The modern world is filled with all sorts of information. Especially interested in people the area of \u200b\u200bmedical discoveries. You can often hear about such a disofer as Pankov's glasses. Reviews of so many practitioners are pretty encouraging, but there are not such irrespective impressions as promised advertising of the device. What are miraculous glasses, and what is the essence of their application in the field of recovery of adults and children?

Methods of impact on the eyes of the quantum glasses of Professor Pankov

The essence of the innovative method of treating eye Pankov is to restore vision by impact on the retina of the eye of colored radiation. The structure of the human eye is such that it distinguishes the colors according to the cerebral pulse on certain nerve endings. When various color radiation is affected by the eyes in a fast pace, all the fabrics and nerve endings are excited, blood supply is improved and the revival of those areas that seem to do not perform their function.

A new apparatus used in many medical records to restore vision has positive feedback. Pankov's glasses, according to many specialists in the field of ophthalmology and color therapy, deserve the attention of those people who lose sight or have side effects from working at a computer.

In essence, Pankov's quantum glasses are a gym stimulator that improves the physiological purpose of each component of the eye apparatus. A lot of opinions today are focused around the topic, as well as pankov's quantum glasses. Reviews are both flattering and negative.

Where can I learn detailed information about Pankov's instrument?

Before the design of the device was approved and allowed for mass issuance to use in the medical sphere to treat people's vision, the author is a professor of Pankov - wrote interesting work on the topic of the possibilities of recovery of vision precisely with the help of the impact on the eyes of all shades of the rainbow.

What Pankov's glasses look, the feedback on this device can be found without any problems. But in controversial information from different sellers, it is not always possible to specifically understand what is still treating this device and how to apply it. Therefore, in most cases, those who really need help to restore in their vision are referred to explanations to the book of professor, describing the physiological significance of each color, is the "Rainbow of Transparency". Pankov glasses, reviews about them are directly related to the book.

Today, the medical instrument market is filled with fakes, the instructions of the sold devices in almost every second case include descriptions from the author's source, but they are not quite specific to their use in practice.

The book describes the methods of exposure to lighting, which is a warm-up. But not always exercises, such as observation of fish in aquarium with color lighting, gives effect. But deserved recognition due to the rhythm of his work received the device created by the author - the glasses of Professor Pankov. Feedback, of course, cannot give a detailed response about the efficiency of the device. To get a reliable grades for the recovery of vision, you need to know the opinion of professional ophthalmologists.

Without appointing an ophthalmologist, the device is not applied in practice. The effect of it can professionally evaluate only a specialist.

The effect of glasses on visual recovery

Pankov glasses affect the eye in this way:

  • due to the filled light signals, the eye muscles massage occurs; The spasm of the pupil is removed, which during the workout is narrowed, it expands;
  • due to the rhythmic operation of the eye apparatus, the outflow of intraocular fluid is improved, and the front camera of the eye gets the vibration of the image perception depth;
  • the abbreviation of the muscles improves blood circulation, due to which effective microcirculation in the retina, the nutrition of all tissues is improved, therefore, the visual perception is improved.

In most cases, Pankov's positive feedbacks are deserved when used as a simulator for the prevention of unpaid eye diseases, as well as to train vision of people, the professional scope of which is associated with a large load on sight: computer, accountants, cashiers, researchers, pilots.

Pankov glasses are prescribed by an ophthalmologist at the initial degree of cataracts, asthenopias, amblyopia, progressive myopia, glaucoma, strabism, myopia, developed hyperopia, retinal dystrophy.

If you can focus on positive feedback, Pankov glasses are also recommended to be used to prevent complications in the postoperative period if surgery was carried out in the eye area.

Factors for the use of glasses

  • Analyzing all feedback, Pankov glasses should be used as a simulator to office workers who do not actually break in their work while processing data on computer technology.
  • A positive about the devices respond to the students who are and in the afternoon, and at night to strain the vision of reading books.
  • Pankov's glasses and those who, instead of ordinary glasses, wears modern lenses, from which their eyes get tired and often blush.
  • In many situations, the ophthalmologist discharges trainings to the device, if confident in the threat of development of one or another eye disease.
  • Especially useful to apply the device at a specialist diagnosis - an accommodation spasm.

Possible contraindications of the application of an innovative simulator for sight

The use of Pankov's device with strong inflammatory processes of eyes, mental illness, oncology, diseases of the central nervous system, pregnancy, heavy forms of diabetes, tuberculosis of the lungs, restoration after a heart attack or stroke, and is not recommended for practicing children under three years old.

All "for" and "against" applying an appliance to restore vision

As mentioned above, very many, who had a chance to face Pankov's glasses in practice, note the positive effect after passing the course of treatment under the supervision of an ophthalmologist. The number of childcare patients in a general ratio exceeds the number of patients with the middle and old age category. Practice talks about the importance of correction at an early age.

