Recently, friends in Shanghai have received the new crown antigen test kit, and optimistic Shanghai citizens "self-deprecatingly" gave it a resounding name - "family poke".
Shanghai "new three-piece set" circle of friends brush screen!
Colleagues asked: Have you "stabbed the whole family"?
And, "I'm the squad leader I'm proud of" brush burst vibrato!
When Fei na Xiaobian received the kit, curiosity was on the head.
Is this thing really so magical? Can viruses really be detected?
Wait a minute... Written on the wrapping paper... Colloidal gold...
What does colloidal gold mean? Is there gold in it?
Curiosity is the most intolerable, immediately moved out of my almighty Finer electron microscope to take a look, "Antigen reagent, colloidal gold, what is a rare thing?" ”
Take apart the reagent, hey hey, smoothly find the "colloidal gold", this color is not "golden" is not?
Forget it, 1-2-3 on The Fina Electron Microscope!
After 1 minute... Oh, it looks like this
Colloidal gold pad: Magnification: 200X
Didn't you say it was gold? How is it fibrous? ... Don't die, keep zooming in, magnification to 5,000 times, wow! Is this densely packed with gold?
Colloidal Gold Pad: Magnification: 5,000X
Continue to zoom in, zoom in, to 50,000 times, and finally see your true face of Lushan, a dozen can be scored, and it is really gold.
Colloidal gold particles, magnification: 50,000X
Just this gold size is a bit small?
Don't be dead hearted, move out our particle statistical analysis measurement system, I want statistical statistics.
Statistical analysis of colloidal gold particles
This is dead hearted, the original colloidal gold "figure" is only 20-40 nanometers, pinch your fingers, a reagent belt of gold is not as much as your Alipay collar.
I am proud that I am a squad leader, and I want to tear down a "squad leader" to have a look
Again using the fina electron microscope for observation, the red C line here, under the lens, is deposited from nano gold.
At this point, the doubts in Xiaobian's heart were finally solved. Consult the literature to see how antigen kits work:
What about the fibrous colloidal gold pad that we see at a low magnification of the scanning electron microscope, which is fixed with gold label antibodies that can bind to the new crown virus (the gold particles we observed are part of the gold standard antibodies) to show the position of the antibodies on the test strip.
What magical process happens when an antibody is detected?
- Family Poke: Poke both nostrils for 15 seconds to get a sample
- Mix well: Mix the swabs well with the buffer and let stand for 1 minute
- Cover with lid and drop three drops: the buffer flows through the colloidal gold pad through capillary action, taking away the gold label antibody on the colloidal gold pad.
If the virus is present in the sample, it binds to the gold standard antibody to form a gold standard-virus complex. When continuing to flow through the T line, you will encounter a second group of antibodies that are "ambushed" at the T line, called T line antibodies, and the T line antibody will also bind to the virus to form a gold-virus-T line antibody complex, which precipitates and colorizes at the T line position, and the test result is positive.
If the virus is not present in the sample, the gold standard antibody will not bind to the secondary antibody of the T line, that is, it will not be deposited at the T line, and the T line will not be colored, indicating that the result is negative.
The C-line has a third group of antibodies, called C-line antibodies, which are not used to detect the new crown virus, but to capture the remaining free gold-label antibodies, and the horizontal line indicates that the result is valid.
You don't have to memorize the T-line C line so complicated, just remember: the antigen test result is negative on one bar, and if there are two bars "squadron leader", it is positive. The most important thing is: if there is a "squadron leader", don't take someone to interpret it! Whoever meets is a close contact! Honestly stay at home and immediately call the neighborhood committee to report it!
Please "babies" to spread this article:
If you are a parent, you can patiently tell your child the mystery of antigenic reagents, tell him how scientists make the virus appear through magical materials, and maybe plant a seed of "curiosity" for children who yearn for science.
Welcome to forward it to your biology teacher in middle school, through this example can let students better understand the difference between antibodies and antigens.
If you are a scientist, welcome to spread the text to your peers, Finer electron microscopy is indeed a good tool for nanomaterial characterization.
But most importantly, we hope that your spread will allow everyone who has seen this post to do a better job of testing when they receive antigen testing reagents, so that we can eliminate the virus earlier!
Fight the epidemic for the whole people! We need everyone's efforts!
Come on Shanghai! Come on China!
Finally, the antigen self-test process is attached
Citations
- "What should I do if there are two bars in antigen detection?" An article to interpret the difference between antigens and nucleic acid testing" - "A section of ginger"
- Revealed! What is the "gum gold test strip" used in antigen testing? Xinhua Daily