Nanoparticles for burning out tumors
Russian scientists have created silicon nanoparticles that "burn" cancer
Physicists from Russia and Finland have created a new type of silicon nanoparticles that can be simultaneously used to destroy cancerous tumors by heating them to ultra-high temperatures, and to measure temperatures inside the body, according to an article published in the journal Nano Letters (Zograf et al., Resonant Nonplasmonic Nanoparticles for Efficient Temperature-Feedback Optical Heating).
"In the future, such nanosystems will allow targeted killing of cancer cells by heating, and real–time temperature control will save healthy cells from uncontrolled overheating," says Sergey Makarov from ITMO University, talking about the advantages of silicon nanoparticles.
In recent years, scientists have created several fundamentally new cancer treatments based on various organic or inorganic nanoparticles. In some cases, nanoparticles themselves serve as a means to remove the tumor, acting as a kind of "target", which is targeted either by immune cells or laser radiation that heats the particles and burns the cells.
As Georgy Zograf, the lead author of the article and Makarov's colleague at ITMO, adds, today most scientists use for these purposes nanoparticles of gold and other metals that absorb light and infrared radiation well and convert it into heat.
All of them have one common drawback – the temperature of these "nanogranates" is actually impossible to measure by how their radiation changes. Therefore, such nanoparticles, despite the high efficiency of their work, can destroy not only cancer, but also neighboring healthy cells, which prevents their widespread use. In addition, nanoparticles of many metals are toxic and dangerous to the cells themselves, which also imposes restrictions on their work.
Silicon nanoparticles, as scientists say, are devoid of both problems – their radiation spectrum changes when heated, and the particles themselves are easily decomposed by the body. On the other hand, physicists have long believed that silicon nanoparticles cannot be used as such thermal "grenades", since they absorb light energy much worse than pieces of gold and other metals.
As the experiments conducted by Russian and Finnish physicists have shown, this is actually not the case. They managed to warm up silicon nanoparticles to a temperature of 900 degrees Celsius by irradiating them with a red or infrared laser, similar to that found in CD players, and at the same time very accurately register changes in the heating of microscopic spheres up to their melting temperature.
Interestingly, silicon nanospheres turned out to be about four times more effective absorbers of light energy than gold nanoparticles, which allows them to be used for an equally effective fight against cancer, while reducing the laser power. This will additionally protect healthy tissues from damage or make cancer therapy more reliable due to the ability to flexibly control the particle heating temperature by changing the laser wavelength.
Drawing from the article in Nano Letters
In addition to the fight against cancer, such nanoparticles, as scientists note, can be used for other purposes – for example, to accelerate chemical reactions, as temperature sensors or a constituent element of other nanodevices.
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01.06.2017