People who decided to apply the device without appointing a doctor, the effect cannot be estimated professionally, therefore, there are many negative reviews that bind this discovery is nothing but other than the quantity.

Tips of professional ophthalmologists about the use of Pankov's glasses

Each ophthalmologist, before appointing a course of treatment with Pankov's glasses, always confronts a clear diagnosis. The device may not give positive shifts to improving the condition of view if the disease is too launched. Pancic glasses can be used only after drug treatment, after removing inflammation.

Where can I get Pankov's glasses?

What exactly should not be done, based on the above, it is to purchase the device through the online stores. The reason for this is a lot of fakes of an effective medical device and a lot of advertising.

Moreover, the advertisement of the device more emphasizes the attention of the buyer not on its gym, but on therapeutic properties. Particularly active Pankov glasses are offered on the sites of megacities. So, for example, an evaluation of the opinions about this apparatus of residents of St. Petersburg, which were given to acquire it through virtual sellers and experience in practice. If you study these reviews, Pankov glasses (St. Petersburg - not the only region, whose residents fell on the tricks of advertisers) caused a lot of negative characteristics and distrust of this innovation.

So it is worth recovering your vision to visiting an ophthalmologist, and if you buy the device, then only on the recommendation of the competent doctor who does not advise exactly badly.

« Quantum dots are artificial atoms whose properties can be controlled.»

J.I. Alferov, Winner of the Nobel Prize 2000. In physics for the development of semiconductor heterostructures for high-speed and optoelectronics

Quantum dots (CT) are isolated nanoobjects whose properties differ significantly from the properties of the volume material of the same composition. Immediately it should be noted that quantum dots are more like a mathematical model than real objects. And is due to this with the impossibility of forming completely separate structures - small particles always interact with the environment, being in a liquid medium or solid matrix.

To figure out what quantum dots, and understand their electronic structure, imagine an ancient Greek amphitheater. Now imagine that the scene unfascisives, and the audience ranks are filled with the public who came to watch the game of actors. So it turns out that the behavior of people in the theater is largely similar to the behavior of the electrons of the quantum point (CT). During the presentation, the actors move in the arena, without leaving the audience, and the audience themselves follow the action from their places and do not go down on the stage. Arena is the lower completed levels of the quantum point, and the audience ranks are excited electronic levels with higher energy. At the same time, as a viewer can be in any row of the hall, and the electron is able to occupy any energy level of the quantum point, but cannot be located between them. Buying tickets to the idea at the box office, everyone sought to get the best places - as close as possible to the scene. Indeed, well, who wants to sit in the last row, from where the actor's face does not consider even in binoculars! Therefore, when the audience is searched before the view of the presentation, all the lower rows of the hall are filled, as well as in the stationary state of the CT, which has the lowest energy, the lower energy levels are fully occupied by electrons. However, during the presentation, someone from the audience may leave their place, for example, because the music on the stage plays too loudly or just a neighbor is nice caught, and reconcile to a free top row. This is how and in CT, the electron under the action of external influence is forced to switch to a higher energy level, not occupied by other electrons, leading to the formation of the excited state of the quantum point. Probably, you wonder what happens with the empty place at the energy level, where was the electron - the so-called hole before? It turns out that the electron electron is connected with her charge interactions and can go back at any time, as well as the viewer can always change and return to the place marked in his ticket. A pair of "electron-hole" is called "exciton" from the English word "excited", which means "excited". Migration between the energy levels of the CT, similar to the rise or the descent of one of the audience, is accompanied by a change in the electron energy, which corresponds to the absorption or radiation of the light quantum (photon) when the electron is transition, respectively, to a higher or low level. The above-described behavior of electrons in a quantum point leads to a discrete energy spectrum uncharacteristic for macro objects, for which CT is often called artificial atoms in which the electron levels are discrete.

The strength (energy) of the connection holes and the electron determines the exciton radius, which is a characteristic value for each substance. If the particle size is less than the exciton radius, then the exciton is limited in the space by sizes, and the corresponding bond energy varies significantly compared with the volumetric substance (see "Quantum-based effect"). It is not difficult to guess that if the energy of the exciton changes, the energy of a photon emitted by the system changes during the transition of an excited electron to its original place. Thus, obtaining monodisperse colloidal solutions of nanoparticles of various sizes, you can control the transition energies in a wide range of optical spectrum.

