Cy5.5-NHS ester tetrafluoroborate | CAS 2375105-86-3

Cy5.5-NHS ester tetrafluoroborate is a reactive Cy5.5 fluorophore NHS ester designed for efficient covalent labeling of primary amine-containing biomolecules under standard fluorescence labeling workflows. Its far-red emission supports low background imaging in microscopy and fluorescence-based assays, while the NHS ester enables straightforward conjugate preparation for protein, antibody, peptide, and other amine-functional targets. Researchers use it to generate fluorescent conjugates for molecular imaging reagent development, assay readouts, and labeling controls.

1. Protein And Antibody Labeling

Cy5.5-NHS ester tetrafluoroborate is widely used to prepare fluorescent protein conjugates for binding studies, immunofluorescence reagent development, and fluorescence-based bioassays. The NHS ester reacts with lysine side-chain amines and N-termini, enabling labeling of antibodies, antibody fragments, enzymes, and other amine-rich proteins used as detection reagents or assay components. Far-red Cy5.5 emission is particularly valued when background fluorescence from biological matrices or assay buffers can otherwise obscure signal.

2. Fluorescence Microscopy Imaging

Cy5.5-NHS ester tetrafluoroborate supports cellular and biomaterial fluorescence microscopy workflows where far-red channels improve visualization and multiplexing flexibility. Labeled proteins and affinity reagents generated from this dye are commonly used for imaging cell-surface targets, tracking labeled biomolecules in fixed or permeabilized samples, and mapping fluorescence distribution in labeled material systems. The dye's NHS-ester chemistry helps integrate labeling into established immunostaining and imaging reagent preparation pipelines.

3. Flow Cytometry Labeling Reagents

Cy5.5-NHS ester tetrafluoroborate is used to build far-red flow cytometry labeling reagents by converting amine-bearing antibodies or proteins into fluorescent conjugates compatible with standard cytometer detection channels. In research labs, this enables quantitative single-cell readouts for marker expression, binding assays, and fluorescence-based characterization of labeled biomolecules. The covalent NHS-ester labeling approach supports robust reagent preparation for consistent staining across experiments.

4. Fluorescent Tracer Conjugates

Cy5.5-NHS ester tetrafluoroborate is also applied to prepare fluorescent tracer conjugates used in molecular imaging reagent development and fluorescence tracking experiments. By labeling amine-functional biomolecules such as peptides, protein scaffolds, and other primary-amine-containing reagents, researchers generate far-red probes for monitoring distribution, uptake, and binding behavior in assay systems where fluorescence readout is the primary measurement. This use is common in platform development for fluorescence imaging reagents and labeled standards.