Cyanine3.5 carboxylic acid | CAS 1802928-88-6

Cyanine3.5 carboxylic acid is a cyanine-family fluorophore presented as a carboxylic acid, enabling covalent attachment to biomolecules and material surfaces through standard amide coupling or related conjugation chemistries. Its red-shifted emission makes it useful for fluorescence imaging workflows where spectral separation from green labels is advantageous, including multicolor labeling and fluorescence readouts in microscopy and assay formats.

1. Fluorescent Bioconjugation Labeling

Cyanine3.5 carboxylic acid is frequently used to generate fluorescent bioconjugates for protein labeling, peptide conjugation, and nucleic acid tagging in chemical biology workflows. Researchers typically convert the carboxylic acid into an activated coupling intermediate and then attach the dye to primary amines on antibodies, affinity ligands, enzymes, or other carrier biomolecules. The resulting conjugates are used for fluorescence imaging, binding studies, and reagent development where a cyanine dye with red-shifted emission helps reduce spectral overlap with common green fluorophores.

2. Fluorescence Microscopy Tracing

Cyanine3.5 carboxylic acid supports cellular and materials microscopy experiments that rely on bright, long-wavelength fluorescence for localization and tracking. After conjugation to targeting biomolecules or surface-reactive handles, the dye-labeled constructs are used to visualize distribution on cell surfaces, within labeled biomaterials, or across labeled biological assemblies in fluorescence microscopy. In multichannel imaging, Cyanine3.5 emission is often chosen to improve channel separation when green and far-red probes are used together.

3. Flow Cytometry Dye Conjugates

Cyanine3.5 carboxylic acid is used in flow cytometry workflows where fluorescent labeling of biomolecules enables quantitative analysis of binding and population-level readouts. Conjugated antibody or ligand reagents prepared from the dye are commonly employed to label cell-associated targets, followed by flow-based fluorescence detection to quantify staining intensity across samples. The carboxylic acid handle supports downstream conjugation strategies that integrate into established cytometry labeling pipelines, particularly when red-shifted emission helps distinguish the signal from standard green channels.

4. Fluorescent Bioassay Reagent Development

Cyanine3.5 carboxylic acid is also applied in fluorescence-based assay development, including labeling of assay components and construction of detection reagents for plate-based readouts. Dye conjugation to proteins, polymers, or other assay-relevant scaffolds enables fluorescent tracking of binding events, reagent localization, or signal generation in homogeneous and heterogeneous assay formats. In these applications, the cyanine dye's emission properties support assay designs that benefit from spectral spacing and compatibility with common fluorescence instrumentation.