5-(6)-Carboxyseminaphthofluorescein | CAS 151820-33-6

5-(6)-Carboxyseminaphthofluorescein is a fluorescein-derived dye featuring a carboxylic acid substituent that supports covalent attachment to amine-containing biomolecules and affinity surfaces while retaining strong green fluorescence for labeling workflows. Its fluorescein core is widely used in fluorescence microscopy and spectroscopy formats where reliable, visible-range emission is required for tracking conjugates, staining targets, and building fluorescent standards. The dye's anionic character and reactive carboxyl functionality also make it a practical component for preparing labeled reagents used in imaging and fluorescence readouts.

1. Fluorescent Protein Labeling

5-(6)-Carboxyseminaphthofluorescein is used to generate fluorescein-tagged proteins for fluorescence imaging and quantitative fluorescence assays, particularly when downstream conjugates need a stable, bright green reporter. Research groups commonly employ it to label antibodies, enzymes, and protein scaffolds for localization studies in cell biology workflows, as well as for preparing fluorescent protein conjugates used as reagents in binding and interaction assays. The carboxyl substituent enables straightforward coupling strategies to introduce the dye onto biomolecules bearing compatible nucleophiles, supporting preparation of labeled conjugates for microscopy, plate-based fluorescence measurements, and calibration materials.

2. Fluorescence Microscopy Staining

5-(6)-Carboxyseminaphthofluorescein is frequently incorporated into microscopy staining panels where fluorescein emission provides a convenient green channel for tracking labeled biomolecules and surface-associated targets. In imaging workflows, laboratories use it to visualize distribution patterns of dye-conjugated probes across fixed samples and labeled specimens, including immunofluorescence-style labeling where the dye serves as a fluorescent reporter on targeting ligands. The dye's established fluorescein photophysics and compatibility with standard fluorescence microscopes make it a practical choice for multi-label experiments that require a robust, visible-range signal.

3. Flow Cytometry Conjugates

5-(6)-Carboxyseminaphthofluorescein is used to prepare fluorescein-based staining reagents for flow cytometry experiments that quantify fluorescence intensity associated with labeled biomolecules. Typical workflows include generating dye-conjugated binding reagents for cell-surface or intracellular labeling strategies where a green fluorescent readout is required for population-level analysis. The dye's covalent attachment to biomolecule carriers supports preparation of reproducible conjugates for routine cytometry staining, enabling researchers to monitor labeling intensity distributions and track conjugate performance in assay development and method optimization.

4. Fluorescent Standards And Tracers

5-(6)-Carboxyseminaphthofluorescein is also applied as a fluorescent tracer and reference material in fluorescence assay development, where a well-characterized green dye signal helps define assay baselines and support method qualification. Many laboratories use fluorescein-derived dyes to prepare calibration standards for instrument alignment, plate reader checks, and comparative studies across labeling batches. By using a dye with established fluorescein fluorescence behavior, teams can streamline reagent evaluation for new conjugates, optimize labeling conditions for downstream probes, and support consistent fluorescence readouts in screening and analytical workflows.