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What is a nanoparticle? According to the definition of metrologists, the size of a nanoobject should be less than 100 nanometers. One paradoxical example is the soap bubble. In fact, it is also a nanoobject: when we inflate the bubble, it changes color, and its walls darken, becoming almost invisible. As it has been proved by optical scientists, at this point its wall thickness becomes less than 100 nanometers, and thus it is nanoscale. However, much more often scientists in the life Sciences are dealing with nanoparticles in the form of round or elongated balls. So nanoparticles have found important applications in Oncology: they help detect malignancies, deliver drugs to them and defeat them.
The main part of drugs in Oncology — classical chemotherapy. Doctors administer chemotherapy drugs, which are essentially poisons, intravenously, and they spread throughout the body, penetrating the tissues and poisoning them. Chemotherapy affects not only cancer cells, but also healthy tissues, and this is a serious problem that nanoparticles can help solve.
Nanoparticles do not get into most tissues: they can not go beyond the walls of healthy vessels. However, tumor tissues have increased vascular permeability, and nanoparticles can penetrate them, which was proved by Japanese pharmacologist Hiroshi Maeda in the 1980s. But the immune system quickly removes nanoparticles from the bloodstream. This is also a major challenge for scientists.
Why nanoparticles are better than traditional cancer drugs
The advantage of using nanoparticles in chemotherapy is undeniable: they are less toxic than standard drugs. For example, doxorubicin is an antitumor drug that damages the DNA of cells. The smooth muscle cells of the heart are the most sensitive to it. Under the influence of doxorubicin heart rhythms change, which can lead to heart failure or arrhythmia. If doxorubicin is administered as part of nanoparticles, its concentration in the body will be higher, but it will not cause serious complications.
Thanks to nanoparticles, the side effects of chemotherapy have significantly decreased, despite the fact that they are not inferior to standard drugs in efficiency. Today, many scientific groups are trying to assemble their own complexes-complex nanoconnections that will have amazing properties and significantly simplify cancer therapy. For example, you can make nanocomplexes that will self-destruct when they hit a tumor. This will facilitate the spread of the drug throughout the volume of malignancy. They can be made contrasting, distinguishable by existing medical imaging systems such as MRI, CT, ultrasound, as well as optical systems-the latter has been widely used in working with cancer animal models to study cancer therapy methods. Nanocomplexes can be made hybrid, combining organic and inorganic nature. Biogibrid complexes can be created so that they are able to avoid capture by cells of the immune system, which will lead to better accumulation in tumors and metastases. And this is only a small part of the opportunities offered by nanotechnology.
How nanoparticles can help protect against the sun
Another area where nanoparticles are used is toxicology. People inhale, consume particles of different substances and come into contact with them. However, not all particles of this variety are safe, some can seriously harm a person. Nanotoxicology studies the effect of nanoparticles on our body and possible approaches to reducing their impact.
The simplest example is sunscreen. You came to the beach and to protect yourself from ultraviolet rays, put the cream on the skin. It would seem that can threaten? The fact is, nanoparticles of the cream can penetrate into skin cells and damage them. Stand out nanoparticles of organic filters, for example, octocrylene or ensulizole. They are discolored under the sun, like clothes, and lose their protective properties, so the cream has to be applied again. More organic matter can lead to unpleasant consequences, such as skin irritation.
Not only organic compounds are used in sunscreens. In most modern products, the main component is inorganic particles, namely zinc oxide and titanium dioxide. These two metal oxides are good because they are photo-resistant, do not collapse under the influence of sunlight. However, they have their drawbacks: under the sun they become photocatalysts and begin to produce active radicals,which are safe because they remain in the cream.
Zinc oxide nanoparticles are considered to be the most effective sunscreen filter. They absorb light in a dangerous range-ultraviolet type A, which can lead to burns of varying degrees and damage DNA. As a result, a person may have mutations that lead to the development of melanoma — malignanc
But in 2016, a scientific article[1] reported that zinc particles, once on the skin, dissolve and enter the body. The stratum corneum of the epithelium-the top layer of the skin-is acidified by the sebaceous gland, which protects it from germs. As it turned out, nanoparticles dissolve in secret and penetrate into cells as ions.
Cell machinery is built on the fact that zinc is involved in cell regeneration and wound healing. But will the extra zinc that penetrates the skin after sunscreen be toxic to the body? We have been working on this issue for many years in the laboratory of Macquarie University (Australia) and Sechenov University, and now we are preparing the results of research for publication.
Why is this issue so important? Sunlight causes skin cancer. This is especially true for those who spend a lot of time under the sun. For example, two out of three Australians born in this country will be diagnosed with some form of skin cancer by the age of seventy. [2] Not all types of skin cancer are as malignant as melanoma, but I would like to protect myself from all. That is why in Australia launched a public campaign against this form of cancer. Skin cancer occurs when cells are damaged by excessive exposure to ultraviolet radiation from the sun. To protect people from melanoma, pharmaceutical companies are developing new compounds for sunscreens, including based on the latest achievements of nanomedicine.
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