Electrophoresis: Separating Molecules with Precision

Date of publication: 24. March, 2023

What is electrophoresis?

Electrophoresis is a powerful laboratory technique that separates and analyzes molecules based on their size, charge, and other physical properties. It has become an indispensable tool for many fields of scientific research, including biochemistry, molecular biology, genetics, and proteomics.


The principle of electrophoresis is simple: an electric field is applied to a sample containing molecules with different properties, causing them to move through a medium such as a gel or a solution. The movement of the molecules is influenced by their size and charge, as well as the medium’s properties and the electric field’s strength.


Different types of electrophoresis are used to separate different types of molecules, such as proteins, nucleic acids, and carbohydrates. This article will explore the principles and applications of electrophoresis and some of the fundamental techniques and technologies used in this field.

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Principles of Electrophoresis

Electrophoresis is based on the fact that charged molecules will move in an electric field. This movement is influenced by several factors, including the size and shape of the molecule, the charge on the molecule, the strength of the electric field, and the properties of the medium through which the molecule is moving.


The medium used in electrophoresis can be a gel or a solution. In gel electrophoresis, the sample is loaded onto a gel matrix, usually agarose or polyacrylamide. The gel matrix acts as a molecular sieve, separating the molecules based on size. Smaller molecules can move through the gel more easily than larger molecules, so that they will travel farther in a given amount of time.


The sample is dissolved in a buffer solution containing a charge-carrying electrolyte in solution electrophoresis. The electrolyte allows the current to flow through the sample and also helps minimize pH changes in the sample during electrophoresis. The sample is placed in a chamber with two electrodes, one at each end, and an electric field is applied across the chamber. The molecules in the sample will move toward the electrode with the opposite charge.

article DNA samples

Applications of Electrophoresis

Electrophoresis has many applications in scientific research, particularly in biochemistry, molecular biology, genetics, and proteomics. Two-dimensional gel electrophoresis (2DGE) is a popular technique that can separate thousands of proteins in a single sample. The proteins are first separated based on their isoelectric point (pI) in the first dimension and then based on their molecular weight in the second dimension. This allows researchers to analyze a cell or tissue’s entire proteome and identify changes in protein expression under different conditions.

Nucleic acid analysis: Electrophoresis is also used to analyze nucleic acids, particularly DNA and RNA. Agarose gel electrophoresis is a common technique for separating DNA fragments based on size. The DNA is loaded onto a gel matrix, and an electric field is applied. The DNA fragments will migrate through the gel, with smaller fragments traveling farther than larger fragments. This allows researchers to separate DNA fragments for analysis, such as sequencing or restriction enzyme digestion.


Clinical diagnostics: Electrophoresis identifies and quantifies proteins or enzymes in blood or urine samples. This can be useful for detecting diseases such as diabetes, liver disease, or cancer and monitoring the effectiveness of treatments.

DNA structure article

Techniques and Technologies in Electrophoresis

Z leti so bile razvite številne tehnike in tehnologije za izboljšanje natančnosti, občutljivosti in hitrosti elektroforeze. Nekatere temeljne tehnike in tehnologije, ki se uporabljajo pri elektroforezi, vključujejo kapilarno elektroforezo (CE).


Kapilarna elektroforeza je tehnika visoke ločljivosti, s katero lahko ločimo in analiziramo majhne molekule, kot so aminokisline, peptidi in nukleotidi. Uporablja ozko kapilarno cevko, napolnjeno z ločilnim medijem, vzorec pa se vbrizga na enem koncu kapilare. Čez kapilaro deluje električno polje, molekule v vzorcu pa migrirajo skozi kapilaro glede na svoj naboj in velikost. CE je koristna za analizo kompleksnih mešanic, kot so metaboliti ali zdravila.

Eden od naših ključnih izdelkov je oprema za elektroforezo, ki vključuje sistem Qiaxcel connect – napravo za kapilarno elektroforezo podjetja Qiagen.

Qiagen article Qiaxcel connect

Gel-free electrophoresis: Gel-free electrophoresis techniques have been developed to overcome some of the limitations of traditional gel electrophoresis, such as poor sensitivity, resolution, and reproducibility. These techniques use alternative separation media, such as ion exchange chromatography or isoelectric focusing, to separate and analyze proteins or peptides.


Multiplexed electrophoresis: Multiplexed electrophoresis techniques allow multiple samples to be analyzed simultaneously on a single gel or capillary. This can save time, reduce sample handling, and allow for direct comparisons between samples. Multiplexed electrophoresis can be achieved by using different fluorescent labels on each sample or different sample loading wells on a single gel or capillary.

Next-generation sequencing (NGS): Next-generation sequencing is a powerful technique that can parallel sequence millions of DNA fragments. NGS has revolutionized the field of genomics, allowing researchers to sequence entire genomes, transcriptomes, or epigenomes in a single experiment. NGS relies on electrophoresis to separate and amplify DNA fragments sequenced using high-throughput technologies.eneracije je zmogljiva tehnika, ki lahko vzporedno sekvencira milijone fragmentov DNA. NGS je revolucionirala področje genomike, saj raziskovalcem omogoča sekvenciranje celotnih genomov, transkriptomov ali epigenomov v enem samem poskusu. NGS temelji na elektroforezi za ločevanje in pomnoževanje fragmentov DNA, ki se sekvencirajo z visoko zmogljivimi tehnologijami.

So what is electrophoresis?

Electrophoresis is a versatile and powerful technique that has revolutionized many fields of scientific research. It allows for separating and analyzing molecules based on their size, charge, and other physical properties. It has many applications in biochemistry, molecular biology, genetics, and proteomics. Over the years, many different techniques and technologies have been developed to improve electrophoresis’ precision, sensitivity, and speed, including capillary electrophoresis, gel-free electrophoresis, multiplexed electrophoresis, and next-generation sequencing. As scientific research advances, electrophoresis will remain a crucial tool for separating and analyzing molecules.