Elektroforeesi

Elektroforeesi, or electrophoresis, is a laboratory technique that separates charged molecules by applying an electric field to a conductive medium. Molecules migrate toward the electrode of opposite charge, and their rate of movement depends on size, charge density, and shape. A gel or capillary acts as a matrix that provides resistance, enabling separation based on these properties.

Common forms include gel electrophoresis, where samples are loaded into wells in agarose (for nucleic acids) or polyacrylamide (for proteins). Denaturing conditions use detergents such as SDS to give proteins a uniform charge-to-mass ratio, while native conditions preserve structure. Isoeletric focusing and two-dimensional gel electrophoresis offer higher resolution by separating molecules first by charge at a fixed pH and then by size.

Capillary electrophoresis uses narrow capillaries and high electric fields, producing fast, high-resolution separations with small sample volumes; it is widely used for nucleic acids, small metabolites, and certain proteins.

Visualization is achieved with dyes (for nucleic acids) or staining methods (for proteins); detection can be via UV or blue-light transilluminators and imaging systems.

Applications span basic science, diagnostics, forensic science, and quality control. Electrophoresis is used to estimate molecular sizes, assess purity, monitor PCR products, analyze nucleic acid sequences, and study protein expression.

Historical note: the method traces to Arne Tiselius in the 1930s, with later developments in gel-based and capillary formats expanding its range and resolution.