oberflächen

Fachliche Zuordnung Statistische Physik, Nichtlineare Dynamik, Komplexe Systeme, Weiche und fluide Materie, Biologische Physik
Experimentelle Physik der kondensierten Materie
Theoretische Physik der kondensierten Materie
Förderung Förderung von 2016 bis 2020
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 314332205
 
Erstellungsjahr 2022

Zusammenfassung der Projektergebnisse

This project, a collaboration between researchers in Austria and Germany, successfully demonstrated the experimental realization of "cluster crystals" - a novel state of matter predicted theoretically two decades ago by the Austrian group. These structures are formed by self-assembly and hold significant potential for creating new materials with tailored properties. The core achievement lies in designing and synthesizing purely repulsive DNA-based building blocks that can form clusters and which under further compression spontaneously organize into periodic lattices where each lattice site is occupied by a cluster of several molecules. The project focused on two main areas: bulk self-assembly and interface organization. In the bulk, researchers created "all-DNA dendrimers" - branched, tree-like nanostructures composed entirely of DNA. Detailed studies revealed how these dendrimers fold and respond to conditions like salt concentration, providing crucial insights for controlling their assembly. Specifically, they observed anomalous liquid-like behavior in concentrated solutions where the stiffness of the dendrimer scaffold dictated organization. Furthermore, by attaching thermo-responsive polymers to these DNA scaffolds (creating dendritic-linear block polymers), they achieved hierarchical self-assembly into complex structures like bi-continuous double-gyroids, lamellae and hexagonal cylinders. Most notably, this work culminated in the creation and observation of equilibrium cluster crystals composed of DNA-based triblocks. These crystals exhibited remarkable adaptability, maintaining a consistent lattice spacing even as concentration varied - a hallmark predicted by theory. The second area explored self-assembly at interfaces, initially aiming to pattern surfaces with star-shaped DNA tiles. While prior publications from other groups covered similar ground, the project pivoted to investigate dense spherical brushes formed by ultra-long DNA fragments anchored to colloidal particles. Surprisingly, these brushes did not exhibit the expected crystallization with increasing density. Instead, they showed a non-monotonic behavior: shrinking, aggregation, and only at very high densities did crystallization occur. This was attributed to osmotic pressure from counterions and short-range attraction between DNA fragments, tunable by salt concentration. In addition, the role of these weak attractive forces in directing DNA assembly is studied in detail. Selective screening of these attractions, originated by the "blunt-end stacking" mechanism, allowed for encoding specific directionality in linear DNA duplexes, leading to the formation of novel smectic phases. Overall, the project significantly advanced our understanding of DNA self-assembly and its potential for creating novel soft matter materials. The ability to control interactions at the molecular level, particularly through scaffold design and blunt-end stacking, opens avenues for engineering crystalline phases with tailored macroscopic properties. The findings have already resulted in several high-impact publications and lay the groundwork for future advancements in structural DNA nanotechnology.

Projektbezogene Publikationen (Auswahl)

 
 

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