Ultrasmall glyco-gold nanoparticlessynthesis optimization, characterization and applications in immune-cell targeting

Resumen

Gold nanoparticles (GNP) are hybrid materials, with excellent physicochemical characteristics, made of a gold core and a corona of organic molecules, amongst them carbohydrates. Ultrasmall GNP (nanoclusters) are usually obtained through a modified Brust-Schiffrin synthesis. The combination of glycoscience and ultrasmall GNP enables wide biotechnological and clinical applications. Using the GNP multivalency or multifunctionality properties, carbohydrates can, for instance, trigger the cluster glycoside effect required for the targeting of lectin receptors.To deliver reliable and reproducible GNP material, a tight control of the synthesis and a broad spectrum of analytical techniques are essential. To this end, the passivation step of the aqueous Brust-Schiffrin synthesis was thoroughly studied with different platforms and narrow one-parameter variations. Moreover, an extensive characterization was performed to optimize the analytical techniques, compare the data and obtain the most accurate description of the synthetized material.A novel chromatographic method of corona characterization for weak or non-UV absorbent ligands was developed using charged aerosol detection coupled with mass spectrometry (LC-CAD-MS), accompanied by a new etching protocol using tris(2-carboxyethyl)phosphine. The results were compared to those obtained by 1H NMR.A library of ¿-mannose (¿-Man) derivatives together with oligosaccharides were used to decorate the GNP through post-functionalization reactions. The different routes to achieve the ¿-Man library and functionalize the GNP were compared to find the most efficient method.Biochemical (microarray, biolayer interferometry) and biological (cell uptake) assays were performed to achieve and optimize the targeting of lectins such as DC-SIGN by Glyco-GNP. ¿-Man and, more significantly, the dimer ¿-Man1,2¿-Man were able to effectively bind to DC-SIGN and improve the specific uptake of GNP in dendritic cells. Moreover, the ability of GNP to quench fluorescence was used to screen a library of lectins with different carbohydrate specificities.