Sudsy Cells
Students culture cells in order to find out which type of surfactant (in this case, soap) is best at removing bacteria. Groups culture cells from unwashed hands and add regular bar soap, regular liquid soap, anti-bacterial soap, dishwasher soap, and hand sanitizer to the cultures. The cultures are allowed to grow for two days and then the students assess which type of soap design did the best job of removing bacteria cells from unwashed hands. Students extend their knowledge of engineering and surfactants for different environmental applications.
Which type of soap is most effective at killing bacteria?Copyright Flickr https://www.flickr.com/photos/oatsy40/7381870492
Engineers spend a lot of time trying to prevent the spread of bacteria cells that make humans sick. One example of products designed by engineers is surfactants or soaps that remove bacteria cells from our hands. Surfactants are compounds that act as wetting agents to decrease the interface tension of two liquid, such as oil and water. Engineers design surfactants for a variety of applications including detergents, emulsifiers, paints, adhesives, agrochemicals, biocides, and soil and water remediation.
After this activity, students should be able to:
- Describe how surfactants work to remove surface tension between two compounds.
- Understand how engineers use processes to evaluate the effectiveness of different designs.
- Describe the effect of adding surfactant to a prokaryotic cell.
- List several engineering applications of surfactants in everyday life.