Is the fluorescent oligo in the BLOCK-iT™ Basic RNAi Control Kit and Transfection Optimization Kit modified as Stealth™ RNAi?
The fluorescent oligo is modified fluorescein-labeled dsRNA. The modifications on this RNA make it a great control for transfection—causing it to localize to the nucleus in a clear and stable manner. In contrast, simply labeling siRNA with Fluorescein, results in an ill-defined punctuate pattern that which makes it difficult to distinguish whether fluorescent oligos are internalized or simply sticking to the outside of the cells.