Cyanine5.5 carboxylic acid | CAS 1144107-80-1

Cyanine5.5 carboxylic acid is a near-infrared cyanine dye supplied in the carboxylic acid form, enabling covalent incorporation into labeling constructs through amide/ester-forming coupling workflows. Its excitation/emission in the far-red to near-infrared region makes it a widely used fluorescence tag for imaging and quantitative fluorescence readouts in biochemical and materials research, where reduced background from tissue autofluorescence is often advantageous.

1. Protein And Antibody Labeling

Cyanine5.5 carboxylic acid is frequently used to generate fluorescently labeled proteins, antibodies, and affinity reagents for fluorescence imaging and binding studies. Researchers couple the dye to primary amines on biomolecules to produce stable conjugates for fluorescence microscopy, plate-based fluorescence assays, and fluorescence-based binding characterization. The far-red spectral window supports multiplex-friendly workflows when paired with spectrally distinct fluorophores, and the dye's carboxyl functionality supports design of dye-to-biomolecule conjugates that retain strong optical performance for quantitative experiments.

2. Fluorescence Microscopy Tracing

Cyanine5.5 carboxylic acid is commonly incorporated into microscopy labeling strategies for tracking biomolecule localization and distribution in fixed samples and labeled materials. Imaging workflows often rely on covalent conjugates to reduce dye loss during washing steps, enabling visualization of labeled targets in multi-step staining protocols. Because the dye emits in the far-red/near-infrared range, it is frequently selected for fluorescence microscopy experiments where background suppression and deeper signal collection are important for clear spatial readouts.

3. Oligonucleotide And Probe Conjugates

Cyanine5.5 carboxylic acid is used to prepare fluorescent oligonucleotide conjugates for nucleic acid analysis and probe-based fluorescence workflows. By attaching the dye to nucleic acid building blocks or to oligonucleotide-reactive linkers, researchers create labeled DNA/RNA probes for hybridization readouts, nucleic acid tracing, and fluorescence-based characterization of nucleic acid interactions. The dye's spectral properties support sensitive optical detection using standard fluorescence instrumentation configured for far-red channels, enabling robust readouts in gel imaging and plate formats.

4. Polymer to Biomaterial Labeling

Cyanine5.5 carboxylic acid supports fluorescence labeling of polymers, hydrogels, and biomaterial surfaces where covalent dye incorporation is needed for durable imaging and tracking. Materials scientists use dye-functionalized conjugates to visualize coatings, diffusion/penetration behavior, and labeled biomolecule immobilization on engineered substrates. The carboxylic acid form is leveraged to design dye-bearing materials that can be integrated into composite systems for fluorescence microscopy and quantitative fluorescence measurements during material characterization.