The first quantum dots were metal nanoparticles that were synthesized in ancient Egypt for dyeing various glasses (by the way, the Kremlin's rubble stars were obtained along the close technology), although the substrates are grown on the substrates of GAN semiconductor particles and colloidal solutions of CDSE nanocrystals. At the moment, many ways to obtain quantum points are known, for example, they can be "cut" from thin layers of semiconductor "heterostructures" using "nanolithography", and it is possible to spontaneously form in the form of nano-dimensional inclusions of the structures of the semiconductor material of the same type in the matrix of the other. The method of "molecular-beam epitaxy" with a significant difference in the parameters of the elementary cell of the substrate and the sprayed layer can be achieved on the substrate of pyramidal quantum dots, for the study of the properties of which the Nobel Prize was awarded to the Academician J.I. Alferov. Controlling the conditions for the synthesis processes, theoretically, you can get quantum points of certain sizes with specified properties.

Quantum dots are still a "young" object of the study, but wide prospects for their use for the design of lasers and new generation displays are already quite obvious. The optical properties of the CT are used in the most unexpected areas of science that require the rebuilt fluorescent properties of the material, for example, in medical studies with their help it turns out to be able to "highlight" patients with tissue. People who dream of "quantum computers" see in quantum points of promising candidates for building qubits.

Literature

N. Kobayashi. Introduction to Nanotechnology. M.: Binin. Laboratory of Knowledge, 2007, 134 p.

V.Ya. Demikhovsky, G.A. Vugalter physics of quantum low-dimensional structures. M.: Logos, 2000.

Numerous spectroscopic methods that appeared in the second half of the 20th century - electronic and atomic-power microscopy, nuclear magnetic resonance spectroscopy, mass spectrometry - seemingly sent a traditional optical microscopy "retirement". However, the skillful use of the fluorescence phenomenon more than once extended the "veteran" life. This article will talk about quantum Points (Fluorescent semiconductor nanocrystals), inspiring new forces into optical microscopy and allowed to look at the notorious diffraction limit. The unique physical properties of quantum points make them an ideal means for supersensitive multicolor registration of biological objects, as well as for medical diagnostics.

The paper presents ideas about the physical principles that determine the unique properties of quantum points, basic ideas and prospects for using nanocrystals and is described about the successes of their use in biology and medicine. The article is based on the results of studies conducted in recent years in the Laboratory of Molecular Biophysics Institute of Bioorganic Chemistry. MM Shemyakina and Yu.A. Ovchinnikova, together with the University of Reimary and the Belarusian State University, aimed at developing new generation biomarkers for various areas of clinical diagnosis, including cancer and autoimmune diseases, as well as to create new types of nanosensors for simultaneous registration of many biomedical parameters. The initial version of the work was published in "Nature"; To some extent, the article is based on the second seminar of the Council of Young Scientists IBH RAS. - Ed.

Part I, Theoretical

Figure 1. Discrete energy levels in nanocrystals. "Solid" semiconductor ( left) has a valence zone and conduction zone, separated by a prohibited zone E G.. Nanocrystal from the semiconductor ( on right) It is characterized by discrete energy levels similar to the level of energy of a single atom. In nanocrimistal E G. It is a size function: an increase in the size of the nanocrystal leads to a decrease E G..

A decrease in the particle size leads to the manifestation of the very unusual properties of the material from which it is made. The reason for this is the quantum-mechanical effects arising from the spatial limitation of the movement of charge carriers: the energy of the carriers in this case becomes discrete. And the number of energy levels, as the quantum mechanic teaches, depends on the size of the "potential pit", the height of the potential barrier and the mass of the charge carrier. The increase in the size of the "pit" leads to an increase in the number of energy levels, which are becoming closer to each other, until they are alive, and the energy spectrum will not become "solid" (Fig. 1). Limit the movement of charge carriers in one coordinate (forming quantum films), along two coordinates (quantum wires or threads) or for all three directions - it will be quantum Points (CT).

Semiconductor nanocrystals are intermediate structures between molecular clusters and "solid" materials. The boundaries between molecular, nanocrystalline and solid materials are not defined with sufficient clarity; However, the range of 100 ÷ 10,000 atoms on a particle can be approximately considered the "upper limit" of nanocrystals. The upper limit corresponds to the dimensions for which the interval between energy levels exceeds the energy of thermal fluctuations kt. (k. - Permanent Boltzmann, T. - Temperature) when charge carriers become mobile.

The natural scale of the length for electronic excited areas in "continuous" semiconductors is determined by the radius of the exciton of boron a X.which depends on the strength of the Coulomb interaction between the electron ( e.) I. hole (h.). In nanocrystals of the same order a X size itself Begins to influence the configuration of the couple e-H. And, therefore, the size of the exciton. It turns out that in this case the electronic energies are directly determined by the size of the nanocrystal - this phenomenon is known as the "effect of a quantum restriction". Using this effect, you can adjust the width of the nanocrystal zone ( E G.), Just changing the particle size (Table 1).

