Cyanine5.5 carboxylic acid is a near-infrared fluorophore bearing a reactive carboxyl group suitable for conjugation with biomolecules. Researchers use it to study long-wavelength fluorescence behavior, energy transfer, and environmental sensitivity. Its extended π-system supports imaging-focused biophysical work.
CAT No: R2498
CAS No:1144107-80-1
Synonyms/Alias:Cyanine5.5 dye;Cyanine5.5 carboxylic acid;Cy5.5-cooh;1144107-80-1;1449661-34-0;BCP30060;
Cyanine5.5 carboxylic acid is a synthetic organic dye belonging to the cyanine family, characterized by its extended conjugated structure and strong absorption and emission in the near-infrared (NIR) region. As a functionalized derivative bearing a carboxylic acid group, this compound is highly valued for its ability to be covalently attached to biomolecules, polymers, or surfaces through amide bond formation or other coupling chemistries. Its photophysical properties, including high molar absorptivity, excellent fluorescence quantum yield, and photostability, make it an essential tool in advanced fluorescence applications. The compound's unique spectral characteristics facilitate multiplexed detection, deep-tissue imaging, and sensitive assay development, supporting a broad range of biochemical and analytical research initiatives.
Fluorescent labeling: Cyanine5.5 carboxylic acid is extensively used as a fluorescent labeling reagent for biomolecules such as proteins, peptides, nucleic acids, and antibodies. The carboxyl functional group enables efficient conjugation via carbodiimide-mediated coupling reactions, creating stable amide linkages with primary amines. This labeling approach allows researchers to track the localization, interactions, and dynamics of target molecules in complex biological systems using fluorescence microscopy, flow cytometry, or in vivo imaging platforms. The NIR emission profile of the dye minimizes background autofluorescence and enhances signal-to-noise ratios, particularly in biological tissues.
Optical imaging: The compound's strong absorption and emission in the near-infrared region make it particularly well-suited for optical imaging applications, including in vivo imaging of small animals, tissue samples, or cellular models. NIR fluorophores such as this one penetrate biological tissues more effectively than visible-light dyes, enabling deeper imaging with reduced light scattering and absorption. Researchers utilize these properties to visualize molecular events, monitor biodistribution, and study pharmacokinetics in preclinical models, thereby gaining insights into biological processes at the whole-organism or tissue level.
Multiplexed detection assays: Cyanine5.5 derivatives are valuable in multiplexed detection strategies, where several spectrally distinct fluorophores are used simultaneously to monitor multiple analytes or targets within a single experiment. The well-separated excitation and emission maxima of this dye allow for clear discrimination from other commonly used fluorophores, reducing spectral overlap and crosstalk. This capability is critical in applications such as high-content screening, immunoassays, and gene expression profiling, where accurate quantification of multiple signals is essential for robust data interpretation.
Fluorescence resonance energy transfer (FRET) studies: The spectral properties of this cyanine dye make it a suitable acceptor or donor in FRET-based assays, which are widely employed to investigate molecular interactions, conformational changes, and proximity relationships in biological systems. By pairing it with compatible fluorophores, researchers can design sensitive FRET probes to monitor dynamic biochemical events in real time. The use of NIR FRET pairs also extends the applicability of these assays to settings with high background fluorescence or where deep tissue penetration is required.
Surface and material functionalization: Beyond direct biomolecular labeling, Cyanine5.5 carboxylic acid serves as a versatile building block for the functionalization of materials, nanoparticles, and biosensor surfaces. Its carboxyl group provides a convenient handle for covalent attachment to aminated substrates, enabling the creation of fluorescently tagged materials for bioanalytical devices, diagnostic platforms, or nanotechnology research. Incorporation of this dye into surfaces or particles allows for sensitive optical detection, tracking, and quantification in a wide array of analytical and materials science applications.
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