Nanoparticles Designed to Destroy Cancer Cells

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For their new method of producing nanoparticles, an interdisciplinary research team, including members of the Kiel Nano, Surface and Interface Science priority research area and the Cluster of Excellence in Inflammation Research at Kiel University, made use of the so-called Leidenfrost effect: when a drop of water falls on a surface that is very much hotter than the boiling point of water, it begins to “hover” above the surface until it is fully vaporised. The water droplet can thereby be used as a microreactor in which small nanoparticles form.

The main interest of researchers working with material scientist and chemist Mady Elbahri is on the production of zinc peroxide nanoparticles in various sizes since zinc peroxide is regarded as a particularly effective oxygen supplier, even more so than simple zinc oxide. This makes it an interesting material for treating diseases such as cancer.

Production in a water bath

In order to systematically produce zinc peroxide particles of a certain size, the researchers looked closely at how the Leidenfrost effect works under water in particular, such as during deep-sea volcanic activity. They transferred these principles to their work in the laboratory. For synthesising the particles, they used a water bath on a stove rather than individual water droplets. At the bottom, they added a zinc acetate aqueous solution mixed with hydrogen peroxide. Here, it is particularly hot and there is a high concentration of ions, and this creates ideal conditions for forming particles. By changing the composition of the zinc acetate solution, the researchers varied the particle size in seven stages, from 70 to 680 nanometres.

The size of the nanoparticles is critical

For zinc oxide, there are already studies showing that it increases the proportion of reactive oxygen in cells excessively, and that this oxygen supersaturation leads to cell death. The initial results, recently published in the journal Nature Communications, indicate a potential application in cancer therapy in the long term. “In our experiments, we were able to demonstrate that nanoparticles of zinc peroxide damage cancer cells, and that this effect depends strongly on their size – in addition to the types of cancer cells and the concentration of the nanoparticles”, says Mady Elbahri.