Krasnoyarsk scientists have developed gold nanoparticles with unique spectral characteristics in the near-infrared range, which makes them promising for biomedical application, in particular, for hyperthermia treatment of cancer. The research results were published in The Journal of Chemical Physics.

Scientists from the Krasnoyarsk Science Center of the Siberian Branch of the Russian Academy of Sciences theoretically predicted and synthesized gold nanoparticle dimers connected to each other by conducting molecular linkers. They have a unique spectral property - absorption in the infrared region, due to which the new material may be of interest for biomedical applications, for example, in cancer therapy. The infrared range of radiation is less absorbed by the blood, so it passes deeper into the tissue, reaches malignant cells, affecting them.

The obtained particles consist of two gold nanoparticles connected to each other by special molecular linkers. Unlike many other materials, gold nanoparticles are biocompatible: they are not rejected by the body and do not have negative effects on it. The particle size is only 22 nanometers. The presence of a conducting material between two nanoparticles leads to the appearance of charge transfer plasmons, a special type of resonance associated with the periodic charge transfer through the “conducting bridge” from one particle to another. As a result, a new intense peak in the near-infrared range appears in the optical absorption spectrum. The resulting plasmon resonance, shifted to the red range, can be used to heat biological objects, for example, malignant tumor cells, with the aim to kill them.

“One of the most important applications of noble metal nanoparticles is anticancer therapy—oncological hyperthermia. It uses optical radiation to heat nanoparticles and, accordingly, selectively kill tumor cells when they are heated above 42 degrees Celsius. However, such radiation in the visible wavelength range, absorbed by ordinary nanoparticles, falls into the absorption band of tissues filled with blood, which sharply reduces the depth of light penetration into human tissues. The nanoparticles we developed have a plasmonic absorption peak in the infrared range, which is more transparent to biological tissues, which allows nanoparticles to be heated at a significantly greater depth inside the body. This opens up the possibility of using hyperthermia for the treatment of malignant tumors using the material we synthesized,” said Alexander Fedorov, Doctor of Physical and Mathematical Sciences, leading researcher at the L.V. Kirensky Institute of Physics SB RAS.

However, scientists note that despite all the advantages, the application of new particles requires further research and development. In particular, it is necessary to develop methods to control their properties and stability.

The research was supported by the Russian Science Foundation (project No. 23-12-2007) and the Krasnoyarsk Regional Science Foundation.