Sciencemadness Discussion Board

Extracting Gold Nanoparticles from SARS-CoV-2 Rapid Antigen Tests

Benj-NH2 - 21-5-2023 at 08:45

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?