  We study the problem of the self-assembly of nanoparticles (NPs) into finite
mesoscopic structures with a programmed local morphology and complex overall
shape. Our proposed building blocks are NPs directionally-functionalized with
DNA. The combination of directionality and selectivity of interactions allows
one to avoid unwanted metastable configurations which have been shown to lead
to slow self-assembly kinetics even in much simpler systems. With numerical
simulations, we show that a variety of target mesoscopic objects can be
designed and self-assembled in near perfect yield. They include cubes,
pyramids, boxes and even an Empire State Building model. We summarize our
findings with a set of design strategies that lead to the successful
self-assembly of a wide range of mesostructures.
