The cutting-edge technology of quantum dots has emerged as a ray of hope in the never-ending search for better cancer detection techniques. These small semiconductor particles are transforming the way we locate and monitor cancer cells inside the human body because of their exceptional capacity to emit exact wavelengths of light. This article explores the creative uses of quantum dots that are quickly changing the field of cancer detection by providing unmatched accuracy, sensitivity, and the potential for early diagnosis.
Wait – what exactly is this technology?
This technology, recently brought to light by chemists Moungi Bawendi and Louis Brus and physicist Alexei Ekimov [1], is known as quantum dots. But what exactly are quantum dots? Simply put, quantum dots refer to nanoparticles, which are roughly a few billionths of a meter in diameter and can cater to different, specific needs due to their great adjustability, being able to modify characteristics such as color, size, and shape. [1].
More specifically, quantum dots work primarily by changing their size. When you change the size of a quantum dot to be smaller or larger, the color changes in accordance with that size. The smaller the dot, the more compressed the waves become, and the more blue the dots appear. On the contrary, the larger the dot, the more expanded the waves become, which causes less energy to be concentrated in any one area of the dot. This results in the dot having more of a red appearance [1].
While the idea of these nanoparticles and their applications might be new, the actual concept of quantum dots, along with their high adjustability and potential usefulness in so many different areas, is not new. In fact, nearly a century ago, scientists theorized that the existence of quantum dots, or rather, something with easily modifiable, versatile properties that could adapt to different purposes, was possible [1]. At the time, though, it seemed nearly impossible to actually make this concept a reality. To make one quantum dot, scientists would need to obtain a perfectly crystalline – or perfectly geometrically aligned – material, which, on its own, was not nearly possible to fabricate back then. But not just that; they’d also need to figure out some way to very precisely sculpt the particle, formulating atom layer after atom layer with the utmost geometrical symmetricality and precision down to the nanometer. As you probably figured out by now, there was no way scientists from the Roaring 20’s were going to go out of their way to try and pull that much off.
How were quantum dots turned into a reality?
Although yes, it was difficult to even conceptualize, let alone create anything relatively as precise and powerful as quantum dots required themselves to be, a pair of two particular scientists managed to fight through the adversity and create the first quantum dots.
In the early 1980s, scientists Louis Brus and Alexei Ekimov proved to everyone that it could actually be done. Ekimov, deciding to take on this challenge, used a glass prototype to see if his method was possible. He added copper chloride, a highly corrosive compound, to the glass, which broke microscopic crystals of different sizes off the glass. When he analyzed some patterns he saw, he realized that the color of the glass had a direct correlation to the size. In other words, the larger crystal appeared to be more red, while the smaller crystals appeared to be more blue. And to say that this discovery was major would be a massive understatement.
Brus, noticing Ekimov’s observations, decided to extend his findings further and truly test the limits of the newborn technology. After creating microscopic glass crystals with the copper chloride, Brus placed the crystals within a saltwater solution to see if the particles would retain their color-related properties. And despite his resounding doubts, the crystals retained their varied colorful appearances. Surprised, Brus decided to persevere with his discoveries. Placing the crystals in hydrofluoric acid, which is known to corrode strong metals, he had every single intention that the crystals would break down. To his surprise, the crystals kept their properties: the smaller crystals were blue and larger crystals were red.
As the concept of quantum dots started to surface in the biochemistry department, Moungi Bawendi of the Massachusetts Institute of Technology started to make leaps and bounds into what we know as quantum dots today. After countless hours of research, Bawendi was able to come up with a method by which he could control the size of these quantum dots. The first step of controlling sizes was to inject an agent into a chemical solution that would instantly form microscopically small, scattered in size, crystals. Then, by promptly adjusting the temperature of the solution, he could either accelerate or instantly stop the growth of these crystals. The implications of Bawendi’s findings were massive – he essentially derived a method by which he could improve the versatility of the already flexible particles – and this newfound method opened so many doors in which the dots could be put to use.
What are some applications of these dots?
As you probably could’ve guessed, these new, extremely versatile quantum dots have a large number of applications. For example, quantum dots make it possible to precisely change the color of LED lights by modifying their color through the size of the quantum dots. By using these newfound dots in various LED applications, the overall efficiency of the products can be improved by up to three times.
The implications of this increased efficiency are massive. For starters, you can produce LED products with a wider color range and accuracy [1]. Although the initial price of installing LED with quantum dots might be slightly more expensive, research has proven that LED products that are enhanced with quantum dots have an increased lifespan, so this initial “breaking of the bank” that comes with quantum dot-enhanced LED products will quickly break even.
Where does detecting cancer come into the equation?
