Dilution induced self-assembly of a dendrimer host-guest system

Interactions between nanoparticles are important in a range of phenomena including protein aggregation and crystallization, re-entrant phase transitions, assembly of nanoemulsions and the organization of nanoparticles into nanowires. Often these interactions are anisotropic, or in other words they are not evenly distributed on the particle. In the research shown in the animation, we make use of supramolecular (or non-covalent) chemistry to assemble nanoparticles with small hydrophobic patches. The number of patches depends on the coverage of hydrophilic guest molecules (shown in blue) that protect the hydrophobic host molecule (shown in yellow). The coverage in turn, depends on the concentration of guest and host molecules in solution. In most systems assembly of nanoparticles into larger structures occurs at high concentration and dilution causes them to be disrupted. In our systems the opposite is observed! Dilution of a solution of host-guest complexes (indicated in the animation) leads to an increased number of attractive hydrophobic patches, which interact and drive assembly. In other words, this systems assembles upon dilution, seemingly defying the law of mass action. We predict that this study could help close the gap between complex biological and colloidal-like systems.

For more information, see http://dx.doi.org/10.1038/nnano.2009.232 or http://www.tue.nl/universiteit/facult... (in Dutch).

Animation: ICMS Animation Studio
Music: "Nebulas Night" by Jason Livesay