Evolution of capillary electrophoresis: disease diagnosis and monitoring

The first electrophoresis experiments were carried out by Tiselius as detailed in his thesis entitled The moving banding method to study the electrophoresis of proteins, published in 1930. He was awarded the 1948 Nobel Prize in Chemistry for his research on electrophoresis and discoveries concerning the complex nature of serum proteins. Tiselius utilised the electric charge carried by proteins to achieve separation, and was the first to isolate albumin successfully from the α-, β- and γ-globulins.¹  

Electrophoresis techniques have evolved from using paper as the separation medium through to using cellulose acetate, agarose gel and then capillary electrophoresis. Using a small capillary filled with buffer, capillary electrophoresis separates ionic species based on the ratio of their size to their charge. This technique can be used to separate simple molecules, organic and inorganic ions, peptides, proteins, carbohydrates and nucleic acids.¹ It is the only electrophoretic technique that does not require a supporting substrate, as the analysis is carried out in free aqueous solution.

The benefits of capillary electrophoresis were first recognised by Jorgenson and Lukacs in 1981 and, following further developments in the 1990s, the technique has been used for over 18 years for the routine analysis of serum proteins to diagnose and monitor disease.²

Capillary electrophoresis
Electrophoresis is defined as the migration of ions by attraction or repulsion in an electric field. In practice, a positive anode and negative cathode are placed in a buffer solution containing the compound of interest, a voltage is applied across the electrodes and the analyte ions migrate towards the electrode of opposite charge. In traditional gel electrophoresis, analytes move in a conductive liquid medium, whereas capillary electrophoresis separates species in a buffer-filled capillary with an internal diameter of 25–100 µm.³ Typical voltages for protein separation using capillary electrophoresis range from 7000 to 10,000 V, depending on the analyte to be separated.