What is an Aptamer? First, a quick reminder: Aptamers are short, single-stranded DNA or RNA oligonucleotides that bind to a specific target with high affinity and specificity. They are often called "chemical antibodies." The Core Service: SELEX (The Screening Process) The service revolves around executing a SELEX (Systematic Evolution of Ligands by EXponential enrichment) campaign. This is an iterative, in-vitro combinatorial chemistry process that screens a vast random library (10^14 - 10^15 unique sequences) to find the few that bind your target. A standard SELEX workflow includes: Library Design & Synthesis: Creating the initial random oligonucleotide pool. Incubation: The library is exposed to the target. Partitioning: Bound sequences are separated from unbound ones (the most critical step, varying by target type). Amplification: The bound sequences are amplified (usually by PCR for DNA, RT-PCR for RNA). Counter-Selection (Negative Selection): To increase specificity, the pool is exposed to non-target surfaces (e.g., immobilization matrix, related proteins) to remove non-specific binders. Repetition: Steps 2-5 are repeated for 8-15 rounds until a high-affinity pool is enriched. Cloning & Sequencing: The final pool is cloned, and individual aptamer sequences are identified via Next-Generation Sequencing (NGS). Bioinformatics & Analysis: NGS data is analyzed to identify candidate sequences, often clustered into families based on sequence/structure motifs. Characterization: Top candidates…
