|
Nanometer scale organisation of molecular
components on a copper surface, demonstrating sorting of two sizes
of molecules through molecular self-selection. The spacing between
molecular rows is about 1 nanometer (0.000 000 001 meter).
Image: Forschungszentrum Karlsruhe und
Max-Planck-Institut f�r Festk�rperforschung Stuttgart
|
In the Proceedings of the National Academy of
Sciences of the USA, the scientists from the research groups of Klaus
Kern at the Max Planck Institute for Solid State Research in Stuttgart
(MPI) and of Mario Ruben at the Karlsruhe Institute of Technology (KIT)
explain that this observation of molecular organization at surfaces
may lead to further insight of how simple, inanimate molecules can
build up biological entities of increasing structural and functional
complexity, such as membranes, cells, leaves, trees, etc. "The ability
of molecules to selectively sort themselves in highly organized
structures is a fundamental requirement for all molecular based
systems, including biological organisms," explains Prof. Dr. Klaus
Kern, director of the Nanoscale Science Department at the MPI.
Dr. Mario Ruben�s research team at KIT is responsible for designing
molecules with built-in instructions, which when read out activate the
self-selection process. He comments: "Spontaneous ordering from random
mixtures only occurs when built-in instructions are carefully designed
and sufficiently strong to initiate successful self-selection."
Scientists at the MPI directly observe the basic step of
self-selection by imaging grid-like assemblies of molecules, which
have sorted themselves by size. The features of the grid pattern are
about one nanometer in size (0.000 000 001 meters), so small that they
can only be imaged using state-of-the-art, ultra sensitive microscopy
techniques. "Creating such miniscule architectures with features 50
000 times smaller than a hair is not a simple task," according to Dr.
Steven Tait of the MPI. "Carving these nanometer structures with
current technology would be inefficient and extremely expensive. Our
strategy is to utilize instructed building blocks which can arrange
themselves into desired structures."
The molecules are placed on ultra-clean metal surfaces and heated
gently to enable motion, sorting, and organization. "The molecule
movement on the copper surface is restricted to two-dimensions, but is
still efficient enough to allow mixing of the molecules. By placing
the molecules on a surface, we have the enormous advantage of being
able to use specialized microscopes to �see� the nanometer scale
structures of the molecular assemblies," explains Alexander Langner, a
graduate student at the MPI and first author of the study.
The study was conducted by Alexander Langner, Dr. Steven Tait, Dr.
Nian Lin, and Prof. Dr. Klaus Kern of the Max Planck Institute for
Solid State Research and Dr. Chandrasekar Rajadurai and Dr. Mario
Ruben of the Karlsruhe Institute of Technology (KIT).
Professor Kern is the director of the Nanoscale Science Department at
the MPI and leads a large research team conducting a wide range of
studies related to the electronic, optical, and chemical properties of
novel materials at the nanometer scale. Dr. Ruben is the leader of the
research group "Functional Molecular Nanostructures" at the Institute
of Nanotechnology in Karlsruhe and has a long-standing competence in
the design and synthesis of instructed molecular components.
|
