What is the Service? It's the process of using SELEX (Systematic Evolution of Ligands by EXponential Enrichment) to identify single-stranded DNA or RNA aptamers that can bind to a target cytokine. The service takes you from target selection to delivering validated aptamer candidates. Standard Workflow (What the Provider Does) Project Scoping & Target Preparation: Target: You specify the cytokine (e.g., TNF-α, IL-6, IFN-γ). The provider may require you to supply the purified, recombinant protein or offer to procure/produce it. Counter-SELEX: A critical step to ensure specificity. The provider will use related proteins (e.g., other cytokines, serum proteins) to eliminate aptamers that bind non-specifically. Library Design & SELEX Cycle: Starts with a vast random oligonucleotide library (10^14 - 10^15 unique sequences). Iterative rounds (8-15+) of: Binding: Incubating the library with the target cytokine. Partitioning: Separating bound from unbound sequences (e.g., via immobilization on beads, filters, or capillary electrophoresis). Amplification: PCR (for DNA) or RT-PCR (for RNA) to enrich the binding sequences. Stringency Increase: Gradually increasing washing rigor and introducing counter-selection to drive selection of high-affinity, specific binders. Next-Generation Sequencing (NGS) & Bioinformatics: After the final rounds, the enriched pool is sequenced using NGS. Bioinformatics tools analyze the data to identify enriched sequence families, consensus motifs, and predict secondary structures.…
What is an Aptamer? An aptamer is a short, single-stranded oligonucleotide (DNA or RNA) that folds into a unique 3D structure, allowing it to bind to a specific target molecule (like a protein) with similar specificity to an antibody. They are often called "chemical antibodies." Why Use a Screening Service Instead of In-House Development? Expertise & Equipment: The screening process (SELEX) requires specialized skills, robotics, and next-generation sequencing (NGS) infrastructure. Time & Cost Efficiency: Outsourcing can be faster and more cost-effective than setting up a new, complex pipeline. Higher Success Rate: Experienced providers have optimized protocols for difficult targets (e.g., membrane proteins, toxic proteins). The Core Process: SELEX The standard method is SELEX (Systematic Evolution of Ligands by EXponential Enrichment). A professional service will offer advanced variants of this process. A Typical Service Workflow: Project Consultation & Design: Target Characterization: Discussion about your protein (purified? membrane-bound? post-translational modifications?). Selection Strategy: Choosing the best SELEX method (e.g., Capillary Electrophoresis-SELEX (CE-SELEX) for very high affinity, Cell-SELEX for cell-surface targets, Toggle-SELEX for cross-species specificity). Counter-Selection: Designing the process to avoid binding to non-target proteins (e.g., carrier proteins, related isoforms). Library Synthesis & Preparation: Creation of a vast random oligonucleotide library (typically 10¹³ - 10¹⁵ unique sequences). The Selection Rounds (Cycles of SELEX): Binding: Incubating the library with the…
