A β-D-N-acetyllactosamine (LacNAc) ligand equipped with a free thiol through a hydrophilic PEG3 spacer. The thiol reacts with maleimides to form stable thioether conjugates or with other thiols to form disulfide bonds; it is also compatible with thiol-gold chemistry for surface immobilization. This compound provides an N-acetyllactosamine (LacNAc; Galβ1-4GlcNAc) building block, a core disaccharide of N- and O-glycans and a galectin ligand; it is a substrate for sialyltransferases and fucosyltransferases, enabling extension to sialylated and fucosylated structures.