Vittorio Saggiomo (@Vsaggiomo@bsky.social) Profile picture
Associate prof BioNanoTechnology @WUR (ex @kieluni, @univgroningen, @UninaIT). Tech+Chem = microfab, 3D printing, Sensors & Devices. Nerd, gamer, and bad artist

Apr 17, 2021, 18 tweets

I should be writing, but ......
As those are now available in supermarkets, shall we take a look?

So, it’s a swab, apparently not a deep swab though. Polyoxymethylene and a sponge, sterile and approved for medical use

Then we have the buffer, not sure what’s in here. It’s an antigen test so there shouldn’t be any lysis required, but maybe a deactivation step?

Then we have a drip unit with a filter, which is quite nice actually. So you can count the single droplets and filter off some buggers :D

The lateral flow assay comes with silica gel, and the “Ag” sounds too obvious for silver nano particles

Time wise 15-30 min, so it is as “rapid” as any LAMP genetic detection -_-

@L_Howes was right, it’s not silver, it’s a classic gold nanoparticle conjugate....

No surprises in here, very standard lateral flow (at the end I’ll link some videos for explaining how they work)

Sensitivity and specificity seems good, but they have a lot of interferences from other viruses (thing you’ll not have with genetic amplification tests)

Ok, less talky talky and more swabby swabby :D

Ok, this is impossible.... I don’t use contact lenses because I don’t like to poke my eyes, reaching this depth in the nose is a huge failing point of the test

While we wait for the test, let’s check the waste produced:
Silica gel (avoidable)
Swab (multimaterial)
Buffer and dripper (multimaterial)
Lateral flow (abs?)
All of them non recyclable / non biodegradable

imho

Pro: the dripper is very nice for delivering and filtering droplets (known amount of liquid)

Cons: same time of LAMP, interference from other viruses, stabbing yourself in the nose (false negative?), waste produced for a single test

Not sure what’s in the liquid, buffer?

What’s also missing in any antigen test is the amplification step, so it can only detect “high”amount of virus. And this is why you need to go as deep as possible with the swab. You need to collect as many viruses as possible.

Btw, I’m negative :)

So I guess that my main concerns here are the swab part (may give plenty of false negatives is not performed correctly) and the waste produced.

If you want to know more on how lateral flow assay work, I did an explanation here:

and here I dissect a lateral flow pregnancy test:

but I guess that next year I'll use this SARS-CoV2 lateral flow test for my course :)

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