Heavy-Metal Quantum Dots

(NHI Nanoblog) Glowing, ultra-tiny particles known as quantum dots excite researchers and industry for a good reason: They may be groundbreaking for a wide variety of products, from medical sensors to televisions.

But the composition of the dots, which when excited emit light of different colors depending on their size, concerns the very people who are pushing them. Most quantum dots are made primarily of a nanoscale version of the heavy metal cadmium, which is highly toxic.

A group of researchers, including one at the University at Buffalo, recently published some potentially encouraging results for quantum dot backers: In a 90-day study, monkeys injected with the cadmium selenide dots showed minimal effects from the substance. Two monkeys kept alive for follow-up study suffered no ill effects after a year.

The results were published online in the journal Nature Nanotechnology.

However, the news comes with a big caveat: Most of the cadmium remained in the liver, spleen and kidneys of the monkeys after the three months. That, the researchers write, implies there may be longer-term issues with getting the dots to clear the body — a crucial question for whether these particles are viable for medical uses .

Answering that question requires longer-horizon experiments, they write. But these initial findings suggest that short-term medical uses might be safe.

Nanotechnology is a broad term that encompasses a wide variety of uses of very small materials (a nanometer is a billionth of a meter). These substances can make better batteries or lighter and stronger bike frames, as well as new medical instruments and medicines that can save lives. They’re increasingly common in consumer products, from sunscreens to stain-repellent pants to boat paints that resist algae growth.

Nanomaterials are believed to hold great promise for a wide variety of applications. Their ultra-tiny size often gives them different properties, which is the basis of their appeal; scientists are struggling to figure out whether that can make them dangerous in the process, and how and why it happens.

Quantum dots are being pursued mostly in medicine and the electronics and energy sector. Their glow, for example, could help diagnose and target cancer. Companies are hoping they can use them in more efficient light bulbs and more brilliant television displays.

Click here for more Independent articles on nanotechnology.