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The Fantastic Journey of Quantum Dots: How to Work Magic in Biomedicine?
Quantum dots (QDs) are semiconductor nanoparticles with a diameter less than 10 nanometers that exhibit size-dependent properties, especially in optical absorption and photoluminescence. Depending on their diameter, the fluorescence emission peak of QDs can be tuned, making them versatile probes and markers in the biomedical field. The QDs currently on the market are mainly made of materials containing cadmium (Cd), which makes their application in vivo full of challenges and controversy, because Cd2+ sodium ions are highly toxic to cells and tissues. toxicity.
Due to concerns about potential toxicity to the biological environment, researchers have gradually turned to the development of cadmium-free quantum dots (CFQDs) to improve their safety in biomedical applications.
The new generation of CFQDs such as ZnS/ZnSe QDs, graphene QDs, and silicon QDs exhibit low toxicity and good colloidal and photoluminescent stability, and are suitable for in vitro and in vivo models. QDs functionalized with DNA or peptides are widely used, mainly for targeted imaging of cells and tissues and monitoring of drug delivery. For example, a variety of techniques can be used to image Cd-free QDs, including confocal/multiphoton microscopy and CARS imaging. These techniques allow researchers to observe cells and tissue structures with higher resolution and in a more biocompatible way.
These QDs also have the flexibility to be complexed with other reagents such as metal nanoparticles, radiolabels, and Raman tags, enabling multimodal imaging via multifunctional nanolabeling based on cadmium-free QDs.
The cadmium-free quantum dot design is not limited to imaging, but can also be used as a platform for non-invasive therapeutics and diagnostics, known as theranostics. Recently, cadmium-free quantum dots have also shown great potential in the manufacture of next-generation solar cells and displays.
In the field of materials science, the research enthusiasm for quantum dots continues to grow. The properties of these nanoparticles can be manipulated and tested for their applications to further understand their behavior, but most QDs are made from toxic heavy metals, which limits their use in biological systems, and consumers are reluctant to buy products containing toxic heavy metals. Metal products are also at risk.
This has prompted researchers to develop quantum dots that do not contain heavy metals, such as cadmium-free quantum dots, to address this issue.
Advances in the medical field have been explored for decades in an attempt to gain knowledge about unknown diseases such as cancer. Although chemotherapy remains one of the mainstream treatments, the movement of its toxic chemicals in the body poses considerable risks. At this point, the potential of cadmium-free quantum dots emerges.
Michael Sailor and his team at the University of California, San Diego have developed the first cadmium-free nanoscale quantum dots that emit intense light, allowing doctors to examine internal organs and release cancer drugs before poisons degrade into harmless byproducts. . This silicon wafer-based design can form silicic acid needed by the body after degradation, which helps normal bone and tissue growth.
Application Cases
Zinc Sulfur Quantum Dots
As a new material to replace cadmium-grade quantum dots, zinc-sulfur quantum dots (ZnS QDs) have shown many interesting applications in biomedical research, such as detecting food toxins, such as the harmful aflatoxin B1, which causes The damage to human health cannot be underestimated.
Indium Quantum Dots
Another type of quantum dots that do not contain heavy metals are indium-based quantum dots, especially CuInS2 quantum dots, which are used as luminescent markers and can emit light in the near-infrared region. The stability, low toxicity, and high quantum yield of these quantum dots make them show considerable promise in cancer drug delivery and imaging.
Silicon Quantum Dots
Finally, silicon quantum dots are also beginning to show their potential in optoelectronic and biological applications. These quantum dots can be used in photochemical applications and biological detection, proving their application value in detecting formaldehyde in water.
As scientists gain a deeper understanding of quantum dots, we are excited about the changes they may bring to future biomedicine and materials science. Will this change the way we think about disease treatment and detection?
