Core Principle & Typical Service Workflow A professional service for Conventional SELEX typically follows this established, iterative cycle (8-15 rounds), as visualized below: Key Service Characteristics Target Immobilization: The target molecule is fixed to a solid support (e.g., magnetic beads, column resin, nitrocellulose membrane). Positive Selection: The library is passed over the immobilized target. Sequences with some binding affinity are retained, while others are washed away. Stringency Control: The service provider systematically increases selection pressure across rounds (e.g., by reducing target concentration, increasing wash stringency, adding counter-targets in Negative SELEX steps) to drive the evolution of high-affinity, specific binders. Monitoring: Enrichment is tracked via quantitative PCR, and final pools are analyzed by Next-Generation Sequencing (NGS) to identify convergent sequence families. Common Applications for this Service This classic approach is ideal for: Proteins that are stable and can be immobilized without losing native conformation (e.g., antibodies, enzymes, recombinant tags). Large molecules or complexes (e.g., viruses, whole cells—though Cell-SELEX is now more common for cells). Establishing proof-of-concept for a new target class where simpler, robust methodology is preferred. Deliverables Similar to other SELEX services, clients receive: A final report detailing the selection process and conditions. A list of top-ranked aptamer sequences with affinity (Kd) and specificity data. Aliquots of synthesized, validated…
