Boc-Aminooxy-PEG4-NH2（Cat No.:I014713）is a bifunctional polyethylene glycol linker containing an aminooxy group protected by a Boc group on one end and a free primary amine on the other, connected through a four-unit PEG spacer. The aminooxy group enables chemoselective oxime or hydrazone ligation with aldehydes and ketones, while the Boc group provides controlled deprotection for selective functionalization. The PEG4 chain enhances solubility, flexibility, and biocompatibility while reducing steric hindrance. This versatile reagent is widely used in peptide synthesis, bioconjugation, and drug discovery for designing multifunctional biomolecular constructs.