Unique properties of quantum dots

As a physical object, quantum dots are known for quite a long time, being one of the intensively developing forms today heterostructures . A feature of quantum dots in the form of colloidal nanocrystals is that each point is an isolated and mobile object located in a solvent. Such nanocrystals can be used to build various associates, hybrids, ordered layers, etc., on the basis of which elements of electronic and optoelectronic devices, probes and sensors for analyzes in micro-volumes of the substance, various fluorescent, chemiluminescent and photoelectrochemical nano-sized sensors are constructed.

The cause of the rapid penetration of semiconductor nanocrystals in a variety of science and technology areas are their unique optical characteristics,:

  • a narrow symmetric peak of fluorescence (in contrast to organic dyes, for which the presence of a long-wave "tail"; Fig. 2, left), the position of which is regulated by choosing the size of the nanocrystal and its composition (Fig. 3);
  • wide excitation strip, which allows the excitation of nanocrystals of different colors with one source of radiation (Fig. 2, left). This dignity is fundamentally when creating multicolor coding systems;
  • high fluorescence brightness, determined by the high extinction value and high quantum output (for CDSE / ZNS nanocrystals - up to 70%);
  • unique high photostability (Fig. 2, on right), which allows the use of high power excitation sources.

Figure 2. Spectral properties of cadmium selenium (CDSE) quantum dots. Left: Nanocrystals of different colors can be excited by one source (the arrow shows the excitation of an argon laser with a wavelength of 488 nm). On the inlet - fluorescence of CDSE / ZNS nanocrystals of different sizes (and, accordingly, colors), excited by one light source (UV lamp). On right: Quantum dots are extremely photobilized compared to other common dyes, quickly destroyed under the ray of mercury lamp in a fluorescent microscope.

Figure 3. Properties of quantum dots from different materials. From above: Fluorescence ranges of nanocrystals made from different materials. Bottom: CDSE Quantum points of different sizes cover the entire visible range of 460-660 nm. From the bottom to the right: The scheme of a stabilized quantum point, where the "kernel" is covered with a semiconductor shell and a protective layer of polymer.

Giving technology

The synthesis of nanocrystals is carried out by quick injection of precursor compounds into the reaction medium at high temperatures (300-350 ° C) and the subsequent slow growth of nanocrystals at a relatively low temperature (250-300 ° C). In the "focusing" mode of synthesis, the growth rate of small particles is greater than the growth rate of large, as a result of which the variation in the size of nanocrystals is reduced ,.

The technology of controlled synthesis allows you to control the form of nanoparticles using the anisotropy of nanocrystals. The characteristic crystal structure of a particular material (for example, for CDSe is characterized by hexagonal packaging - trocitis, Fig. 3) mediates "selected" growth directions that determine the form of nanocrystals. So the nanishing or tetrapeods are obtained - nanocrystals, elongated in four directions (Fig. 4).

Figure 4. Different shape of CDSE nanocrystals. Left: CDSE / ZNS spherical nanocrystals (quantum dots); in the center: rod-like shape (quantum rods). On right: In the form of tetrapeods. (Translucent electron microscopy. Tag - 20 nm.)

Persons on the path of practical application

On the path of practical use of nanocrystals from semiconductors of groups II-VI there is a number of restrictions. First, the luminescence quantum yield of them significantly depends on the properties of the environment. Secondly, the stability of the nuclei of nanocrystals in aqueous solutions is also small. The problem is superficial "defects", playing the role of non-violent recombination centers or "traps" for excited e-H. Couple.

To overcome these problems, quantum points conclude into a shell consisting of several layers of wide-resistant material. This allows you to isolate e-H. A couple in the kernel, to increase the time of her life, reduce the non-durable recombination, and therefore increase the quantum fluorescence yield and photostability.

In this regard, by now the most widely used fluorescent nanocrystals have the structure of the kernel / shell (Fig. 3). The developed procedures for the synthesis of CDSE / ZNS nanocrystals allow you to achieve a quantum output of 90%, which is close to the best organic fluorescent dyes.

Part II: The use of quoted dots in the form of colloidal nanocrystals

Fluorophores in medicine and biology

The unique properties of the CT allow them to use them in almost all systems of the labeling and visualization of biological objects (with the exception of only fluorescent intracellular labels expressed by genetically - well-known fluorescent proteins).

To visualize biological objects or CT processes, you can enter an object directly or with the "sewn" recognizing molecules (usually antibodies or oligonucleotides). Nanocrystals penetrate and distributed over the object according to their properties. For example, the nanocrystals of different sizes penetrate into the biological membranes in different ways, and since the size determines the color of fluorescence, different areas of the object are painted in different ways (Fig. 5) ,. The presence of recognizing molecules on the surface of the nanocrystals allows you to implement address binding: the desired object (for example, tumor) is painted in a specified color!

