The use of SAMs, supported on flat surfaces or nanosized particles, to prepare interacting
interfaces requires the development of methodologies to ensure selectivity and
a certain degree of addressability. Selectivity is rather simple to achieve in either 2D or
3D SAMs by the introduction of specific functional groups and a large variety of
methods is indeed available to this aim. The addressability of these functional
groups is by far less simple and represents a tremendous challenge because it requires
control, down to the molecular scale, of the chemical reactions allowing the introduction
of specific features in macromolecular objects that are intrinsically heterogeneous
and dynamic because of their self-assembled nature. As far as 2D SAMs are concerned,
lithographic methods allow the preparation of patterned surfaces, where certain
functional groups can be easily positioned and addressed. This approach
cannot be applied to SAMs on nanoparticles. The possibility to organize at will functional
groups on soluble nanosized scaffolds such as nanoparticles could allow the
preparation of intelligent materials able to perform complex programmed tasks involving
other species such as biomolecules, or cells. On the other hand, the availability of
methods enabling one to precisely define the relative positions of a functional group
with respect to others is paramount in developing new materials, catalysts, and
devices. Some relevant achievements, such as the development of reliable methods
for the preparation of monovalent and divalent nanoparticles, disclosed the route to
aggregates with unprecedented topologies.
