Cyanine3 carboxylic acid (chloride) | CAS 1144107-76-5

Cyanine3 carboxylic acid (chloride) is a reactive cyanine dye building block designed for fluorescent labeling workflows. As an activated carboxylic acid derivative, it supports formation of stable dye conjugates with amine-containing biomolecules and labeling handles used in fluorescence microscopy, imaging, and assay development. Cyanine3 fluorophores are commonly selected for red/orange fluorescence readouts, enabling multiplex-friendly experimental designs when paired with appropriate filter sets and reference dyes.

1. Protein Conjugation Labeling

Cyanine3 carboxylic acid (chloride) is frequently used by researchers to generate fluorescent protein conjugates for imaging and quantitative fluorescence assays. In typical labeling workflows, the activated dye is coupled to lysine-rich proteins or other amine-bearing targets to produce dye-tagged antibodies, enzymes, or purified protein standards. These Cyanine3 conjugates are then used for cellular and biochemical studies where a bright red/orange emission is advantageous, including tracking binding interactions on membranes, monitoring protein distribution in microscopy experiments, and building fluorescent reagents for plate-based readouts.

2. Antibody And Affinity Reagent Imaging

Cyanine3 carboxylic acid (chloride) supports fluorescent labeling of affinity reagents used in immunostaining and binding assays. By coupling the dye to antibody frameworks or other amine-functional recognition molecules, users can construct imaging reagents for fluorescence microscopy and flow cytometry-style workflows where red/orange emission is detected through standard optical filters. This application is especially common in assay development laboratories that need consistent dye-to-protein conjugation for reproducible staining intensity across experiments, including characterization of antigen binding, secondary reagent performance, and fluorescence-based binding curves.

3. Fluorescent Nucleic Acid Tagging

Cyanine3 carboxylic acid (chloride) is also used to prepare Cyanine3-labeled oligonucleotides when nucleic acid constructs include accessible primary amines or are engineered with amine-containing linkers. Researchers incorporate these labeled strands into hybridization studies, fluorescence-based nucleic acid assays, and probe construction for microscopy-based localization of nucleic acid targets. The activated dye form helps streamline preparation of fluorescent nucleic acid reagents used as readout reporters in nucleic acid analysis workflows where a cyanine dye emission in the red/orange range is compatible with common imaging systems.

4. Fluorescent Standards And Calibration Reagents

Cyanine3 carboxylic acid (chloride) is employed to generate dye-labeled calibration materials and fluorescent standards used to support experimental quantification. Laboratories use Cyanine3 conjugates to verify instrument alignment and filter performance, normalize staining intensity across imaging sessions, and create reference materials for method development in fluorescence assays. Because cyanine dyes are widely used in fluorescence instrumentation, Cyanine3-labeled standards help teams maintain consistent measurement conditions when comparing experiments conducted on different days, different detector settings, or different reagent batches.