Figure 5. Coloring objects. Left: Multicolor confocal fluorescent image of the distribution of quantum dots against the background of the microstructure of the cell cytoskeleton and core in the cells of the THP-1 line of human phagocytes. Nanocrystals remain photostable in cells for at least 24 hours and do not cause violations of the structure and function of cells. On right: The accumulation of nanocrystals, "stitched" with a RGD peptide in the tumor area (arrow). To the right - control, nanocrystals are introduced without peptide (CDTE nanocrystals, 705 nm).

Spectral coding and "liquid microchips"

As already mentioned, the peak of fluorescence of narrow nanocrystals and is symmetrical, which allows you to securely allocate the fluorescence signal of different colors of different colors (up to ten colors in the visible range). On the contrary, the absorption band of nanocrystals is wide, that is, nanocrystals of all colors can be excited by a single light source. These properties, as well as their high photostability, make quantum dots ideal fluorophores for multicolor spectral encoding objects - like a bar code, but using multicolor and "invisible" codes that fluorescents in the infrared area.

Currently, the term "liquid microchips" is increasingly used, which allows, similar to classic flat chips, where detecting elements are located on the plane, analyzing the set of parameters at the same time using the sample microchlishes. The principle of spectral coding using liquid microchips illustrates Figure 6. Each element of the microchip contains the specified quantity of CT specific colors, and the number of encoded options can be very large!

Figure 6. The principle of spectral coding. Left: "Normal" flat microchip. On right: "Liquid microchip", each element of which contains the specified amounts of CT specific colors. For n. Fluorescence intensity levels and m. colors theoretical amount of encoded options is equal n M.-1. So, for 5-6 colors and 6 levels of intensity it will be 10,000-40000 options.

Such coded trace elements can be used for direct labeling of any objects (for example, securities). Being implemented in polymer matrices, they are extremely stable and durable. Another aspect of application is the identification of biological objects in the development of early diagnostic methods. The method of indication and identification is that a certain recognizing molecule is attached to each spectral coded element of the microchip. In the solution there is a second recognizing molecule to which the signal fluoroform "will be sewn". The simultaneous appearance of the fluorescence of the microchip and signal fluorophore indicates the presence of the object being studied in the analyzed mixture.

A flow cytometry can be used to analyze the coded microparticles "on the stream". A solution containing microparticles passes through a channel irradiated by a laser, where each particle is characterized by spectral. The software software allows you to identify and characterize events associated with the appearance of certain compounds in the sample - for example, cancer or autoimmune diseases ,.

In the future, on the basis of semiconductor fluorescent nanocrystals, microanalysts can be created for simultaneous registration at once a huge number of objects.

Molecular sensors

The use of CT as probes allows measuring the parameters of the medium in local areas, the size of which is comparable to the size of the probe (nanometer scale). The basis of such measuring instruments is based on the use of the Effect of Ferester Energy Resonant Raming (Förster Resonanse Energy Transfer - FRET). The essence of the Fret effect lies in the fact that when two objects (donor and acceptor) and overlapping fluorescence spectrum First S. spectrum of absorption The second, the energy is transmitted nonradiatively - and if the acceptor can fluorescence, it will light up with a double strength.

On the effect of FRET, we already wrote in the article " Roulette for spectroscopist » .

Three parameters of quantum points make them very attractive donors in systems with a FRET format.

  1. Ability to select the emission wavelength with high accuracy to obtain the maximum overlap of the emission spectra and acceptor excitation.
  2. The possibility of excitation of different CTs of one wavelength of one light source.
  3. The possibility of excitation in the spectral region is far from the wavelength of the emission (difference\u003e 100 nm).

There are two FRET effect strategies:

  • registration of an act of interaction between two molecules due to conformational changes in the donor-acceptor system and
  • registration of changes in the optical properties of the donor or acceptor (for example, absorption spectrum).

This approach made it possible to implement nanoscale sensors for measuring the pH and the concentration of metal ions in the local area of \u200b\u200bthe sample. The sensitive element in such a sensor is a layer of indicator molecules that change the optical properties when binding to a registered ion. As a result of the binding, the overlap of the fluorescence spectra of the CT and the absorption of the indicator changes, which changes the efficiency of energy transmission.

The approach that uses conformational changes in the system donor-acceptor is implemented in a nanoscale temperature sensor. The sensor action is based on the temperature change of the shape of the polymer molecule connecting the quantum point and the acceptor - the fluorescence steer. When the temperature changes, the distance between the stewer and fluorofeof changes, and the intensity of fluorescence, for which the conclusion is already made.

Molecular diagnosis

The gap or formation of communication between the donor and the acceptor can be registered in the same way. Figure 7 shows the "sandwich" principle of registration, in which the recorded object acts as a binder ("adapter") between the donor and the acceptor.

