IRDye® 750 NHS Ester | CAS 1364441-80-4

IRDye® 750 NHS Ester is a near-infrared fluorescent dye designed for amine-reactive bioconjugation using an NHS ester functional group. Its far-red emission is commonly leveraged to reduce background in fluorescence imaging workflows while maintaining compatibility with standard NIR detection systems. Researchers use this reagent to prepare antibody, protein, and peptide conjugates as well as labeling reagents for microscopy, imaging, and quantitative fluorescence assays.

1. Antibody Fluorescent Labeling

IRDye® 750 NHS Ester is frequently used by antibody and immunoassay developers to generate IRDye® 750-labeled secondary antibodies, affinity reagents, and immunoconjugates for fluorescence-based binding studies. The NHS ester reacts with accessible lysine residues on proteins, enabling straightforward preparation of labeled antibodies for imaging of target binding on membranes, in fixed samples, or in assay formats where far-red detection is advantageous. Typical users include academic core facilities and assay development groups building NIR fluorescence readouts for protein interaction studies and conjugate-based reagent screening.

2. Protein And Peptide Conjugation

IRDye® 750 NHS Ester supports preparation of fluorescent protein and peptide conjugates for molecular imaging reagent development and biochemical characterization of biomolecules. Because the dye is reactive toward primary amines, it is commonly used to label carrier proteins, enzymes, affinity tags, and research peptides used as imaging handles or assay components. This labeling approach is widely adopted in workflows that require a stable fluorescent reporter for quantitative fluorescence measurements, including conjugate tracking during purification, binding assays, and downstream method development.

3. Fluorescence Imaging Reagents

IRDye® 750 NHS Ester is used to construct NIR fluorescence imaging reagents for microscopy and gel-based visualization where reduced spectral interference from autofluorescence is beneficial. Researchers label biomolecular targets or assay components with the dye to enable visualization of localization and distribution in experimental systems monitored with far-red/NIR-capable imaging instruments. This includes applications such as fluorescent tracking of labeled biomolecules in research samples, visualization of conjugation outcomes after purification, and preparation of imaging-compatible probes for workflow optimization in chemical biology and biomaterials studies.

4. Quantitative Fluorescence Assays

IRDye® 750 NHS Ester is also applied in fluorescence assay development where a bright, far-red reporter is used to quantify binding, labeling efficiency, or reagent performance. Conjugates prepared from this NHS ester are commonly incorporated into assay reagents for measuring fluorescence intensity changes associated with target binding or separation steps, including plate-based readouts and fluorescence imaging of assay endpoints. Teams in chemical biology and analytical reagent development use the dye to standardize fluorescent labeling of proteins and to support reproducible fluorescence measurements across experimental batches.