Nanoflasks could offer a faster way to produce materials

Scientists at the Weizmann Institute of Science in Israel and the University of Illinois at Chicago have created self-assembling nanoflasks, with a span of just a few nanometers, that can accelerate chemical reactions. In the future, these nanoflasks might facilitate the manufacture of various industrial materials and perhaps even serve as vehicles for drug delivery.

Rafal Klajn of the Weizmann Institute's Organic Chemistry Department and his team were originally studying the light-induced self-assembly of nanoparticles. They were employing a method developed by Klajn in which inorganic nanoparticles are coated in a single layer of organic molecules that change their configuration when exposed to light. This change in configuration alters the properties of the nanoparticles, causing them to self-assemble into crystalline clusters.

Klajn and his team members found that when this happened with spherical nanoparticles of gold or other materials, empty spaces formed between the nanoparticles, like those between oranges packed in a case, and that these empty spaces sometimes trapped water molecules. This led them to suggest that these empty spaces could also trap other ‘guest’ molecules, allowing the spaces to function as tiny flasks for chemical reactions. A cluster of a million nanoparticles would contain a million such nanoflasks.

As reported in Nature Nanotechnology, when the scientists trapped molecules that tend to react with one another inside the nanoflasks, they found that the chemical reaction ran a hundred times faster than the same reaction taking place in solution. Being confined inside the nanoflasks greatly increased the concentration of the molecules and organized them in a way that caused them to react more readily. Enzymes speed up chemical reactions in a similar manner, by confining the reacting molecules within a pocket.

Although clusters of nanoparticles containing empty spaces have been created before, the advantage of the Weizmann Institute method is that the clusters are dynamic and reversible, so molecules can be inserted and released on demand. The clusters self-assemble when the nanoparticles are exposed to ultraviolet light, but then disassemble when exposed to regular light, meaning the same nanoparticles can be reused numerous times.

Moreover, the scientists found that by decorating their nanoparticles with a mixture of different chemicals, they could trap molecules inside the nanoflasks in a highly selective manner. For example, from a mixture of spiral-shaped molecules, they could cause left- or right-handed spirals to be trapped, a skill that can be particularly important for drug synthesis.

For future industrial use, the nanoflasks may prove useful in speeding up numerous chemical reactions, such as the polymerization reactions used to manufacture plastics. The method might also be applied one day to drug delivery: the drug could be delivered inside nanoflasks to the target organ and then released at the required time as the nanoflasks disassemble upon exposure to light.

This story is adapted from material from the Weizmann Institute of Science, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.