Extracting Gold Nanoparticles from SARS-CoV-2 Rapid Antigen Tests
Some Covid tests contain gold nanoparticles that have special antibodies on their surface, which can bind with viral antigens and are responsible for
the positive test outcome.
(For further information on how these tests work, you can refer to:
https://www.youtube.com/watch?v=2B-iZGNiPA0&t=236s
https://www.youtube.com/watch?v=s_usIkrVQwE)
Since I still have some tests lying around at home, I wanted to try extracting the gold from them... Of course, this procedure is not profitable and
doesn't yield any significant amount of gold. It's just for fun.
I took the tests and placed them in a dilute solution of sodium cyanide. Normally, this reaction takes quite a while but firstly, there isn't a lot of
gold to react with... and you can speed up the reaction by adding some hydrogen peroxide. However, you must be careful to keep the pH alkaline to
avoid producing toxic HCN gas. Just add a sufficient amount of NaOH to keep it nice and basic.
The reaction follows the Elsner equation:
4 Au + 8 NaCN + O2 + 2 H2O → 4 Na[Au(CN)2] + 4 NaOH
The produced solution is now reacted with ascorbic acid in order to reduce the metal salt to nanoparticles (you could also heat the solution a bit)
The initially colourless solution turned reddish/ brownish afterwards and judging by the color of commercial gold nanoparticles I hope, that I managed
to produce some miniscule amount of them.
Maybe in the future I will get around to doing some further testing on the product (UV-visible absorbance spectroscopy?) but I must get round to
building this device xD…
(https://link.springer.com/article/10.1186/s11671-020-03370-5)
Any thoughts, improvements,… on this topic?
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