A β-D-lactose ligand equipped with a biotin tag through a hydrophilic PEG3 spacer. The biotin moiety binds with high affinity to streptavidin and neutravidin, enabling straightforward immobilization on chips, in wells, or on other streptavidin/neutravidin-coated platforms. This compound provides a lactose (Galβ1-4Glc) building block for glycoconjugate synthesis and the construction of probes for galactose-recognizing proteins, including galectins and the hepatic asialoglycoprotein receptor. It is a substrate for sialyltransferases and other glycosyltransferases.