Dynamic Spirals of Nanoparticles in Light-Responsive Polygonal Fields

Nanoparticles tend to aggregate in an uncontrollable fashion once integrated into soft matter and consequently, self-assembling nanoparticles into large-scale, regular, well-defined patterns remains an ongoing challenge towards the design and realization of smart hybrid materials. The patterns of nanoparticles that have been reported in liquid crystals are static so far, and this lack of responsiveness extends to assemblies of nanoparticles formed in topological singularities and other localized structures of anisotropic matter. Here, we demonstrate the realization of light-responsive spirals of gold nanoparticles, by using a templating strategy that is common in the biological world. Specifically, we use polygonal fields of liquid crystals that incorporate molecular photo-switches in their composition, as light-responsive chiral templates. We also show that light modifies the period of the dynamic spirals of nanoparticles. These results confirm that using chiral liquid crystals as dynamic templates constitutes a versatile strategy towards soft photonic nanomaterials, and we anticipate that the possibility to control the period of the nanoparticulated pattern can find potential applications in the field of plasmonic sensing.