sulfo-Cyanine7.5 maleimide

Sulfo-Cyanine7.5 maleimide is a water-soluble, thiol-reactive cyanine dye designed for fast, covalent labeling of biomolecules through maleimide-cysteine/thiol coupling. Its near-infrared fluorescence is commonly leveraged for low-background imaging and fluorescence-based tracking in aqueous biological workflows, including conjugate preparation for microscopy and assay development.

1. Protein And Peptide Labeling

Sulfo-Cyanine7.5 maleimide is frequently used by bioconjugation groups to generate fluorescent protein and peptide conjugates for fluorescence imaging and quantitative assays. Researchers typically label accessible cysteine residues on purified proteins, antibody fragments, enzymes, or synthetic peptides to create NIR fluorescent tracers for binding studies, reagent characterization, and downstream assay readouts. The sulfonated dye improves handling in aqueous buffers, supporting workflows where conjugates must remain soluble during labeling, purification, and assay incubation.

2. Antibody Conjugate Imaging

Sulfo-Cyanine7.5 maleimide supports fluorescent antibody conjugate development for microscopy and flow-based characterization of labeled binding reagents. In research settings, it is used to attach cyanine7.5 fluorophores to thiol-bearing antibody formats (for example, after controlled reduction to expose cysteines), enabling visualization of antigen-binding reagents and comparative studies of labeling density across antibody lots. The maleimide handle provides a practical route to produce NIR imaging reagents that are compatible with common fluorescence imaging platforms used for binding validation and reagent screening.

3. Cell Surface Thiol Labeling

Sulfo-Cyanine7.5 maleimide is used in cellular imaging workflows where thiol-reactive labeling is employed to tag cell-surface or membrane-associated biomolecules containing accessible cysteine residues. Laboratories often apply the reagent to generate fluorescent cell-associated tracers for microscopy-based localization studies and for monitoring relative labeling patterns across experimental conditions. The dye's near-infrared emission helps reduce interference from autofluorescence in many biological samples, which is advantageous when imaging in complex media or when background suppression is important.

4. NIR Fluorescent Tracer Conjugates

Sulfo-Cyanine7.5 maleimide is also used to prepare NIR fluorescent tracer conjugates for materials and biomolecule tracking studies, including fluorescent labeling of thiol-functionalized linkers, polymers, and biomaterial components. Researchers incorporate the dye into conjugates that are subsequently used to follow transport, distribution, or association in fluorescence imaging experiments, or to create labeled reagents for assay development. The maleimide functionality enables straightforward attachment to thiol-containing building blocks, supporting modular construction of fluorescent tracer systems used across chemical biology and biomaterials research.