t-Boc-aminooxy-PEG6-propargyl is a bifunctional linker molecule. The propargyl group can react with azide-bearing compounds or biomolecules via copper catalyzed azide-alkyne Click Chemistry to yield a stable triazole linkage. The protected aminooxy can be deprotected under mild acidic conditions and then can react with an aldehyde.. The hydrophilic PEG spacer increases solubility in aqueous media.