What are quantum dots, and why are we making them out of tea?

Pedro_P

They're everywhere—and they can also treat cancer.
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Not a drop wasted.
DepositPhotos

▼ They’re tiny, they reflect and absorb light in useful ways, and they’re increasingly found in our homes: quantum dots. These fancy-sounding nanoparticles, which are called “quantum” because of their tiny size, have a number of commercial applications, from sensorsand solar cellsto TVsand cell phone chargers. They’re also used in medicine, where—among other things—they help doctors see cancerinside bodies and deliver drugs where they’re needed, hopefully without harming surrounding cells.
But though quantum dots sound like magic, the process of making them—and the materials they’re made from—do real harm to workers and the world around them. One prevalent way to make the dots is to synthesize them in a separate medium using a method called “colloidal synthesis.” Think muddy water: the dots are the dirt particles, and the stabilizing medium is the water, although the method here has many more steps than making mud. That medium is usually composed of hazardous biochemicals.
New researchfrom a team of scientists in the UK and India demonstrates that it’s possible to make quantum dots using waste from the tea industry. About one third of each tea crop produced around the world isn’t used to make drinkable tea, says Sudhagar  Pitchaimuthu, the study’s corresponding author. Pitchaimuthu, who is a research fellow at Swansea University, spends most of his time looking for novel compounds that are currently going to waste, like these tea leaves, and seeing how they can be used to make new products rather than just heading to a landfill. (▪ ▪ ▪)

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