When pondering over the possibility of these semiconductor particles’ usefulness in detecting cancer, one must first understand what components of the dots make them useful biosensors. When quantum dots come into contact with specific biomolecules, their fluorescence changes! This, in particular, is useful in the field of cancer because cancerous growths and tumors have biomolecules (like various proteins, nucleic acids, hormones, and immune-triggering antigens) [2] that are specific to cancer. And if you recognize patterns of dot fluorescence in relation to specific biomolecules they are in contact with, you can begin to visualize how these could be useful for cancer detection in general.
When scanning for cancer, doctors need to emit light at very specific wavelengths in order to mark potentially cancerous developments [2]. Due to the nature of the scanning, the range of frequencies where the tumor becomes visible is very narrow when using normal scanning technology like MRIs. However, the advent of quantum dots can fix just that issue – since these dots are extremely adjustable and their properties (namely, their color) changes in correspondence with their size, doctors trying to scan for cancerous developments can manipulate the characteristics of these dots in order to emit certain light wavelengths, which can prospectively allow cancerous developments to be detected early on in potential cancer patients.
The possibilities for early detection that quantum dots bring to the table is specifically important for preventing the development of cancer. When doctors locate benign abnormal growths in patients, they can administer treatment in them through means of chemotherapy, radiation therapy, medications, and others. This effectively allows them to get rid of growth before it develops into the likes of something far worse [2].
But that’s not all. While yes, quantum dots can be useful for detecting cancer growths early on in patients, they have an even greater potential. By surrounding an early-stage cancerous growth with these particles, the behavior and response to treatment of the aforementioned growths can be tracked over a period of time. This information, which would otherwise be nearly impossible to successfully obtain, is crucial in understanding the dynamics of different cancers. It would allow scientists to not only research many types of cancer, but also to develop biomedical solutions and non-intervention-heavy treatments for them.
But we already have solid scanning systems in place – Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scans, just to name a few. And just because we are on the verge of finding novel technology doesn’t mean we can abandon what already works, right? Absolutely. And what’s better is that quantum dots can allow us to not only maintain our current scanning systems, but actually improve them. As previously mentioned, quantum dots enhance the quality and accuracy of different colors in LED and imaging technologies. This wide range of capability can be used in MRI and CT scan machines as contrast agents, which will provide more sharp distinctions between different colors on the scans. Due to the dots’ high X-ray absorption properties, CT scans will have enhanced contrast and sharper imaging, which can then be used to improve the visualization of different anatomical structures [1]. This improved all-round distinction will aid doctors in diagnoses, allowing human error to interfere less with the health of those who are in need of accurate and precise medical attention.
So what’s holding us back from employing these dots now?
While the prospects of the future seem great with the rise of quantum dots, new cancer imaging, and the possible improvements in the medical field, there are a few key factors that are currently preventing humans as a society from progressing forward with it.
The first struggle with these nanoparticles is – you guessed it – monetary costs. With the current rendition of quantum dots, the cost for one cubic foot worth of solvent and solute that will create the particles is approximately one hundred dollars. This is extremely expensive, especially when compared to the price of MRI and CT scanning material, which comes out to be around five dollars for the same amount of material [3]. Given the huge price difference, one can only imagine the costs of these dots if they were to be implemented on a widespread basis.
The second of the primary struggles that come with these dots actually lies in safety itself. The majority of these particles are being created by large private figureheads [4], which means that the government and its organizations (particularly the FDA) can’t necessarily get a hold on them. Because of this, the FDA cannot possibly determine how these particles adhere to its safety standards [4], which means they can’t be legally commercially used. But illegally..? (Just kidding, of course).
But we shouldn’t let the small number of setbacks stop us from visualizing the end goal and the potential that quantum dots have in store for society as a whole. And at the moment, intensive research has started in this field to try and make the dots as safe, economically viable, and publicly streamlined as possible. So who knows? Only time will tell if you wake up one day and see a huge headline on the news saying that quantum dots have struck it big.
Bibliography
- Gramling, Carolyn. The Development of Quantum Dots Wins the 2023 Nobel Prize in Chemistry. 4 Oct. 2023, www.sciencenews.org/article/quantum-dots-nanoparticles-bawendi-brus-ekimov.
- “What Is Stage 1 Cancer & How Is Stage 1 Cancer Treated?” Cancer Treatment Centers of America, 18 Feb. 2019, www.cancercenter.com/stage-one-cancer.
- John Fitzgerald Weaver. “For $10, Quantum Dots Change the Color of Light and Lower the Cost of Solar Electricity 34%.” Electrek, 5 Jan. 2018, electrek.co/2018/01/05/quantum-dots-lower-cost-of-solar-electricity/.
- Gidwani, Bina, et al. “Quantum Dots: Prospectives, Toxicity, Advances and Applications.” Journal of Drug Delivery Science and Technology, vol. 61, Feb. 2021, p. 102308, https://doi.org/10.1016/j.jddst.2020.102308.