Oxygen for the tumor
Scientists from Russia forced laser and nanoparticles to kill cancer faster
Russian and foreign biochemists have found out how nanoparticles capable of connecting with cancer cells produce oxygen when "illuminated" by a laser, and have understood how their effectiveness can be significantly increased. The results of their experiments were presented in the journal Scientific Reports (Sokolov et al., Residence time of singlet oxygen in membranes).
"In the future, we plan to select those photosensitive molecules and nanoparticles that will show maximum efficiency in our experiments. We will test their work directly on cancer cell cultures," said Oleg Batishchev, an employee of MIPT and the Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences in Moscow, whose words are quoted by the press service of the Russian Science Foundation.
A new arsenal of doctors
In recent years, foreign and Russian scientists are increasingly trying to use various nanoparticles to fight cancer, infectious diseases or to treat non-communicable diseases. As a rule, they are used as a kind of "containers" for the delivery of very dangerous toxins inside the tumor or the focus of infection.
In other cases, nanoparticles themselves serve as a means to remove tumors or as "killers" of microbes and viruses. They join them and act as a kind of "target" that attracts the attention of immune cells, or laser radiation is directed at them, heating particles and burning cells.
Particles of the second type, as Batishchev notes, work very well. They have been used for a long time to fight melanoma and other forms of skin cancer as part of the so-called photodynamic therapy.
As a rule, they consist of two components – substances that connect to the membranes of cancer cells, as well as special molecules capable of absorbing light energy and using it to produce atomic oxygen and other extremely aggressive oxidants. They destroy the shell of tumor cells and damage their DNA, which leads to the self-destruction of the tumor.
Despite the huge advantages of this therapy, including its high safety, lack of surgical intervention and low toxicity, it has one big drawback. The fact is that scientists do not yet fully understand how these nanoparticles interact with light and how their properties affect the rate of formation of oxidants.
Anti-cancer defense
Batishchev and his colleagues filled this gap by creating a system that allowed them to monitor the reactions between nanoparticles, light rays, the cell membrane and their environment. They found that the oxygen they produce does not behave in reality as predicted by observations of its formation in an "inanimate" environment.
"We have shown that the lifetime of these oxygen forms on the cell membrane is markedly different from previous estimates. These differences are comparable to the extent to which two–dimensional graphene films differ in their properties from ordinary "three-dimensional" carbon," the biochemist continues.
For example, scientists have found out that nanoparticles do not destroy cell proteins as effectively as the theory indicates. These differences were related to how the charged "tails" of fats in its membrane affect the movement of oxidants produced by light-sensitive molecules. They quickly neutralized oxygen and prevented it from penetrating into those parts of the membrane where proteins critical for maintaining its stability were concentrated.
All this, in turn, suggests that the efficiency of these nanoparticles can be improved by increasing their concentration on the cell surface or forcing them to penetrate deeper into the membrane, and not just "stick" to it. Whether this is true or not, Russian biochemists will check in the near future.
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