Cyanine7 maleimide

Cyanine7 maleimide is a reactive cyanine dye designed for thiol-directed conjugation, combining a near-infrared Cy7 fluorophore with a maleimide group that forms stable thioether linkages with sulfhydryl-containing biomolecules. Its long-wavelength emission supports deep-tissue-compatible fluorescence imaging workflows and low-background optical readouts in microscopy and fluorescence-based assays. Researchers commonly use it to generate fluorescently labeled proteins, peptides, and other thiol-functional constructs for bioconjugation and molecular imaging reagent development.

1. Thiol Bioconjugation Labeling

Cyanine7 maleimide is used to label cysteine-containing proteins, peptides, and antibody fragments through thiol-reactive conjugation, enabling fluorescent tracking of biomolecules in chemical biology and materials research. In practice, it is frequently employed to prepare fluorescent conjugates for binding and uptake studies, receptor/ligand interaction experiments, and labeling of affinity reagents where a near-infrared reporting dye improves visualization over visible fluorophores. The maleimide handle allows straightforward incorporation into downstream probes while preserving the biomolecule's native function when mild labeling conditions are used.

2. Fluorescence Microscopy Imaging

Cyanine7 maleimide supports fluorescence microscopy workflows that benefit from Cy7's red-shifted emission, including imaging of labeled biomolecules in cultured cells and in vitro biological preparations. It is commonly incorporated into imaging reagents where thiol chemistry is used to attach the fluorophore to targeting peptides, enzyme substrates, or surface-associated biomaterials, allowing researchers to visualize spatial localization and trafficking patterns with reduced spectral interference from autofluorescence. This labeling strategy is also used for multicolor experiments where Cy7 provides a distinct spectral channel for imaging instrumentation that supports near-infrared detection.

3. Flow Cytometry Fluorescent Tagging

Cyanine7 maleimide is applied to generate fluorescently tagged biomolecules for flow cytometry staining and fluorescence readouts, particularly when a near-infrared dye channel is available on the instrument. Researchers use thiol-directed conjugation to prepare Cy7-labeled antibodies, ligands, or other thiol-bearing reagents for cell-surface or cell-associated labeling studies, enabling quantitative comparisons across experimental conditions. The dye's bright Cy7 emission supports detection in single-cell analysis formats where careful control of labeling stoichiometry and background staining is required.

4. Molecular Imaging Probe Construction

Cyanine7 maleimide is widely used as a fluorescent payload for constructing molecular imaging reagents that require thiol-reactive attachment to targeting scaffolds or imaging moieties. In molecular imaging and fluorescence-based assay development, it is employed to create Cy7-labeled conjugates such as fluorescent probes for binding studies, reporter constructs for biomaterial interactions, and labeling reagents for tracking probe distribution in complex samples. The combination of maleimide reactivity and Cy7 fluorescence enables rapid incorporation of the fluorophore into probe architectures built from sulfhydryl-functional components.