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Scientists discover how to heat plasma nanoparticles to fight cancer

One promising approach to anti-cancer treatment is the use of plasmonic nanoparticles, which can be delivered to tumors, which are acted upon by laser pulses, which will create areas of very high pressure and pressure, and the surrounding tumor cell membranes will rupture. .

In the course of their calculations, Siberian scientists discovered that strong heating changes the plasmonic properties of the molecules, and as a result, their therapeutic efficacy may deteriorate.

Plasmonics is based on excitation of simultaneous oscillations of conduction electrons in nanoparticles (mostly gold) using light. It can become the basis for the development of various optoelectronic systems, but also new types of treatment. Nanoparticles can be inserted into a cancerous tumor and irradiated with a laser – this way they will receive additional energy due to surface plasmon resonance.
Excess energy will be released in the form of heat and will severely heat the surrounding pathogenic tissues, as well as create high pressure. Under these conditions, cells rupture and die.

Says Dr. Sergey Polyotov, Principal Investigator and Director of the International Research Center for Spectroscopy and Quantum Chemistry, Siberian University.
“Although plasmonic effects are well studied at the moment, we do not have much data on how temperature affects plasmonic nanoparticles, especially in the 5-10 nm region, where classical electromagnetic theory methods do not apply due to quantum and quantum effects from The methods are practically impossible to use due to limited computational resources. When heated, nanoparticles can change shape, melt, and begin to evaporate, all of which will change their optical properties, and hence the efficiency of flour operations, which are important for a number of applications.”

The scientists simulated heating gold nanoparticles to a melting temperature of 1,064 degrees Celsius – and higher. They were aided in their calculations by their unique mathematical model, which allows them to study nanoparticles with a size of 5-15 nanometers.

It turns out that with increasing temperature, the amplitude of atomic vibrations also increases, and they only slow down near the melting point. Further growth continues, and eventually the metal passes into a gaseous state, and the nanoparticles undergo decay.
It all starts from the surface, and as you approach the 1064°C mark, the process spreads throughout the entire volume.

Vibrations of atoms (also called phonons) even before the transition of the metal to the liquid state leads to the disappearance of plasmonic properties. This is due to the fact that they interact with freely moving electrons in the crystal lattice, slowing them down – electromagnetic waves cannot propagate and quench.

Comments Dr. Sergei Karpov, Professor at Siberian University and researcher at the International Research Center Spectroscopy and Quantum Chemistry.
“The mechanisms we describe are often overlooked, yet they can radically change the properties of plasmonic nanoparticles. This is especially important in conditions where a pulsed laser with a high radiation intensity is used – it imparts high energy to a medium containing nanoparticles, but in At the same time, the nanoparticles themselves are very hot.”

Summarizes Dr. Valery Gerasimov, researcher at the International Research Center.
The studied effects are interesting not only for the heating of cancer cells, but are also important for the creation of many different optoelectronic devices, and various sensitive sensors based on meat-eating effects.
They can now be required in the development of new generations of computer microcircuits.”

– The results of the work carried out with the support of a grant from the Russian Science Foundation (RSF) can be found on the pages of the Nanoscale

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