electroforesis

Electroforesis is a laboratory technique used to separate charged biomolecules, such as nucleic acids and proteins, by their movement in an electric field through a supporting medium. When a potential is applied, molecules migrate toward the opposite electrode; their speed depends on their charge-to-size ratio, shape, and the properties of the medium, including pH and ionic strength.

The most common form is gel electrophoresis. In agarose gels, DNA and RNA fragments are separated mainly by size, with smaller fragments moving faster. Polyacrylamide gels provide higher resolution for proteins or small nucleic acids and can be used in denaturing forms (for example, SDS-PAGE for proteins, which imparts a uniform charge-to-m mass ratio) or in native forms that preserve structure and interactions.

Capillary electrophoresis uses narrow capillary tubes filled with buffer, offering high resolution and fast separations with small sample volumes. It includes variants such as capillary zone electrophoresis and capillary gel electrophoresis, and detection is typically by UV or fluorescence.

Two-dimensional electrophoresis combines two sequential separations, usually first by isoelectric point and then by size, to achieve very high resolution of complex protein mixtures, and is widely used in proteomics.

Applications span molecular biology and medicine: analysis of DNA fingerprints and PCR products, RNA assessment, genotyping, sequencing preparation, protein purity testing, and clinical diagnostics. Visualization often relies on stains or dyes for nucleic acids (e.g., ethidium bromide, SYBR Safe) or proteins (e.g., Coomassie blue, silver stain), sometimes with radiolabels or fluorescence. Safety and equipment considerations include handling hazardous reagents, disposing of waste, and ensuring appropriate markers and standards for interpretation.