How do nanoaerosols get into the lungs

Development of ITEB RAS scientists

Official website of the Pushchino City Administration

Lung diseases can be treated with drugs in the form of nanoaerosols, scientists from the Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences, located in Pushchina, believe.

To create such drugs, it is important to understand how nanoaerosol particles penetrate lung tissue cells. Scientists created a model on which they studied how nanoaerosol particles interact with the lipid layer, and selected the conditions under which nanoparticles penetrate it. The results of their two-year work are published in the journal of the American Chemical Society "Langmuir" (Morozov et al., Ballistic Penetration of Highly Charged Nanoaerosol Particles through a Lipid Monolayer).

Lung diseases have long been treated with inhalers that spray medications in the form of aerosols – flying tiny particles and droplets. The disadvantage of this method is that aerosols settle in the upper parts of the lungs. Therefore, scientists pin their hopes on nanoaerosols that can penetrate deep into the lungs. Due to the very small particle size (10-9 m), the concentration of the drug needed for treatment is reduced by hundreds or more times. The problem, however, is that it is completely unclear what happens when nanoaerosol particles reach the surface of the pulmonary alveoli. After all, our lungs are covered with a layer of lipids (fats), and the medicine must penetrate through it. Are nanoaerosol particles capable of this? Scientists from the Laboratory of Nanostructures and Nanotechnology of the ITEB RAS, led by Viktor Morozov, showed for the first time that this is quite realistic for charged nanoparticles of the order of 100 nm.

For the experiments, the scientists chose the main lipid of the lungs – dipalmitoyl phosphatidylcholine (DPFC). They prepared a monolayer of this lipid on the surface of the water in the Langmuir bath, in a device adapted to measure surface tension. Charged nanoaerosols were obtained by electrospray of glucose solutions, proteins and other substances. Experimentally, it was found that when nanoparticles larger than one hundred nanometers are sprayed onto a monolayer, the surface tension of the lipid layer changes, becoming closer to the tension of the water surface, that is, the monolayer becomes less dense. "Nanoaerosol particles literally pierce it like bullets," co–author of the article, Candidate of Chemical Sciences Elena Shlyapnikova explained to the press service of ITEB RAS.

Next, the scientists put a thin film of mica on the bottom of the Langmuir bath and sprayed the nanoaerosol on the lipid layer again. Then the mica was taken out and studied using an atomic force microscope. They found clumps of lipid stuck together on its surface.

"We saw for the first time in the world that highly charged glucose nanoparticles penetrate the lipid monolayer," commented Elena Andreevna.

During the experiment, scientists discovered two effects competing with each other. It depends on them whether the surface tension of the lipid monolayer increases or decreases. If the nanoparticles are made too small, they do not have enough energy to break through the lipid layer. In addition, the nanoparticles must be highly charged and polar. If the molecules from which the nanoaerosol is made are nonpolar, then they can integrate into the lipid layer, making it denser.

"The surface tension will depend on the size and nature of the particle that falls on the surface of the lipid. I think we are close to understanding what is happening here," Elena Shlyapnikova is sure.

To see how nanoparticles fall on the lipid layer, what path the dislodged lipid molecules take, scientists set up an experiment on a synchrotron at the Kurchatov Institute. A joint publication summarizing the results of the experiments will be published in the journal "Crystallography" in early 2018.

The experiment continues at the European Synchrotron Center in Grenoble.

Portal "Eternal youth" http://vechnayamolodost.ru  19.09.2017