Receptors for native recognition of Sia. The carboxylate and diol groups of sialic acid have been exploited for recognition purposes by lanthanide ligand DTPA-bisamide compounds L1 (3,9-Bis{6-[(4,5-dihydroimidazol-2-yl)aminoethyl]-10-[2-(dihydroxyboranylphenyl)]-2-oxo-3,6,9-triazadecyl}-6-carboxymethyl-,6,9-triazaundecanedioic acid) and L2 (3,9-Bis[3-(dihydroxyboranylphenyl)-2-oxo-3,6-diazaheptyl]-6-carboxymethyl-3,6,9-triazaundecanedioic acid) bearing boronic and functional groups (L1: aminoimidazolium and L2: aminomethyl). Also, a thiourea-based synthetic receptor (2-{[3-(4-Nitrophenyl)ureido]methyl}phenylboronic acid) has been reported to show a high specificity towards Sia.
