 Press Release
Angewandte Chemie International Edition 2008, 47, 2063–2066
doi: 10.1002/anie.200704609 Nr. 09/2008 Cellular Construction Methods EmulatedVersatile compartmentalized nanostructures by orthogonal aggregation of surfactants and gelatorsContact: Jan van Esch, University of Delft (The Netherlands)
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Preparation of Nanostructures by Orthogonal Self-Assembly of Hydrogelators and Surfactants
Not only is our body made of individual organs, our cells themselves are
made of tiny organelles, a variety of separate compartments that fulfill
different tasks. Such functional, nanostructured systems would also be
useful for technical applications, such as biosensors, self-repairing
materials, optoelectronic components, or nanocapsules. However, it has
not been possible to recreate structures with sufficient complexity in
the lab. Researchers in the Netherlands, led by Jan van Esch at the
Universities of Delft and Groningen as well as the BioMaDe Technology
Foundation, are now pursuing a new angle. As they report in the journal
Angewandte Chemie, they allow surfactants and gelators to form aggregates.
These aggregates coexist without interfering with each other and thus
make versatile, highly complex structures with separate compartments.
© Wiley-VCH
Cells contain various components, such as channels, “motors”, structural
frameworks (cytoskeleton), and “power plants” (mitochondria). In order
for these to form, their building blocks, mainly proteins and lipids,
must “recognize” each other and form the correct assembly by
self-aggregation. In addition, it is critical that compatible components
do not separate into different phases: when proteins fold, the
water-loving (hydrophilic) and water-repellent (hydrophobic) parts of
the molecule stay far away from each other and aggregate with
“like-minded” components. Biomembranes are formed when many small lipid
molecules aggregate such that their hydrophobic “tails” face inward
together and their hydrophilic “heads” point outward toward the aqueous
medium.
The Dutch team imitated this concept by using two types of
self-aggregating compounds: surfactants and gelators. Like the lipids in
natural membranes, surfactants have a hydrophilic segment and a
hydrophobic segment and aggregate into structures such as membrane-like
double layers or vesicles (bubbles). To imitate the forces involved in
protein folding—hydrogen-bridge bonds and hydrophobic interactions—the
team used a disk-shaped gelator, in which hydrophobic and hydrophilic
molecular components alternate in concentric rings. Just as for
proteins, like attracts like. This causes the disks to stack together
into columns, which forms long fibers, generating a three-dimensional
network in the solution to make a gel.
The researchers allow their surfactants and gelators to aggregate
together. In this process, the different components take no notice of
each other. This independent formation of different supramolecular
structures within a single system is called orthogonal self-aggregation.
This results in the formation of novel, complex, compartmentalized
architectures, for example, interpenetrating but independent networks or
vesicle configurations that coexist with gel fibers.
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