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.