Quantum Dots——A Definition, How They Work, Manufacturing, Applications and Their Use In Fighting Cancer
1 Background
Quantum dots are tiny nanocrystals that glow when stimulated by an external light source, such as ultraviolet light. How many atoms are contained in the dots determines their size, and the size of the dots determines the color of the light emitted.
1.1 Quantum Dot Materials
Quantum dots can be made from a range of materials, the most commonly used currently include zinc sulfide, lead sulfide, cadmium selenide and indium phosphide. Many of the cutting-edge applications of quantum dots are in the human body. They are also coated with a protective polymer to avoid leaching of toxic substances from the QDS.
1.2 How Quantum Dots Work
When energy is applied to an atom, electrons are excited and transferred to higher energy levels. This additional energy is emitted in the form of light corresponding to a specific frequency as the electron returns to the lower steady state. Quantum dots work in much the same way, but the crystal behaves like a very large atom, and the source of energy used to stimulate the dots is usually ultraviolet light. The frequency or color of the emitted light is not related to the material used in the quantum dot, but is determined by the size of the quantum dot.
1.3 Quantum Dot Size and Colour Relationship
Larger QDS produce light with longer wavelengths, while smaller QDS produce light with shorter wavelengths. In terms of colors in the visible spectrum, this means that large QDS produce red light and small QDS produce blue light -sizes in between can produce all colors in the spectrum. By combining QDS of different sizes in the same sample, the entire spectrum can be generated simultaneously and appears as white light.
1.4 Manufacturing Methods
Quantum dots can be made by various processes such as colloid synthesis, chemical vapor deposition (CVD), and the easiest way to obtain them is through benchtop colloid synthesis. Electrochemical techniques and CVD can be used to create ordered QDS arrays on substrate materials.
2 Applications
From high-resolution TV screens and home lighting to future quantum computers and medical applications, quantum dots could have a wide range of applications.
2.1 Medical Applications and Cancer Treatments
Quantum dots can be wrapped in a shell to mimic organic receptors in the body. These receptors can correspond to specific diseases, viruses, or other substances. The quantum dot will then seek and attach to the disease site. Due to the fluorescent nature of QDS, the problematic location points can be easily detected. The small number of receptors needed on the surface compared to the surface area of the site itself leaves plenty of room for other useful components, including drugs that quantum dots have been seeking to treat various diseases.
In this way, QDS can be tuned to look for cancer cells and deliver chemotherapy drugs directly to them. This avoids poisoning healthy cells and therefore avoids many of the side effects associated with cancer treatment.
2.2 Lighting Applications
The energy emitted by QDS, in the form of light, is close to 100% of the energy input to the system, and this unusually efficient efficiency gives QDS a powerful advantage as individual color pixels in light and bright color flat panel displays. For illumination, a quantum dot layer could be sandwicsandwiced between two conductive layers, and an electric current directly applied to the dots between these layers would make them fluorescent, making it a very efficient light source.