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Content archived on 2024-05-29

Phase diagram of DNA decorated colloids

Final Activity Report Summary - DIAGEL (Phase Diagram of DNA decorated colloids.)

New materials can be created by the controlled self-assembly of particles, using a bottom-up approach. Selective adhesion, through the specificity of DNA hybridisation has emerged as a powerful tool. DNA oligonucleotide coupling is an ideal way to interface particles via controllable and tuneable interactions. This has important consequences for building functional devices with novel properties for optical, electronic and bio-medical applications. Control of the valence of the elemental building blocks is a crucial issue for the efficient functionality of the particles. Controlling the length and sequence of the DNA strands grafted onto a core particle makes it possible to modulate the strength of the interaction and thereby alter the temperature or concentration at which assembly occurs via DNA hybridization.

The behaviour of an experimentally realised model for nanoparticles functionalized by four single strands of DNA in a tetrahedral configuration, has been characterized and it has been shown that it presents a rich phase diagram with at least three critical points and four thermodynamically distinct amorphous phases. These phases consist of a hierarchy of interpenetrating networks. Thus, bonding specificity of DNA provides an effective route to generate new materials with polymorphic behaviour, or to create structured materials with novel properties. The influence of the anisotropy of the attractive interaction has been also investigated for simple colloidal systems in order to provide a route map to the phase behaviour of more complex anisotropic systems.