Figure 7. Registration principle using Fret-format. The formation of a conjugate ("Liquid Microchip") - (registered object) - (signal fluorophore) leads to a rapprochement of the donor (nanocrystal) with an acceptor (ALEXAFLUOR dye). In itself, laser radiation does not excite the fluorescence of the dye; The fluorescent signal appears only due to the resonant transfer of energy from the CDSE / ZNS nanocrystal. Left: Conjugate structure with energy transfer. On right: Spectral diagram of excitation of the dye.

An example of the implementation of this method is to create a diagnosis for an autoimmune disease. systemic sclerodermia (scleroderma). Here, the donor was quantum dots with a fluorescence wavelength of 590 nm, and the acceptor is an organic dye - AlexaFluor 633. On the surface of the microparticle containing quantum dots, "sewed" an antigen to the autoantibore - marker scleroderma. In the solution was administered secondary antibodies marked with dye. In the absence of a target, the dye is not closer to the surface of the microparticle, the transfer of energy is missing and the dye is not fluorescents. But if autoantibodies appear in the sample, this leads to the formation of a microparticle-autoantile-dye complex. As a result of the transfer of energy, the dye is excited, and the signal of its fluorescence with a wavelength of 633 nm appears in the spectrum.

The importance of this work is also in the fact that autoantibodies can be used as diagnostic markers at the earliest stage of the development of autoimmune diseases. "Liquid microchips" allow you to create test systems in which antigens are in much more natural conditions rather than on the plane (as in the "ordinary" microchips). The results obtained open the way to create a new type of clinical diagnostic tests based on the use of quantum dots. And the implementation of approaches based on the use of spectral coded liquid microchips will simultaneously determine the content of a multitude of markers at once, which is the basis of a significant increase in the reliability of the results of the diagnosis and development of early diagnostic methods.

Hybrid molecular devices

The possibility of flexible control of spectral characteristics of quantum dots opens the path to nanoscale spectral devices. In particular, CD based on Cadmium Tellur (CDTE) allowed to expand spectral sensitivity bacteroriodopsin (BR), known for its ability to use light energy for "pumping" protons through the membrane. (The resulting electrochemical gradient is used by bacteria for ATP synthesis.)

In fact, a new hybrid material was obtained: joining quantum dots to purple membrane - Lipid membrane containing tightly packed bacterioric molecules - expands the range of photosensitivity to UV and blue spectrum areas, where the "ordinary" BR does not absorb light (Fig. 8). The energy transmission mechanism is bacterioropping from a quantum point absorbing light in UV and blue areas, all the same: it is Fret; The resulting radiation in this case protrudes retinal - The same pigment that works in the photoreceptor Rhodopsin.

Figure 8. "Upgrade" of bacterioroppens with quantum dots. Left: A proteolyposome containing bacterioriodopsin (in the form of trimers) with "crawls" to it by CDTE-based quantum dots (shown by orange spheres). On right: Expansion scheme of the spectral sensitivity of the BR due to CT: on the spectrum area observations CT is in the UV and blue parts of the spectrum; spectrum empty You can "configure", pick up the size of the nanocrystal. However, in this system, the energy emission system does not occur by quantum dots: the energy itself migrates to the bacterioriodopsin, which makes a job (pumps H + ions inside the liposome).

Created on the basis of such a material of proteolyposomes (lipid "bubbles" containing the BR-CT hybrid) during lighting is injected into the protons, effectively lowering the pH (Fig. 8). This insignificant invention may lie down in the future as a basis for optoelectronic and photonic devices and find use in the field of electric power industry and other types of photovoltaic transformations.

Summarizing, it should be emphasized that quoted dots in the form of colloidal nanocrystals are promising objects of nano-, bionano- and biomedanological technologies. After the first demonstration of the possibilities of quantum points as fluorophores in 1998, for several years, a lull was observed associated with the formation of new original approaches to the use of nanocrystals and the implementation of the potential capabilities that these unique objects possess. But in recent years there has been a sharp rise: the accumulation of ideas and their implementations identified a breakthrough in the field of creating new devices and tools based on the use of semiconductor nanocrystalline quantum dots in biology, medicine, electronic technology, technology of solar energy and many others. Of course, there are still many unsolved problems on this path, but growing interest, the growing number of teams that work on these problems, the growing number of publications on this area, suggest that quantum points will be the basis of the technique and the following generation technologies.

Video recording of speeches V.A. Oleinikova At the second seminar of the Council of Young Scientists IBH RAS, held on May 17, 2012.

