Used in solid-phase oligonucleotide synthesis, particularly in the preparation of DNA probes and primers. Its primary role is to introduce a polyethylene glycol (PEG) spacer with a terminal protected hydroxyl group, enabling conjugation with other molecules such as fluorophores, biotin, or peptides. The TBdms (tert-butyldimethylsilyl) group protects the hydroxyl during synthesis, while the phosphoramidite moiety allows for efficient coupling to the growing DNA chain. The β-cyanoethyl group stabilizes the phosphate intermediate and prevents side reactions. After synthesis, the protecting groups are removed under standard deprotection conditions, freeing the hydroxyl for downstream conjugation. This reagent is especially valuable in diagnostic assays, labeled probes, and functionalized nucleic acids for research and therapeutic applications.