The
concept of template-confined chemical reactions allows the synthesis
of complex molecules that would hardly be producible through conventional
method. This idea was developed to produce high quality nanocrystals
more than 20 years ago. However, template-mediated assembly of colloidal
nanocrystals is still at an elementary level, not only because of
the limited templates suitable for colloidal assemblies, but also
because of the poor control over the assembly of nanocrystals within
a confined space. Here, we report the design of a new system called “supracrystalline
colloidal eggs” formed by controlled assembly of nanocrystals
into complex colloidal supracrystals through superlattice-matched
epitaxial overgrowth along the existing colloidosomes. Then, with
this concept, we extend the supracrystalline growth to lattice-mismatched
binary nanocrystal superlattices, in order to reach anisotropic superlattice
growths, yielding freestanding binary nanocrystal supracrystals that
could not be produced previously