Students may have noticed the many hand sanitisers around the school but they may not have stopped to think about how they actually kill the germs on our hands.
To understand this, we first need to think about the structure of the bacteria cells that we are trying to kill. The bacteria cell is a microscopic, prokaryotic cell. It is smaller than the cells of our body and has an outer membrane made of fatty acids. One role of this membrane is to hold the cells important inner structures together. Within the cell, are proteins made up of amino acids in a specific shape that allows them to carry out their function.
The alcohol (often ethanol) does two important things. Firstly, it breaks down the protective layer of the cell membrane, exposing the proteins within. The alcohol then penetrates the bacteria and denatures the proteins, meaning it changes their shape so that they can no longer carry out their function. With their membrane broken down and their proteins denatured, the potentially harmful bacteria rapidly die.
The added benefit of ethanol being very volatile, results in rapid evaporation from your hands, making it an excellent chemical to use as hand sanitiser. So next time you are cleaning your hands around school, remember the amazing biochemistry that is helping to stop the spread of germs and keep you healthy.