Cyanine3 phosphoramidite, 5'-terminal

Cyanine3 phosphoramidite, 5'-terminal is a Cy3-based nucleic-acid labeling building block supplied as a 5'-terminal phosphoramidite for solid-phase oligonucleotide synthesis. This reagent enables incorporation of the cyanine fluorophore at the 5' end of DNA or RNA strands, supporting fluorescence readouts in hybridization assays, sequencing-by-synthesis workflows, and fluorescence microscopy or gel-based analyses where Cy3 emission is detected. The phosphoramidite functionality is designed for routine oligonucleotide conjugate preparation, yielding fluorescent probes with defined dye placement for consistent imaging and assay development.

1. 5' Oligonucleotide Labeling

Cyanine3 phosphoramidite, 5'-terminal is used by oligonucleotide synthesis groups to generate Cy3-labeled DNA or RNA probes with the dye positioned at the 5' terminus. This placement is commonly leveraged to preserve probe performance in hybridization experiments, because the fluorophore location is fixed and does not require post-synthesis dye coupling. Researchers use the resulting 5'-Cy3 oligos in fluorescence-based characterization of nucleic acid interactions, including gel imaging to verify probe integrity, labeling consistency, and hybrid formation.

2. Fluorescent Hybridization Probes

Cyanine3 phosphoramidite, 5'-terminal supports fluorescence detection in nucleic acid hybridization workflows where Cy3 emission is monitored. Molecular biology and diagnostics research teams incorporate the 5'-Cy3 dye into single-stranded oligonucleotides used as hybridization probes for target-dependent fluorescence readouts, including microarray-style binding studies and solution-based hybridization assays. The defined 5' dye position helps standardize probe behavior across batches, which is valuable when comparing binding curves, optimizing probe concentration, or evaluating competitor oligos.

3. Fluorescence Imaging of Nucleic Acids

Cyanine3 phosphoramidite, 5'-terminal is frequently employed in fluorescence microscopy and related imaging workflows that visualize nucleic acids using fluorescently tagged oligonucleotides. Cell biology laboratories and imaging method developers use 5'-Cy3 oligos as sequence-specific staining reagents to track hybridization to complementary RNA or DNA targets in fixed samples or assay formats compatible with Cy3 excitation/emission. This reagent is also used in imaging assay development where consistent dye placement at the 5' end improves reproducibility for probe localization and signal quantitation across experimental conditions.

4. Sequencing and Fragment Analysis

Cyanine3 phosphoramidite, 5'-terminal is used to prepare Cy3-labeled oligonucleotide fragments and primers for fluorescence-based nucleic acid analysis. In research settings focused on assay development and method optimization, teams incorporate the dye at the 5' end to generate fluorescently traceable strands for readout by fluorescence-capable instrumentation such as gel documentation systems and fragment analysis workflows. The ability to build the fluorophore into the oligo during synthesis helps streamline reagent preparation for experiments that rely on fluorescent tracking of extension, ligation products, or labeled fragment populations.