Propargyl-PEG5-tetra-Ac-beta-D-galactose is a Click Chemistry-ready crosslinker containing a propargyl group and beta-D-galactose. The propargyl groups can react with azide-bearing compounds or biomolecules via copper catalyzed azide-alkyne Click Chemistry to yield stable triazole linkages. D-galactose increases solubility in aqueous media and a the selectivity of the PEGlation reaction.