A lipoic acid-tetra(ethylene glycol)-α-1-manno-α-1,2-biose (abbreviated as LA-EG4-DiMan)-based multifunctional glycan ligand was synthesised via our established procedures. We have chosen α-1manno-α-1,2-biose (DiMan) as the target glycan because it is relatively easy to synthesise. Moreover, a polyvalent display of DiMan on GNPs has been shown to give stronger MLGI affinities with DC-SIGN than some more complex (oligo)mannosides. The LA-EG4-DiMan ligand was designed to contain three unique functional domains: a lipoic acid (LA) group to provide strong chelative binding to the GNP surface by forming 2 strong Au-S bonds; a flexible, hydrophilic tetra(ethylene glycol) (EG4) linker to promote high stability, water solubility, and excellent resistance against non-specific interactions and adsorptions (ensuring results are due to specific interactions only); and a terminal α-1-manno-α-1,2-biose group to afford specific binding with DC-SIGN/R. The LA-EG4-DiMan ligand was synthesised by Cu-catalysed click chemistry between a LA-EG4-acetylene linker and N3-EG2-DiMan, and purified by using a P2 biogel column as reported previously. Details of the ligand synthesis and purification procedures and its spectroscopic characterisation were provided in the SI, Fig. .