Quasar 570 NHS | CAS 771456-48-5

Quasar 570 NHS is an NHS ester-functionalized red/orange fluorescent labeling reagent designed for efficient amide bond formation with primary amines on proteins, peptides, and other amine-containing biomolecules. Its strong fluorescence in the visible range makes it a practical donor fluorophore for fluorescence-based assays and imaging workflows where robust conjugation and convenient dye handling are required.

1. Protein Fluorescent Labeling

Quasar 570 NHS is widely used by bioconjugation and fluorescence-imaging labs to generate fluorescently labeled proteins for microscopy, spectroscopy, and assay development. Researchers typically apply it to antibodies, enzymes, and affinity reagents to introduce a stable dye tag through NHS-ester coupling to lysine residues or N-terminal amines, enabling visualization of binding interactions, tracking of biomolecule localization, and construction of fluorescent standards for method development. The amine-reactive NHS functionality supports straightforward conjugate preparation for downstream use in fluorescence readouts without requiring additional activation steps beyond the conjugation workflow.

2. FRET Donor Construction

Quasar 570 NHS is frequently selected as a donor fluorophore building block in FRET-based assay design when a visible red/orange donor is needed to pair with an appropriate acceptor dye. In these workflows, the NHS ester enables convenient conjugation of Quasar 570 to proteins or peptides used as FRET sensor components, allowing researchers to monitor distance-dependent energy transfer in labeled constructs such as proximity assays, binding/interaction studies, and engineered reporter systems. Signal control is achieved by the donor-acceptor spectral relationship and the labeled biomolecular architecture, making Quasar 570 NHS a useful reagent for constructing donor-labeled reagents that integrate into established FRET assay formats.

3. Flow Cytometry Reagent Development

Quasar 570 NHS supports fluorescent labeling strategies used in flow cytometry and cell-based screening workflows where an amine-reactive dye is required to tag antibodies or other targeting proteins. By conjugating Quasar 570 to affinity reagents, researchers can generate cell-surface or extracellular labeling reagents for fluorescence-based phenotyping, binding studies, and multiplex assay development with spectrally compatible detection channels. The NHS ester chemistry helps streamline reagent preparation for consistent dye loading on protein binders, which is important for reproducible staining workflows during assay optimization and instrument method development.

4. Biomaterial Surface Functionalization

Quasar 570 NHS is also used to fluorescently functionalize amine-bearing biomaterials and surfaces for imaging and materials characterization. Researchers incorporate the dye into polymer coatings, bead surfaces, or other amine-containing substrates to create fluorescent markers that enable tracking of material distribution, coating uniformity, and surface association in microscopy and imaging experiments. Because the reagent targets primary amines, it is commonly leveraged when the material platform presents accessible amine groups, allowing formation of stable dye-material linkages that support subsequent imaging and analytical evaluation of surface-modified constructs.