The carbohydrates galactose and 3-sulfogalactose, found on sphingolipids in myelin, interact with each other via a carbohydrate–carbohydrate interaction (CCI). In oligodendrocytes, this interaction triggers a signaling cascade resulting in cytoskeletal rearrangements and reorganization of glycolipids and proteins at the cellular surface. These rearrangements can also be triggered by synthetic multivalent glycoconjugates. In this report, we describe the synthesis of glycan-coated silica nanoparticles and their subsequent binding to cultured oligodendrocytes and purified myelin. Fluorescent silica nanoparticles with an azidosiloxane-derived outer shell were functionalized with carbohydrates using the copper-promoted azide–alkyne cycloaddition reaction. The carbohydrate–carbohydrate interaction between galactose and 3-sulfogalactose was examined by measuring the binding of 3-sulfogalactose-containing nanoparticles to galactolipids that had been immobilized in a multiwell plate. Particle aggregation mediated by CCI was observed by TEM. The interaction of the particles with oligodendrocytes and purified myelin was examined using fluorescence microscopy, providing direct evidence for binding of galactose and 3-sulfogalactose-coated nanoparticles to oligodendrocytes and myelin fragments.

A mild method for functionalization of gold nanoparticles is reported. The reactions of azide functionalized nanoparticles with propynoic acid derivatives provide triazole functionalized nanoparticles under very mild reaction conditions. Characterization of the nanoparticle-bound triazoles using 1H and 13C NMR spectroscopy indicates that both the 1,4 and 1,5 triazole regioisomers are formed on the nanoparticle surface.

This paper describes the preparation of cross-linked polynorbornene coated gold nanoparticles. The polymer was grown radially from the particle surface using a ring opening metathesis polymerization of norbornene and an electrophilic norbornene ester, which was cross-linked using a variety of diamines. The stability of the cross-linked nanoparticles toward oxidative etching by cyanide was evaluated. The rate of etching decreases as diamines with fewer degrees of conformational freedom are used as cross-linkers. The distance of the cross-linking block from the nanoparticle surface was systematically varied. Nanoparticles with the cross-linked block furthest from the surface were etched most slowly. This is suggested to arise as a result of the polymers adopting a mushroom conformation when the cross-linking block is close to the particle surface, while more distal cross-linking results in more rigid polymer chains that are less permeable to the cyanide etchant. These results provide new insight into how fine-tuning the polymer cross-linking architecture can modulate nanoparticle stability.