Electrophoresis: The Technique for Separating Charged Particles Using Electric Fields
Electrophoresis is the technique that separates charged particles using an electric field. 1, 2
Principles of Electrophoresis
Electrophoresis works by applying an electric field to charged particles in a solution, causing them to migrate at different rates based on their:
- Charge-to-size ratio
- Molecular weight
- Shape
- Electric charge
The technique functions by applying a transient electric field that causes particles to move through a medium (such as a gel, buffer solution, or capillary tube) at different rates 1.
Types of Electrophoresis
Several variations of electrophoresis exist:
- Gel electrophoresis: Uses a gel matrix (polyacrylamide or agarose) to separate molecules
- Capillary electrophoresis (CE): Separates molecules in a thin buffer-filled capillary under high voltage 3
- Isoelectric focusing (IEF): Separates proteins based on their isoelectric points 1
- Isotachophoresis: A displacement electrophoresis technique offering increased resolution 2
Applications in Medicine and Science
Electrophoresis has numerous applications:
- Protein analysis: Separating proteins based on charge and size 4
- DNA/RNA analysis: Separating nucleic acid fragments
- Clinical diagnostics: Used in the diagnosis of various diseases 1, 3
- Pharmaceutical research: Drug development and quality control 1
- Genetic testing: Analysis of genetic material and identification of mutations 1
Advantages of Electrophoresis
- High sensitivity: Capillary electrophoresis can achieve separations with over 1 million theoretical plates per meter, 10× more sensitive than HPLC 3
- Speed: Some separations can be completed in less than 5 minutes 3
- Reproducibility: Often shows coefficient of variation (CV) less than 2% 3
- Versatility: Can be applied to various types of charged particles and molecules 1
Recent Advances
Recent developments have expanded electrophoresis capabilities:
- Nonlinear electrophoresis: Using liquid-crystalline nematic fluid allows for nonlinear effects, enabling transport of both charged and neutral particles 5
- Alternating current (AC) electrophoresis: Overcomes problems like electrolysis and absence of steady flows associated with direct current (DC) fields 6
- Electrophoretic-electroosmotic focusing (EEF): Separates membrane-bound proteins and charged lipids based on charge-to-size ratio 4
Importance in Modern Science
Since its development, electrophoresis has become fundamental to advances in:
- Biochemistry and molecular biology
- Genetics and gene technology
- Nucleic acid and protein sequencing
- Disease studies including cancer research
- Forensic medicine for identification of species and individuals 2
Electrophoresis remains one of the most powerful analytical techniques for separating charged particles and continues to evolve with new applications and methodologies.