What is a nanoparticle? According to the definition of petrologists, the size of a nano-object should be less than 100 nanometers. One of the paradoxical examples is the bubble. In fact, it is also a nano-object: when we inflate a bubble, it changes color and its walls become almost invisible. As has been proven by optical scientists, at this point its wall thickness is less than 100 nanometers, and thus it is Nanoscale.
However, scientists in the life sciences are much more likely to deal with nanoparticles in the form of round or elongated balls. Thus, nanoparticles have found important applications in oncology: they help to detect malignant formations, deliver medicines to them and defeat them.
Doctors administer chemotherapeutic drugs, which are essentially poisons, intravenous, and they are spread throughout the body, penetrating into the tissues, and poisoning them. Chemotherapy affects not only cancer cells, but also healthy tissues, and this is a serious problem which can be solved by nanoparticles. Nanoparticles do not get into most tissues: they cannot go beyond the walls of healthy vessels. However, tumor tissues have increased vascular permeability and nanoparticles can penetrate, as proven by Japanese pharmacologist Hiroshi Maeda in the 1980s. But the immune system quickly removes nanoparticles from the bloodstream. It is also a serious challenge for scientists.
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 cellular DNA.
The most sensitive to it are the smooth muscle cells of the heart. Under the influence of doxorubicin, heart rhythms change which can lead to heart failure or arrhythmia. If doxorubicin is administered in nanoparticles, its concentration in the body will become higher, but it will not cause serious complications. Thanks to nanoparticles, the side effects of chemotherapy have been significantly reduced, even though they are as effective as standard drugs.
Today many scientific groups try to collect own complexes - complex nano-complexes which will possess surprising properties and will essentially simplify cancer therapy. For example, it is possible to make nanocomplexes, which will break themselves when they get into a tumor. This will make it easier to spread the drug throughout the entire volume of malignancy. They can be made contrasting and distinguishable by existing medical imaging systems such as MRI, CT, ultrasound, and optical systems, the latter being widely used in the work with oncological animal models to study cancer therapy methods. Nanocomplexes can be made hybrid, combining organic and inorganic nature. Biohybrid complexes can be created in such a way that they are able to avoid capture by the cells of the immune system which will lead to better accumulation in tumors and metastases. And this is only a small part of the possibilities offered by nanotechnology.
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 from this variety is safe, some can seriously harm people. Nanotoxicology is studying the effects of nanoparticles on our bodies and possible approaches to reducing their effects.
You came to the beach and to protect yourself from ultraviolet rays, you applied the cream to the skin. It would seem that what can threaten? The fact is, nanoparticles of the cream can penetrate the skin cells, and damage them. Nanoparticles of organic filters, such as octocrylene or enzulisol, are particularly prominent. They discolour under the sun like clothes and lose their protective properties, so the cream has to be applied again. Organics can also lead to unpleasant consequences, such as skin irritation. Sunscreens do not only use organic compounds.
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 photostable, do not collapse under the influence of sunlight. However, they also have their disadvantages: under the rays of 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 the most effective sunscreen. They absorb light in a dangerous range — UVA type A, which can cause burns of various degrees and damage the DNA. As a result, a person may develop mutations that lead to the development of melanoma, a malignant formation.