6-Carboxytetramethylrhodamine succinimidyl ester | CAS 150810-69-8

6-Carboxytetramethylrhodamine succinimidyl ester is a reactive rhodamine-based fluorescent dye supplied as an N-hydroxysuccinimide (NHS) ester, designed for efficient covalent labeling of primary amine groups. Its bright, red-orange fluorescence makes it widely used for preparing fluorescent conjugates for microscopy, imaging, and quantitative fluorescence workflows. The dye's carboxyl functionality also supports downstream conjugate handling and, in many formats, improved control over labeling chemistry and conjugate behavior.

1. Protein And Antibody Labeling

6-Carboxytetramethylrhodamine succinimidyl ester is frequently used by protein chemistry and immunochemistry teams to generate fluorescently labeled antibodies, antibody fragments, enzymes, and affinity reagents for fluorescence imaging and assay development. NHS ester reactivity enables straightforward attachment to lysine residues on biomolecules, producing stable amine-reactive conjugates that can be tracked in binding studies, target engagement experiments, and reagent characterization workflows. In practice, researchers rely on this dye for red-channel visualization and for preparing labeled bioconjugates used in microscopy-based localization and fluorescence readout assays.

2. Fluorescence Microscopy Staining

6-Carboxytetramethylrhodamine succinimidyl ester supports fluorescence microscopy workflows where covalent labeling of proteins or amine-containing biomaterials is required for cellular imaging and structural studies. Common use cases include labeling extracellular matrix components, labeling surface-associated proteins on fixed samples, and preparing fluorescent conjugates to visualize biomolecular distribution in imaging experiments. The dye's strong emission in the red-orange region helps reduce background in multi-color experiments when paired with compatible fluorophores and standard microscope filter sets.

3. Flow Cytometry Conjugate Preparation

6-Carboxytetramethylrhodamine succinimidyl ester is used in flow cytometry reagent development to prepare fluorescent conjugates that report on binding of amine-containing biomolecules to cells or to cell-associated targets. Researchers typically incorporate this dye into antibody conjugates or other lysine-rich binding reagents to enable quantitative fluorescence measurements as cells pass through the laser interrogation point. The NHS-ester labeling approach is valued for producing covalent, stable dye conjugates suitable for routine staining and comparative analysis across experimental conditions.

4. Biomaterial Surface Functionalization

6-Carboxytetramethylrhodamine succinimidyl ester is applied in biomaterials science to fluorescently tag amine-functionalized polymers, hydrogels, and surface coatings for visualization of material distribution and coating uniformity. Lab teams use the dye to create trackable material conjugates that help confirm functionalization steps, monitor coating stability during incubation, and support imaging-based characterization of engineered surfaces. This use is especially common when researchers need a robust covalent fluorescent label to follow biomaterial localization in microscopy or fluorescence imaging assays.