Gold nanoparticles coated with a pyruvated trisaccharide epitope of the extracellular proteoglycan of Microciona prolifera as potential tools to explore carbohydrate-mediated cell recognition

The species-specific cell adhesion in the marine sponge Microciona prolifera involves the interaction of an extracellular proteoglycan-like macromolecular complex, otherwise known as aggregation factor. In the interaction, two highly polyvalent functional domains play a role: a cell-binding and a self-interaction domain. The self-recognition has been characterized as a Ca2+-dependent carbohydrate–carbohydrate interaction of repetitive low affinity carbohydrate epitopes. One of the involved epitopes is the pyruvated trisaccharide b-D-Galp4,6(R)Pyr-(1→4)-b-D-GlcpNAc-(1→3)-LFucp. To evaluate the role of this trisaccharide in the proteoglycan–proteoglycan self-recognition, b-D-Galp4,6(R)Pyr-(1→4)-b-D-GlcpNAc-(1→3)-a-L-Fucp-(1→O)(CH2)3S(CH2)6SH was synthesized, and partially converted into gold glyconanoparticles. These mimics are being used to explore the self-interaction phenomenon for the trisaccharide epitope, via TEM aggregation experiments (gold glyconanoparticles) and atomic force microscopy (AFM) experiments (self assembled monolayers; binding forces)