What is Whole-cell SELEX? Whole-cell SELEX (Systematic Evolution of Ligands by EXponential enrichment) is a technique used to discover aptamers (single-stranded DNA or RNA molecules) that bind specifically to a target living cell. Unlike traditional SELEX that uses a purified protein target, whole-cell SELEX presents the target in its native, complex cellular environment. This allows for the selection of aptamers against: Native cell-surface proteins in their proper folding and post-translational modifications. Complex targets like transmembrane receptors in their natural lipid environment. Unknown surface biomarkers without prior knowledge of the cell's molecular makeup. Specific cell states (e.g., activated, cancerous, infected) based on differences in surface expression. The Core Process: How Whole-cell SELEX Works A professional service will manage this complex, iterative pipeline: Library & Design: Starting with a vast, random synthetic oligonucleotide library (10^14 - 10^15 unique sequences). Positive Selection: Incubating the library with the target cells (e.g., cancer cells, stem cells, bacteria). Aptamers that bind to any surface structure are retained. Counter-Selection (Critical Step): The bound pool is then exposed to non-target or control cells (e.g., healthy cells, a different cell line). Sequences that bind to these are discarded. This step is crucial for generating specificity. Elution & Amplification: Aptamers specifically bound to the target cells are recovered, amplified by PCR…
