There are many ways to learn a new game. You might read the instructions. You might look at diagrams of the game board. You might watch other people playing. You might even play the game yourself.
Similarly, when trying to understand how a cell works, researchers do all of these things. They read the cell’s DNA to learn what it encodes, they use special microscopes to get high definition pictures of cellular components, they watch the cell grow, and sometimes they even try to build new cells.
For all of these techniques to work, we must be able to observe key components of the games or cells under study. For example, if you were trying to learn how to play soccer and couldn’t see what was going on, you’d have a hard time learning the game. To study how a protein works, a researcher must be able to observe the protein in cells. The same is true for chemicals, DNA, and many other molecules a researcher might like to study inside a cell – you must be able to observe, measure and identify these things in order to learn what they do.
What is a biosensor?
A biosensor is one type of tool a researcher can use to observe molecules in cells. Biosensors are devices made of biological components like DNA or proteins (hence bio) and they detect or “sense” when different types of molecules are nearby (hence sensor). Biosensors report that they have detected something through an easily observable signal. You can think of biosensors like friends explaining a game to you for the first time, and showing you clearly what is going on. If the game was soccer, they could point to the goalie and say “That’s the goalie” and also scream “GOOOAAALLLLLL!!!” when a goal has been scored.
Biosensors work in many different ways but they often give researchers visual cues to show that they have detected specific molecules. For instance, some biosensors will start to glow red if there is a particular chemical in a cell. Other glowing biosensors will attach to specific sequences of DNA to show where those pieces of DNA are. Still other biosensors will make cells turn blue only if two proteins interact with each other.
What are biosensors used for?
One interesting biosensor that I learned about recently is called iGluSnFr. This cleverly named biosensor glows bright green when it detects a chemical called glutamate. This ability is useful because glutamate is transferred between some cells of the brain when they communicate. You can therefore use iGluSnFr to determine if cells in the brain are talking to each other and even measure brain responses to things like visual cues. In this particular case, detecting glutamate serves as a proxy to tell researchers “Hey! These cells are talking to each other!”
Of course this is just the tip of the iceberg for biosensors. Researchers have produced biosensors to measure levels of toxic waste, to measure the acidity of cells, and even to detect Zika virus. Everyday, scientists are using biosensors to learn the rules of life and, as they get more precise, you may see these cool tools used to diagnose and treat disease!