A Neu5Acα2-6LacNAc trisaccharide (Neu5Acα2-6Galβ1-4GlcNAc) 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. Neu5Acα2-6LacNAc is a ligand for Siglecs and for influenza hemagglutinin, particularly the human-adapted strains that preferentially recognize α2-6-linked sialic acids. This probe can be used as a soluble inhibitor or immobilized on plates or sensors to investigate binding. Neu5Acα2-6LacNAc is also a substrate for sialidases, enabling its use in enzyme activity assays and in studies of sialic acid turnover.