Sulfo-Cyanine3 maleimide | CAS 1656990-68-9

Sulfo-Cyanine3 maleimide is a watersoluble cyanine dye bioconjugation reagent designed for thiol-selective labeling via its maleimide functional group. The cyanine3 fluorophore provides bright red fluorescence for tracking biomolecules and constructing fluorescent conjugates, with the sulfonated scaffold supporting aqueous labeling workflows. This reagent is commonly used to attach fluorescent tags to cysteine-containing peptides, proteins, and other thiol-bearing biomaterials for fluorescence imaging and quantitative assays.

1. Thiol-Selective Protein Labeling

Sulfo-Cyanine3 maleimide is used to fluorescently tag proteins and peptides through maleimide-mediated coupling to accessible thiols, enabling microscopy and plate-based fluorescence readouts in chemical biology and biomaterials research. Researchers often apply it to label purified proteins for localization studies, to generate fluorescent standards for assay development, or to prepare labeled affinity reagents for downstream binding experiments. The sulfonated dye format supports straightforward aqueous conjugation conditions and helps maintain labeling performance in buffer-based workflows.

2. Fluorescent Probe Construction

Sulfo-Cyanine3 maleimide serves as a practical building block for assembling cyanine3-based fluorescent probes and conjugates where a thiol handle is available on the probe scaffold. Common use cases include preparing labeled targeting ligands, constructing multicomponent imaging reagents, and generating fluorescent conjugates for monitoring binding events in solution or on surfaces. By providing a reactive dye moiety that can be installed onto thiol-functional biomolecules, it streamlines probe development for fluorescence imaging platforms that rely on cyanine3 excitation and emission.

3. Biomaterial Surface Functionalization

Sulfo-Cyanine3 maleimide is frequently incorporated into workflows that create fluorescently labeled biomaterial surfaces and coatings by coupling the dye to thiol-functionalized polymers, linkers, or surface chemistries. Materials scientists use cyanine3 labeling to visualize coating uniformity, track surface-mediated interactions, and support fluorescence-based characterization of engineered interfaces. In these applications, the water-soluble sulfonated dye helps maintain labeling practicality for aqueous surface modification and subsequent imaging or quantification.

4. Cell Labeling For Imaging Studies

Sulfo-Cyanine3 maleimide is used in cellular fluorescence labeling experiments where thiol-containing biomolecules or thiol-reactive labeling strategies are employed to introduce a cyanine3 signal for imaging. Researchers apply the dye-conjugated reagents to visualize distribution patterns of labeled biomolecular components in fixed or prepared samples, supporting workflow development for fluorescence microscopy and related imaging assays. The maleimide chemistry enables installation of the fluorophore onto thiol-bearing targets used as imaging reporters in cell biology tool development.