Spherical GNPs (20nm) were synthesized using sodium citrate as a reducing agent, based on a well-established procedure 54 (link), 56 (link). GNPs were conjugated to MDDA linker (12-mercaptododecanoic acid, Sigma) then coated with D-(รพ)-glucosamine hydrochloride (Sigma), due to its stability and high cell-uptake rate.