Tissue-SELEX Aptamer Screening Service This refers to a specialized contract research service that uses Systematic Evolution of Ligands by EXponential Enrichment (SELEX) to discover aptamers that specifically bind to molecular targets within a complex tissue environment, rather than purified proteins or isolated cells. Core Concept & Key Differentiator While Cell-SELEX uses whole live cells as targets, Tissue-SELEX advances the complexity by using: Tissue sections (fresh, frozen, or FFPE - Formalin-Fixed Paraffin-Embedded) Tissue homogenates Tissue-specific extracellular matrix (ECM) components The goal is to find aptamers that recognize targets in their native, histological context, preserving post-translational modifications and local microenvironments. This is crucial for developing reagents for histopathology and tissue-specific targeting. Typical Workflow Target Preparation: Provider prepares or client supplies well-characterized tissue sections (often on glass slides). Counter-selection tissues (e.g., healthy vs. diseased, organ A vs. organ B) are critical. SELEX on Tissue: The oligonucleotide library is incubated directly on the tissue section. After washing, bound sequences are eluted, often by laser capture microdissection of bound areas or direct extraction. Amplification & Iteration: Recovered sequences are amplified (PCR) and used for subsequent selection rounds, with increasing stringency. Sequencing & Analysis: High-throughput sequencing (NGS) identifies enriched sequence families. Validation: Top candidates are synthesized and validated via: Tissue Staining: Fluorescently-labeled aptamers used like antibodies in immunohistochemistry (IHC). Specificity: Testing on…
What is a Stem Cell Aptamer Screening Service? It is a contract research service where a specialized lab uses Systematic Evolution of Ligands by EXponential Enrichment (SELEX) to discover and develop DNA or RNA aptamers that bind with high affinity and specificity to a target of your choice related to stem cells. Aptamers are often called "chemical antibodies." They are short, single-stranded oligonucleotides that fold into unique 3D shapes, allowing them to bind to targets like proteins, small molecules, or even whole cells. Core Targets for Stem Cell Applications The service can be tailored to screen for aptamers against: Specific Cell Surface Markers: (e.g., CD34, CD133, SSEA-4, TRA-1-60) for identification and isolation. Whole Live Stem Cells: To get aptamers that recognize the unique molecular signature of a specific stem cell type (e.g., mesenchymal stem cells, cancer stem cells, pluripotent stem cells). Differentiation State-Specific Targets: To distinguish between pluripotent, progenitor, and fully differentiated cells. Specific Stem Cell-Derived Products: (e.g., exosomes, vesicles). Typical Workflow of the Service A professional service provider will guide you through these stages: Phase Description Your Input 1. Project Design Defining the target (specific protein, cell line, primary cells), counter-selection cells (to ensure specificity), and desired aptamer properties (e.g., Kd, nuclease resistance). Provide target cells, control cells, and…
What is a Bacterial Aptamer Screening Service? It is a specialized contract research service where a provider uses Systematic Evolution of Ligands by Exponential Enrichment (SELEX) to discover and develop single-stranded DNA or RNA aptamers that bind with high affinity and specificity to a bacterial target. The target can be: Whole bacterial cells (e.g., E. coli O157:H7, Salmonella typhimurium). Specific bacterial components (e.g., surface proteins like pili, flagella, capsular polysaccharides, secreted toxins). Key virulence factors (e.g., endotoxins like LPS). The resulting aptamers are powerful recognition elements for diagnostics, therapeutics, and research. Core Steps in the Service Pipeline A typical full-service offering includes: 1. Project Design & Target Preparation: Consultation: Defining the goal (e.g., detection of a specific strain, therapeutic neutralization). Target Choice: Deciding between whole cells (for broad detection) or purified components (for precise targeting). Counter-SELEX: Using related non-target cells (e.g., non-pathogenic strain) to eliminate cross-reactive aptamers and ensure specificity. 2. Library Synthesis & SELEX Process: Library Design: Using a random-sequence oligonucleotide library (typically ~10^14 different molecules). Selection Rounds (8-15 cycles): Iteratively incubating the library with the target, washing away unbound sequences, eluting the bound ones, and amplifying them via PCR (for DNA) or RT-PCR (for RNA). Monitoring: Using quantitative PCR or flow cytometry to track enrichment progress. 3. Next-Generation Sequencing (NGS) & Bioinformatics:…
