Spontaneous- and X-ray–Triggered Crystallization at Long Range in Self-Assembling Filament Networks

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Science  17 Dec 2009:
DOI: 10.1126/science.1182340


We report here crystallization at long range in networks of like-charge supramolecular peptide filaments mediated by repulsive forces. The crystallization is spontaneous beyond a given concentration of the molecules that form the filaments, but can be triggered by x-rays at lower concentrations. The crystalline domains formed by x-ray irradiation, with inter-filament separations of up to 320 angstroms, can be stable for hours after the beam is turned off, and ions that screen charges on the filaments suppress ordering. We hypothesize that the stability of crystalline domains emerges from a balance of repulsive tensions linked to native or x-ray induced charges and the mechanical compressive entrapment of filaments within a network. Similar phenomena may occur naturally in the cytoskeleton of cells, and if induced externally in biological or artificial systems lead to possible biomedical and lithographic functions.