School of Life Sciences | Ask A Biologist

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Why is Rudolp's nose red?

Nanoparticles Stick

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  • Antibody: a molecule made by B-cells to trap foreign particles and microbes... more
  • Bind: attaching two things together.
  • Nanoparticle: a very tiny object, often thought of as a small piece of matter measured on the nano-scale (between 1 and 100 billionths of a meter long).
  • Protein: a type of molecule found in the cells of living things, made up of special building blocks called amino acids.

Nanoparticles Stick

As nanoparticles search far and wide for the cells they want to target, they need to keep their trusty antibodies by their side. Otherwise they’d never be able to tell which cells to go to. But how do the antibodies know where to go when the nanoparticles don’t?

Well it isn’t magic. Antibodies are shaped just right so that they can fit a specific protein exactly, like two pieces of a puzzle, or a lock and key. Once scientists know which proteins are found only on the surface of the cell they want to target, it’s just a matter of making antibodies that fit them.

Antibody Parts and How they Work

Labeled antibodyAntibodies are made of four separate proteins: two heavy chain proteins and two light chain proteins. They are called chains because they are long, skinny, flexible proteins. The two light chains are stuck onto the heavy chains using a strong bond type called a disulfide bond.

The parts of the antibody that are blue in the picture are the same for every single antibody. This is important, because this is the part that sticks to the nanoparticle. If the nanoparticles bind to this part that never changes, then they don’t have to be limited to the kinds of antibodies they can have.

Antibodies also have parts at the ends, shown in purple, that are different for each antibody. These are the parts that can recognize and bind to a specific protein. Immune cells can produce around a million different protein binding sites on the antibodies they make. Each cell makes a different antibody, and when finds a foreign protein that its antibodies bind to, it will start making tons more. 

Complex Key

Antibodies are a lot like keys that only fit in certain locks. The proteins at the end of the antibody helps determine where it can fit.

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Complex Key

Antibodies are a lot like keys that only fit in certain locks. The proteins at the end of the antibody helps determine where it can fit.

Nano Medicine icon Play Game

Share to Google Classroom

Be part of Ask A Biologist

by volunteering, or simply sending us feedback on the site. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteer page to get the process started.