Literature

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  7. Fluorescent Nobel Prize in Chemistry;
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  9. Yvonne Williams, Alyona Sukhanova, Maå,gorzata Nowostawska, Anthony M. Davies, Siobhan Mitchell, ET. Al .. (2009). PROBING CELL-TYPE-SPECIFIC INTRACELLULAR NANOSCALE BARRIERS USING SIZE-TUNED QUANTUM DOTS Nano-PH meter;
  10. Alyona Sukhanova, Andrei S. Susha, Alpan Bek, Sergiy Mayilo, Andrey L. Rogach, ET. Al .. (2007). Nanocrystal-Encoded Fluorescent Microbeads for Proteomics: Antibody Profiling and Diagnostics of Autoimmune Diseases. Nano Lett.. 7 , 2322-2327;
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Good time of day, habrarites! I think many noticed that advertising on displays based on quantum dots based on quantum dots, the so-called QD - LED (QLED) appear, and despite the fact that at the moment it is only marketing. Similarly, LED TV and Retina is the LCD display technology that uses LEDs based on quantum dots.

Your humble servant decided to still figure out what quantum dots and what they eat.

Instead of administration

Quantum - Fragment of the conductor or semiconductor, charge carriers (electrons or holes) of which are limited in space for all three measurements. The size of the quantum point should be so small that the quantum effects are essential. This is achieved if the kinetic electron energy is noticeably more than all other energy scales: primarily larger than the temperature expressed in the energy units. Quantum dots were first synthesized in the early 1980s by Alexei Ekimov in a glass matrix and Louis E. Bar in colloidal solutions. The term "quantum point" was proposed by Mark Reed.

The energy spectrum of the quantum point is discretened, and the distance between the stationary levels of the energy of the charge carrier depends on the size of the quantum point itself as - H / (2md ^ 2), where:

  1. h - the reduced plank permanent;
  2. d - characteristic point size;
  3. m - Effective electron mass at point
If we say a simple language, the quantum point is a semiconductor, the electrical characteristics of which depend on its size and shape.


For example, when switching an electron to the energy level below, a photon is emitted; Since you can adjust the size of the quantum point, you can change the energy of the photon emitted, and therefore changes the color of the emitted by the quantum point of light.

Types of quantum dot

Distinguish two types:
  • epitaxial quantum dots;
  • colloid quantum dots.
In essence, they are named according to the methods of their receipt. In detail to talk about them, I will not be due to a large number of chemical terms (Google to help). I will only add that with the help of colloidal synthesis, you can get nanocrystals coated with a layer of adsorbed surfactant molecules. Thus, they are soluble in organic solvents, after a modification - also in polar solvents.

Construction of quantum dot

Typically, a quantum point is a semiconductor crystal, in which quantum effects are implemented. The electron in such a crystal feels like a three-dimensional potential pit and has many stationary energy levels. Accordingly, when switching from one level on another quantum dot can emit a photon. With all the transitions, it is easy to control the changing crystal dimensions. It is also possible to transfer an electron to a high energy level and receive radiation from the transition between lower-way levels and as a result we obtain luminescence. Actually, it is the observation of this phenomenon that served as the first observation of quantum dots.

Now about displays

The story of full displays began in February 2011, when Samsung Electronics presented the development of a full-color display based on QLED quantum dots. It was a 4-inch display controlled by an active matrix, i.e. Each color pixel with a quantum dot can be turned on and off with a thin-film transistor.

To create a prototype on a flint fee, a layer of a solution of quantum dots is applied and the solvent is sprayed. After that, the rubber stamp with a comb surface is compressed in the quantum dot layer, it is separated and stamps on glass or flexible plastic. This is how the strips of quantum dots on the substrate are carried out. In color displays, each pixel contains red, green or blue subpixel. Accordingly, these colors are used with different intensity to obtain as much as possible shades.

The next step in the development was the publication of the article by scientists from the Indian Institute of Science in Bangalore. Where quantum points were described that luminescent not only orange, but also in the range from dark green to red.

What is the LCD worse?

The main difference between the QLED display from the LCD is that the second can cover only 20-30% of the color range. Also in QLED TVs, there is no need to use a layer with light filters, since the crystals when supplying voltages to them emit light always with a clearly defined wavelength and as a result with the same color value.


There were also news about the sale of a computer display on quantum dots in China. Unfortunately, to check out, in contrast to the TV I have not had the opportunity.

P.S. It is worth noting that the scope of the quantum dots is not limited to LED - monitors, among other things they can be used in field transistors, photocells, laser diodes, and the study of the ability to use them in medicine and quantum calculations.

P.P.S. If we talk about my personal opinion, then I think that they will not use the nearest tens of years, not because there are little known, and therefore, as prices for these displays are translated, but still want to hope that quantum Points will find their use in medicine, and will be used not only to increase profits, but also in good use.

Quantum Points - These are tiny crystals emitting light with precisely adjustable color value. Quantum Dot LED technology significantly improves image quality without affecting the final cost of devices, in theory :).

