Nav: Home

The power of attraction

January 17, 2017

Engineered nanometer- and micrometer-scale structures have a vast array of uses in electronics, sensors and biomedical applications. Because these are difficult to fabricate, KAUST researchers are trying a bottom-up philosophy, which harnesses the natural forces between atoms and molecules such that microstructures form themselves.

This approach, a departure from the usual top-down approach, involves the etching away of material to leave the desired sculpted structure behind; however, because this approach can be tricky, expensive and time consuming, KAUST researchers became motivated to find a new approach.

Associate Professor of Chemical Science Niveen Khashab and her team and colleagues from the Imaging and Characterization Core Lab and the Max-Planck-Institute of Colloids and Interfaces in Germany demonstrated this bottom-up approach in the self-assembly of microscale toroids (doughnut-shaped forms), made of both inorganic and organic materials1.

A number of forces can bring atoms and molecules together. These include surface tension, electrostatic attraction and repulsion, and a weak fundamental force known as van der Waals interactions. The toroids created by Khashab's team were formed via metal coordination. A metallic sodium chloride atom, an amphiphilic (both hydrophilic and lipophilic) molecule called saponin and a polymer known as chitosan were combined and formed weak chemical bonds.

"This is a result of what is known as coordination-driven self-assembly," explained Khashab. "The metal ions interact with different chemical motifs leading to the formation of novel frameworks and morphologies."

Within just a few minutes, coordination bonding between the iron atoms and the oxygen and the hydrogen in the molecules initially drives the self-assembly of star-like nanostructures. Repulsive electrostatic and hydrophobic interactions then lead to the formation of toroids.

The toroids were approximately 3.9 to 4.8 micrometers in diameter and held their shape even a month after fabrication. Disassembly of the microstructures required five hours of mechanically stirring the solution.

There are numerous naturally occurring biological structures that take a toroid shape; for example, proteins and DNA of some types of viruses and bacteria self-assemble in this way. Many of these are known to play an important role in the formation of pores in biomembranes.

This research could help to build a better understanding of how these complex biostructures are created and provide a way of mimicking them at the molecular level.

"Next, we hope to prepare a new generation of these hybrid structures with a temperature-responsive gap size," said Khashab. "These toroid structures could be used as pockets for active catalysis and separation."
-end-


King Abdullah University of Science & Technology (KAUST)

Related Molecules Articles:

Discovery of periodic tables for molecules
Scientists at Tokyo Institute of Technology (Tokyo Tech) develop tables similar to the periodic table of elements but for molecules.
New method for imaging biological molecules
Researchers at Karolinska Institutet in Sweden have, together with colleagues from Aalto University in Finland, developed a new method for creating images of molecules in cells or tissue samples.
How two water molecules dance together
Researchers have gained new insights into how water molecules interact.
Hand-knitted molecules
Molecules are usually formed in reaction vessels or laboratory flasks.
How molecules teeter in a laser field
When molecules interact with the oscillating field of a laser, an instantaneous, time-dependent dipole is induced.
More Molecules News and Molecules Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...