CESELEX

CESELEX, or Capillary Electrophoresis-SELEX, is a molecular biology technique used to generate aptamers—short single-stranded nucleic acids that bind target molecules with high affinity. The method combines the classic SELEX process with capillary electrophoresis to separate bound from unbound sequences based on mobility.

A randomized library of DNA or RNA is incubated with the target. The mixture is subjected to capillary electrophoresis, where aptamer-target complexes and free oligonucleotides migrate differently. Fractions enriched for the complex are collected, amplified by PCR (DNA) or RT-PCR (RNA), and used in subsequent rounds. CE-SELEX typically requires far fewer rounds than conventional SELEX, often one to four cycles, yielding faster enrichment of high-affinity, specific aptamers.

The technique can be used with proteins, small molecules, and other targets, with detection commonly achieved by fluorescent labeling. Advantages include higher selection stringency and reduced library handling, while limitations may involve the need for suitable electrophoretic separation conditions and specialized instruments. The approach is widely used in aptamer discovery for diagnostics and therapeutics, with notable examples targeting thrombin and other biomolecules.

CESELEX was developed in the early 2000s as an adaptation of SELEX and remains a reference method in aptamer selection, often cited as CE-SELEX or CESELEX. It is one of several evolving strategies to accelerate the discovery of high-affinity nucleic acid ligands.