Immunodiffusion is like a matching game for proteins. Imagine you have a bunch of different proteins, kind of like different puzzle pieces. Each protein has a specific shape that only matches with certain other proteins.
When scientists want to figure out what proteins are present in a sample, they can use immunodiffusion. They take the sample and add it to a special type of gel. This gel has little wells or holes in it.
Next, the scientists add a specific antibody to each well. Antibodies are like keys that fit into specific protein shapes. So each antibody is specific to just one protein.
The antibodies start to diffuse or move through the gel. If the sample had the matching protein, it will move towards the antibody in the well that matches with it. This is because the protein and antibody fit together like a lock and key.
If the sample doesn't have the matching protein, it won't move towards any of the wells.
When the antibodies and proteins match up, they make a little clump or line in the gel. The scientists can look at the gel under a microscope to see which proteins were in the sample.
So basically, immunodiffusion is like playing a matching game with proteins and antibodies.