When you think of electric fields, you likely think of electricity – the stuff that makes modern life possible by powering everything from household appliances to cellphones. Researchers have been studying the principles of electricity since the 1600s. Benjamin Franklin, famous for his kite experiment, demonstrated that lightning was indeed electrical.
Electricity has also enabled major advances in biology. A technique called electrophoresis allows scientists to analyze the molecules of life – DNA and proteins – by separating them by their electrical charge. Electrophoresis is not only commonly taught in high school biology, but it’s also a workhorse of many clinical and research laboratories, including mine.
I am a biomedical engineering professor who works with miniaturized electrophoretic systems. Together, my students and I develop portable versions of these devices that rapidly detect pathogens and help researchers fight against them.
Electrophoresis is a staple in high school classrooms and research labs alike.
What is electrophoresis?
Researchers discovered electrophoresis in the 19th century by applying an electric voltage to clay particles and observing how they migrated through a layer of sand. After further advances during the 20th century, electrophoresis became standard in laboratories.
To understand how electrophoresis works, we first need to explain electric fields. These are invisible forces that electrically charged particles, such as protons and electrons, exert on each other. A particle with a positive electrical charge, for example, would be attracted toward a particle with a negative charge. The law of “opposites attract” applies here. Molecules can also have a charge; whether it’s more positive or negative depends on the types of atoms that make it up.
In electrophoresis, an electric field is generated between two electrodes connected to a power supply. One electrode has a positive charge and the other has a negative charge. They are positioned on opposite sides of a container filled with water and a little bit of salt, which can conduct electricity.
When charged molecules such as DNA and proteins are present in the water, the electrodes create a force field between them that pushes the charged particles toward the oppositely charged electrode. This process is called electrophoretic migration.
Pathogens have distinct electrical charges and can be separated by measuring how quickly they move through electrophoresis.
Blanca H. Lapizco-Encinas, CC BY-SA
Researchers like electrophoresis because it is fast and flexible. Electrophoresis can help analyze distinct types of particles, from molecules to microbes. Further, electrophoresis can be carried out with materials such as paper, gels and thin tubes.
In 1972, physicist Stanislav Dukhin and his colleagues observed another type of…