Conventional liquid crystal TVs can cover only 20-30% of the color range, which is capable of perceiving the human eye. The image on has great realism, but this technology is not focused on the mass production of large diagonals of displays. Who follows the market of TV, remembers that in early 2013, Sony introduced the first quantum Dot LED TV (Quantum Dot LED, QLED). Large TV manufacturers will release models of televisions on quantum points this year, Samsung has already presented them in Russia called Suhd, but about it at the end of the article. Let's find out what the displays produced by QLED technology differ from the already familiar LCD TVs.

In LCD TVs no clean colors

After all, liquid crystal displays consist of 5 layers: the source is the white light emitted by LEDs, which passes through several polarization filters. Filters, located in front and rear, combined with liquid crystals control the passing light stream, lowering or increasing its brightness. This is due to the transistors of pixels affecting the amount of light passing through the light filters (red, green, blue). The formed color of these three subpixels to which filters are applied, gives a specific color value of the pixel. Mixing colors occurs pretty "smoothly", but it is impossible to obtain clean red, green or blue simply. The stumbling block protrude filters that passes not one wave of a certain length, and a number of different wavelengths. For example, orange light also passes through the red light filter.

The LED emits the light when the voltages are submitted. Due to this, the electrons (E) are transmitted from the N-type material into the P-type material. The N-type material contains atoms with excess electrons. In the P-type material, there are atoms that lack electrons. If you get into the last excess electrons, they give energy in the form of light. In the usual semiconductor crystal, this is usually white light formed by a variety of waves of different lengths. The reason for this lies in the fact that electrons can be located at various energy levels. As a result, the obtained photons (P) have different energy, which is expressed in different lengths of radiation waves.

Stabilization of light by quantum dots

IN tVs QLED As a source of light, quantum dots act - these are crystals with a size of only a few nanometers. At the same time, the need for a layer with light filters disappears, because when the crystals are submitted, the light is always emitted with a clearly defined wavelength, and hence the color value. This effect is achieved by meager sizes of a quantum point, in which an electron, as in the atom, is able to move only in a limited space. As in the atom, the electron of the quantum point may occupy only strictly defined energy levels. Due to the fact that these energy levels depend on the material, the possibility of targeted setting up the optical properties of quantum dots appears. For example, to obtain a red color, crystals are used from cadmium alloy, zinc and selenium (CDZNSE), the dimensions of which are about 10-12 nm. The fusion of cadmium and selenium is suitable for yellow, green and blue colors, the latter can also be obtained using nanocrystals from a zinc and sulfur compound of 2-3 nm.

Mass production of blue crystals is very complex and costly, therefore, submitted in 2013 by Sony Sony TV is not a "thoroughbred" QLED TV based on quantum dots. In the rear part of their displays, the layer of blue LEDs is located, the light of which passes through the layer of red and green nanocrystals. As a result, they are essentially replacing the frequent filters currently. Thanks to this, the color coverage in comparison with ordinary LCD TVs increases by 50%, but does not reach the level of the "pure" QLED screen. The latter in addition to wider color coverage have another advantage: they allow saving energy, since the need for layer with light filters disappears. Thanks to this, the front of the screen in QLED TVs also gets more light than in ordinary TVs that skip only about 5% of the light flux.

QLED TV with display based on Samsung quantum dots

SAMSUNG Electronics has presented premium TVs in Russia, manufactured by quantum dot technology. NEWs with a resolution of 3840 × 2160 pixels were not cheap, and the flagship model was at all estimated at 2 million rubles.

Innovations. SAMSUNG SUHD curved TVs on quantum dots differ from common LCD models with higher color rendering characteristics, contrast and power consumption. The integrated image processing processor SUHD REMASTERING ENGINE allows you to scale the low-resolution video content in 4K. In addition, new televisions have received the functions of the intellectual illumination of Peak Illuminator and Precision Black, Nano Crystal Color technology (improves colors and naturalness), UHD Dimming (provides optimal contrast) and Auto Depth Enhancer (automatic adjustment of contrast for certain areas of the picture). The software basis of the TVs is the Tizen operating system with the updated SAMSUNG SMART TV platform.

Prices. The Samsung SUHD TV family is presented in three series (JS9500, JS9000 and JS8500), where cost begins with 130 thousand rubles. In so many Russian buyers will cost a 48-inch model UE48JS8500TXRU. The maximum price of a TV with quantum dots reaches 2 million rubles - for the UE88JS9500TXRU model with an 88-inch curved display.

TVs of the new generation using QLED technology are preparing South Korean Samsung Electronics and LG Electronics, Chinese TCL and Hisense, as well as Japanese Sony. The latter has already released LCD-TVs manufactured using quantum dot technology, which I mentioned in the description of the Quantum Dot LED technology.