Cy5.5 NHS ester (potassium salt) | CAS 910482-46-1

Cy5.5 NHS ester (potassium salt) is a reactive cyanine dye designed for covalent fluorescent labeling of primary amines via NHS ester chemistry. Its Cy5.5 spectral profile supports far-red fluorescence workflows where reduced background and deep-tissue compatibility are often advantageous for microscopy and fluorescence-based assays. Researchers use this dye to prepare fluorescent conjugates for labeling proteins, peptides, and other amine-containing biomolecules, as well as for building imaging reagents and standards.

1. Protein And Antibody Labeling

Cy5.5 NHS ester (potassium salt) is widely used in fluorescence labeling of proteins and antibody-based reagents for immunofluorescence, western blotting workflows, and fluorescence imaging studies. Because the NHS ester reacts efficiently with lysine side-chain amines and N-termini, it enables preparation of labeled conjugates for tracking binding interactions, monitoring reagent distribution, and generating fluorescent detection handles in assay development. Typical users include cell biology and analytical chemistry groups preparing fluorescent immunoprobes, as well as core facilities producing labeled antibodies for microscopy and imaging pipelines.

2. Fluorescence Microscopy Tracing

Cy5.5 NHS ester (potassium salt) supports far-red fluorescence microscopy applications where amine-reactive labeling is needed to visualize biomolecules in fixed-cell or in vitro imaging contexts. Labeled proteins, peptides, or extracellular matrix components can be used to trace localization patterns, follow uptake or binding to immobilized targets, and map distribution within experimental samples. Imaging teams often select Cy5.5 labeling to align with common far-red filter sets and to reduce interference from autofluorescence when imaging complex biological backgrounds.

3. Flow Cytometry Dye Conjugates

Cy5.5 NHS ester (potassium salt) is used to generate fluorescent conjugates for flow cytometry panels that require far-red emission for multiplexing or background reduction. By covalently attaching the dye to amine-containing targeting proteins or detection reagents, laboratories can create stable fluorescent probes for cell-surface staining and binding readouts in research cytometry workflows. Assay developers and immunophenotyping teams use Cy5.5-labeled conjugates to support multicolor experiments where spectral separation from green and orange channels improves panel design flexibility.

4. Fluorescent Standards And Calibration

Cy5.5 NHS ester (potassium salt) is also used to prepare fluorescent labeling standards and calibration reagents for quantitative fluorescence measurements. Labeled proteins and defined amine-reactive conjugates can serve as reference materials for instrument setup, gating consistency, and method development in fluorescence imaging and plate-based readouts. Analytical chemistry and assay development groups often rely on dye-conjugated standards to validate labeling consistency across experiments and to support reproducible fluorescence quantification workflows.