Scientists from the Institute of Biochemistry and Physiology of Plants and Microorganisms, Saratov State University and the Moscow State Academy of Fine Chemical Technology have developed a new type of composite nanoparticles, which are successfully used for the delivery to the tissues of porphyrins. With the help of luminescence can control the distribution of nanoparticles in living tissue and enhance the photodynamic effect.
When receiving the composite particles are synthesized first silver nanokubiki size 30-60 nm. Further, based on these obtained gold-silver nanocages, which create a porous silica nanoshells of thickness from 20 to 100 nm. Then, the obtained particles are chemically modified and stabilized
Photodynamic therapy (FDP) — a method of treatment based on the same principle as chemotherapy, but the physical "additive". There are substances (called photosensitizers), which under the action of light with specific wavelengths cause in the surrounding solution photochemical reactions — in particular, facilitate the transition of the oxygen molecules in the excited energy (singlet) state. These excited oxygen molecules, in turn, destroy others find themselves near molecules such as organic. As a result, the amount of free radicals in a solution increases. When all these processes take place in a living cell, it has a devastating effect on her. If the photosensitizer substance has selective affinity specifically to the cells that must be killed, for example, a tumor, it may be used as a medicine. Only his action will necessarily have to supplement coverage of the affected tissue (now this is done using lasers).
Very often, the substance-photosensitizers are dyes. The very principle of photodynamic therapy opened at the turn of the XIX and XX centuries, German researchers who have worked with an organic dye acridine. If the solution acridine irradiate light with a wavelength falling within the absorption band of the substance, it kills repositories solution unicellular protozoa — ciliates-shoes. And without the toxic effects of radiation dye does not occur. Discovered the effect of the pharmacological institute professor at the University of Munich Hermann von Tappeyner tried to use it for treating fungal infections and skin tumors and without success. Now FDP used in the treatment of cancer, lymphoma, and certain bacterial infections (especially where the pathogens are resistant to antibiotics). Most often it is treated diseases of the skin, for a simple reason: the skin is the most accessible for the irradiation light.
So look silver nanokubiki who receive the first stage of the synthesis
The use of FDP due to some technical problems. Many substances are suitable for the role of photosensitizers are due to their chemical characteristics hydrophobic, i.e. are poorly soluble in water. But the internal environment of the body — it is an aqueous solution. To the active substance is better tolerated by the blood and enter the tissue, its molecules bind to the carrier particles. Such particles must be very small, smaller than bacteria. In other words, we are talking about nanoparticles.
Gold and silver nanocages coated with a layer of silicon dioxide having an average thickness of about 40 nm
The team of scientists from the Institute of Biochemistry and Physiology of Plants and Microorganisms, Saratov State University and the Moscow State Academy of Fine Chemical Technology, has developed a new type of composite nanoparticles, in which the gold-silver substrate is coated with a porous silica shell. Such particles have a size of about 40 nm — like small virus. They have been successfully used for the delivery to the tissues of one of the most important classes of photosensitizing agents — porphyrins. Furthermore, such particles luminesce under the influence of the visible light spectrum. Luminescence firstly helps to control distribution of nanoparticles in the living tissue, and secondly, the selection of the desired distance from the active ingredient molecules to the metal substrate can enhance the effect of photodynamic itself, improving the treatment of cancer.
Nanotechnology is used in the treatment of malignant tumors is not the first time. There is reason to believe that this will significantly help solve one of the major problems of modern humanity.
The work was carried out within the framework of the Federal Program "Research and scientific-pedagogical personnel of innovative Russia" for 2009-2013.
Source of information:
BN Khlebtsov, E. Panfilov, VA Hanadeev, AV Markin, GS Terentyuk, VD Rumyantsev, AV Ivanov, IP Shilov, N. G. Khlebtsov "Multifunctional composite nanoparticles based on gold-silver nanocages coated with silica and hematoporphyrin ytterbium." Nanotechnologies in Russia, Volume 6, № 7-8 (in press).