Capillary Electrophoresis SELEX (CE-SELEX) Aptamer Screening Service is a highly efficient, solution-phase selection technology that uses capillary electrophoresis to separate target-bound aptamer sequences from unbound ones based on their charge-to-size ratio shift, rather than on physical immobilization. It is renowned for its ability to generate high-affinity aptamers with fewer selection rounds and with exceptional stringency. Core Principle: Separation by Mobility Shift In a capillary filled with buffer, an electric field is applied. All molecules migrate based on their net charge and size (their electrophoretic mobility). The target molecule (e.g., a protein) has a specific mobility. A single-stranded DNA or RNA library has a different, faster mobility (due to its high negative charge/size ratio). When an aptamer binds to the target, it forms a complex. This complex has a distinctly different mobility (usually slower) than the free library. CE instrumentation with on-column UV or fluorescence detection can precisely collect only the shifted peak containing the target-aptamer complexes, physically discarding >99.9% of unbound sequences in a single round. Typical CE-SELEX Service Workflow 1. Project Design & Characterization: Consultation: Defining the purified, soluble target (ideal for proteins, peptides, small molecules). Mobility Calibration: The service provider first runs the target and the naïve library separately to establish their baseline migration times. 2. The Selection…
