IRDye® 750 Maleimide

IRDye® 750 Maleimide is a near-infrared (NIR) fluorescent labeling reagent built on the IRDye® 750 fluorophore scaffold and equipped with a maleimide functional group for efficient conjugation to thiols. In fluorescence imaging and fluorescence-based assays, the resulting thioether-linked conjugates provide deep tissue-compatible signal collection and reduced background relative to visible dyes, making the reagent widely used for molecular labeling workflows that benefit from NIR detection. The maleimide handle enables straightforward preparation of fluorescent conjugates from reduced biomolecules, peptides, antibodies, and thiol-functionalized materials.

1. Protein And Antibody Labeling

IRDye® 750 Maleimide is commonly used to generate NIR fluorescent antibody conjugates and protein labeling reagents for imaging and analytical characterization. Researchers typically start from thiol-containing proteins (for example, reduced disulfide bonds or engineered cysteine residues) and use the maleimide group to form stable thioether conjugates, enabling consistent labeling for fluorescence microscopy, optical imaging instrumentation, and assay development where NIR readout is advantageous. This reagent is also frequently employed to prepare labeled secondary reagents and binding partners for multicomponent staining panels.

2. Peptide and Biomolecule Conjugation

IRDye® 750 Maleimide supports fluorescent tagging of peptides, oligonucleotide-associated biomolecules, and other thiol-bearing ligands used in molecular imaging reagent development. In chemical biology workflows, the maleimide functionality is leveraged to attach the IRDye® 750 fluorophore to reduced biomolecule fragments, yielding conjugates for binding studies, tracer construction, and fluorescence-based quantification. The NIR emission of the IRDye® 750 label helps researchers monitor labeled constructs in complex mixtures where visible-channel background can be limiting.

3. Thiol-Functionalized Surface Modification

IRDye® 750 Maleimide is used to fluorescently functionalize thiol-presenting surfaces and biomaterials, including polymer coatings and hydrogel systems designed for imaging readouts. By reacting with thiol groups on surface-modified substrates, the reagent enables incorporation of an NIR fluorescent tag into engineered materials used for localization studies, material tracking, and fluorescence-based characterization of surface chemistry. This labeling approach is particularly relevant when researchers need a robust, covalent attachment that supports optical readout under NIR-compatible detection systems.

4. NIR Imaging Assay Reagents

IRDye® 750 Maleimide is frequently incorporated into fluorescence assay development workflows that rely on NIR detection, such as in vitro binding assays and fluorescence quantification of labeled biomolecular reagents. Conjugates prepared from thiol-containing partners are used as fluorescent reporters to track binding, immobilization, or distribution in assay formats compatible with NIR-capable plate readers or imaging systems. The maleimide-based conjugation strategy helps researchers produce defined fluorescent reagents for standardized assay comparisons and multistep labeling pipelines where a stable NIR fluorophore is required.