Helixyte™ iFluor® 350 Nucleic Acid Labeling Dye is a key member of our enabling Helixyte™ nucleic acid labeling and conjugation technology. The labeling/conjugation of a tag/hapten to nucleic acids has been very challenging due to the lack of reactive moieties in nucleic acid molecules. Thymine and guanosine have been often explored for nucleic acid conjugations, e.g., photo-crosslink (to thymine by psoralens) or bromination/Ulysis labeling of guanosine. However, these existing conjugations are either tedious or require stringent conditions with low yields and are thus not suitable for routine lab use. Under the similar conditions, our Helixyte™ nucleic acid labeling and conjugation technology is much easier to use with significantly higher yield. Helixyte™ iFluor® 350 Nucleic Acid Labeling Dye provides a unique method to attach the iFluor® 350 fluorophore to nucleic acids via a simple mixing step. The labeling reagent readily reacts with the N7 of guanine to form a stable covalent bond. The labeling procedure is simple and fast with a high production yield. The separation of the labeled nucleic acids from the unreacted dye can be accomplished with a simple ethanol precipitation, a spin-column or dialysis. The resulting labeled DNA/RNA probes have bright blue fluorescence that can be easily detected with AMCA/Alexa Fluor 350 filter set. They can be used for dot, Northern and Southern blots, RNA and DNA in situ hybridization, multicolor fluorescence in situ hybridization (mFISH), comparative genome hybridization (CGH) or microarray analysis etc.