Synthesis of biotinylated α-D-mannoside or N-acetyl β-D-glucosaminoside decorated gold nanoparticles: study of their biomolecular recognition with Con A and WGA Lectins.

Gold nanoparticles (NPs) functionalized with a mixed shell of well-defined biotinylated glycopolymers and polyethylene glycol (PEG) provide an effective platform for the biomolecular recognition of proteins both in solution and on surfaces. Well-defined biotinylated glycopolymers were first synthesized by the reversible addition-fragmentation chain transfer (RAFT) process. They contain two types of carbohydrate residues either N-acetyl β-D-glucosaminopyranoside (GlcNAc) or α-D-mannopyranoside (Man) as pendent groups. The biotinylated glycopolymers and polyethylene glycol were subsequently used in the in situ formation of gold glyconanoparticles via an easy photochemical process. The obtained biotinylated glyconanoparticles were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The bioavailability of the biotin and specific carbohydrate residues at the periphery of the NPs were assessed using the diffraction optic technology (DOT) system. The studies showed the accessibility of the biotin ligands for conjugation to immobilized avidin on the DOTLab biosensor. Furthermore, these avidin conjugated glyconanoparticles were found to selectively immobilize lectins. The specificity of lectin binding was dependent on the type of carbohydrate residues. As such, N-acetyl β-D-glucosaminoside decorated gold nanoparticles were found to specifically interact with wheat germ agglutinin (WGA) lectin, whereas α-D-mannoside ones were found to specifically interact with Concanavalin A (Con A) lectin.