Directional coupling in spatially distributed nanoreactors.

Silica based hollow nanospheres filled with a reactant solution act as nanoreactors. A close packed ensemble of the nanoshells comprise a porous medium through which a chemical front can propagate. The front velocity decreases as the chemical signal, in the shape of a reaction-diffusion front, is transmitted from one sphere to the other due to the high curvature at the contact points. Experiments reveal that front propagation occurs through the cavity of the nanoshells because surface activity of filled nanoparticles itself cannot support chemical front across the medium.