N-(m-PEG4)-N'-(PEG4-acid)-Cy5 | CAS 2107273-32-3

N-(m-PEG4)-N'-(PEG4-acid)-Cy5 is a Cy5-based, PEGylated cyanine dye designed for aqueous labeling workflows where improved solubility and reduced nonspecific interactions are beneficial. The PEG spacers and terminal carboxylic acid support downstream conjugation or coupling to biomolecules, peptides, and targeting ligands, enabling fluorescence imaging and quantitative fluorescence readouts in microscopy and assay development. Its Cy5 spectral characteristics make it commonly used for far-red fluorescence applications that benefit from reduced background in biological samples.

1. Protein And Antibody Labeling

N-(m-PEG4)-N'-(PEG4-acid)-Cy5 is frequently used by researchers to prepare far-red fluorescent protein conjugates for binding studies, immunoassays, and fluorescence-based characterization of biomolecular interactions. The PEGylated architecture helps maintain dye performance in aqueous labeling conditions and can reduce aggregation-driven background compared with less hydrophilic cyanines. The terminal acid functionality supports coupling strategies that attach the dye to proteins and antibody scaffolds used in fluorescence microscopy, plate-based assays, and flow cytometry workflows where Cy5 emission is detected.

2. Fluorescence Imaging Tracers

N-(m-PEG4)-N'-(PEG4-acid)-Cy5 is used as a labeling tracer in cellular and biomaterials imaging experiments, including experiments where dye conjugates are tracked over time to visualize distribution, uptake, or association with macromolecular constructs. The PEG spacers provide a flexible dye presentation that can reduce steric constraints when the dye is tethered to larger biomolecules or polymeric carriers. In practice, this supports preparation of fluorescent conjugates used for far-red fluorescence microscopy and imaging reagent development, particularly when minimizing nonspecific staining and maintaining water compatibility are important.

3. Bioconjugation For Targeting Ligands

N-(m-PEG4)-N'-(PEG4-acid)-Cy5 is well suited for constructing fluorescent bioconjugates where a dye-bearing ligand is used to report binding to a biomolecular recognition element or to track a functional payload in chemical biology studies. The PEGylated, acid-functional format supports coupling to targeting peptides, affinity reagents, and other ligand platforms that are subsequently used in fluorescence imaging or fluorescence readout assays. This format is commonly selected when conjugation chemistry requires a reactive handle while preserving dye solubility and reducing unwanted interactions that can complicate interpretation in complex mixtures.

4. Polymer And Nanoparticle Surface Labeling

N-(m-PEG4)-N'-(PEG4-acid)-Cy5 is used to introduce far-red fluorescence into polymeric materials and nanoparticle-based carriers for materials characterization and molecular imaging reagent development. The PEGylation and carboxylic acid functionality support attachment to surface-modified systems, enabling fluorescent labeling of hydrophilic coatings and conjugated material scaffolds used in microscopy and fluorescence spectroscopy workflows. Researchers often employ this dye to generate stable, water-compatible fluorescent materials for studying distribution, surface association, and compositional changes in engineered biomaterials.