[BNC-grads-list] 11/14 Nanotech. seminar (Francesco Stellacci, MIT)

[Deborah S. Starewich]

Supramolecular Nanomaterials and Lithography
 
Friday, November 14, 2008
4:30 pm, Wetherill (WTHR) 201
 
Francesco Stellacci
Department of Materials Science and Engineering, Massachusetts Institute of
Technology, Cambridge, MA, 02139, USA

Specific molecules can spontaneously arrange on various surfaces forming
two-dimensional poly-crystalline mono-molecular layers called self-assembled
monolayers (SAMs). We will show that when mixed SAMs are formed on surfaces
with a radius of curvature smaller than 20 nm they spontaneously
phase-separate in highly ordered phases of unprecedented size. In the
specific case of mixed SAMs formed on the surface of gold nanoparticles, the
molecular ligands separate into 5 Å wide phases of alternating composition
that encircle or spiral around the particle metallic core. This new family
of nano-structured nano-materials shows properties solely due to this unique
morphology, both in terms of fundamental properties such as surface energy
and in terms of complex interaction with biological materials such as
proteins and cells.

Additionally, it will be shown how patterned DNA SAMs can be used as masters
for a novel printing technique for organic materials called Supramolecular
NanoStamping (SuNs). This method, like the DNA/RNA information transfer,
uses the reversible assembly of DNA double strands as a way of transferring
patterns from a surface onto another. One of the main advantages of SuNs is
that multiple DNA strands (each encoding different information) can be
printed at the same time, thus allowing for a complex chemical pattern to be
formed, much like Gutenberg movable type.
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