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…
Core Components of a Small Molecule Target Service A comprehensive service follows the early drug discovery workflow: 1. Target Identification & Prioritization Bioinformatics & Omics Analysis: Mining genomic, proteomic, and clinical data to find proteins or pathways dysregulated in a disease. Genetic Screens: Using CRISPR-Cas9 or RNAi to knock out/knock down genes and identify which are essential for disease cell survival. Literature & Database Mining: Systematic review of existing scientific and patent data to propose novel or repurposable targets. 2. Target Validation In Vitro Models: Confirming the target's role in disease using engineered cell lines (overexpression, knockout) and relevant disease models (e.g., cancer cell lines, neuronal cultures). In Vivo Models: Using animal models (e.g., zebrafish, mice) to see if modulating the target (genetically or with a tool compound) has the desired therapeutic effect and is safe. Biochemical Validation: Demonstrating the target protein is expressed, has the expected activity, and is "druggable" (has a pocket where a small molecule can bind). 3. Assay Development & Screening This is a critical service. Providers develop robust tests ("assays") to measure target activity. Types of Assays: Biochemical Assays: Test compound binding/interaction with the purified target protein (e.g., enzymatic activity, protein-protein interaction). Cell-Based Assays: Test compound function in a living cell (e.g., reporter…
