book of abstracts - IM2NP

A B S T R A C T S MONDAY, JUNE 28 N A N O S E A 2 0 1 0
pioneering studies, it was for instance proposed to disperse colloids in water droplets, and take advantage of
the drying process that spontaneously organizes particles along ring-like patterns (1). This technique is
however inadequate to obtain complex patterns, and significant improvements were obtained using
hydrophobic polymeric micro or nano-patterned templates, on which a receding meniscus is applied to direct
the assembly of micro and nanoparticles (2).
In the report, we propose a novel approach to direct the assembly of micro and nano-particles on solid
supports. Our method is based on the fabrication of patterned poly-acrylamid (pAM) hydrogels, which are
covalently attached to silanized glass or silicon substrates. A patterned silicon substrate is laid on top of the
gel during its formation, so that the reticulated structure is imprinted with structural patterns. The gel is
initially enriched in water that evaporates, leading to the formation of polymeric structures typically 100-
1000 nm in height and 10-50 µm in width.
We demonstrate that micro and nano-particles spanning 3 orders of magnitude in size (10 nm – 10 µm)
spontaneously accumulate along the gel patterns. Directed assembly occurs in one single step over large
surfaces of ~cm 2 , it is directed by hydrodynamics, and it does not require any external manipulation.
Interestingly, the dynamics of this directed assembly process could be characterized using fluorescence
microscopy (data not shown), showing that water meniscus recede along the patterns imprinted on the
hydrogel, and direct the assembly of particles along the motifs.
We then assessed the yield of our technology by measuring the number of particles captured along linear
motifs vs. the total number of particles by fluorescence microscopy. This analysis showed that large density
particles fail to assemble along the patterns because sedimentation is faster than hydrodynamics assembly.
Our method is particularly efficient for organizing nanoparticles along complex motifs, as inferred from the
distribution of particles on square-shaped or eye-shaped patterns. In addition, hydrogels can be used as
sacrificial layers using oxygen plasma etching, which selectively removes organic compounds, such as
acrylamid. Gold colloids remain intact after this process, leaving a template readily adapted to perform a
second round of self-assembly.
Finally, our technology is readily adapted to bio-assays. Indeed, patterned surfaces with gold colloids can be
used to organize biomolecules such as DNA using thiol chemistry. In addition, we were able to chemically
functionalize our hydrogels to make them suitable for cell culture. Taken together, we show that polyacrylamid
hydrogels are versatile materials for bio-assays and directed assembly.
(1) Deegan et al., Nature 389, 827 (1997)
(2) Malaquin et al., Langmuir, 23, 11513 (2007)
18H10-18H30
Quantum Confinement approach for the self-assembly process of peptide and
proteins structures.
Nadav Amdursky, †, ‡ Ehud Gazit, † and Gil Rosenman ‡ .(†Department of Molecular Microbiology
and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978,
Israel‡Department of Electrical Engineering-Physical Electronics, School of Engineering, Tel Aviv University, Tel
Aviv, 69978, Israel)
Peptide nanostructures, made by a self-assembly process of short peptide building blocks, represent a novel
class of bio-inspired nanostructural materials. The inspiration for the studied peptide building-blocks is from
the core recognition motif of the Alzheimer's disease, the diphenylalanine element. The dipeptide, which
composed from two phenylalanine residues (FF), can self-assemble into peptide nanotubes (PNT). This
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