Okay kiddo, so imagine there is a special protein called annexin A5 that likes to stick to certain things in our body. We want to find out how much it likes to stick to something called phosphatidylserine (don't worry about that big word for now). So, scientists made a test to measure how strong the attachment between annexin A5 and phosphatidylserine is.
They do this by taking a tiny plate and putting a small amount of phosphatidylserine on it. Then, they add different amounts of annexin A5 to each sample. The amount of annexin A5 that sticks to the phosphatidylserine tells us how much it likes to stick to it.
Now, just like when you color and stay in the lines, scientists want to make sure they only measure how much annexin A5 sticks to the phosphatidylserine and nothing else. So, they add a dye that changes color based on how much annexin A5 is stuck to the plate. They can then measure how much dye there is to figure out how much annexin A5 is attached to the phosphatidylserine.
This is called an annexin A5 affinity assay and helps scientists understand how strong the bond is between annexin A5 and phosphatidylserine. It’s like making a recipe and wanting to make sure we use the right ingredients in the right amounts.