study of the multivalent carbohydrate/protein interactions on silicon biosensors

Abstract : Specific carbohydrate/protein interactions play an important role in numerous physiological and pathological processes. Silicon-based biosensors have been envisaged for studying such interactions here. In a first approach, a multistep functionalization strategy was established on crystalline silicon via robust covalent Si-C bonds to incorporate oligo(ethylene glycol) units and generate a glycan-terminated monolayer by “click” chemistry. The functionalization process was carefully characterized by IR-ATR, AFM and XPS, leading to the formation of highly compact organic monolayers. The as-fabricated glycan-terminated surface showed good antifouling property towards non-specific lectins and excellent selectivity towards specific lectins. By using quantitative IR-ATR analysis and numerical simulation, we demonstrated the importance of the surface concentration of glycans to favor the multivalent binding of the glycan ligands on the surface with the specific lectins. In a second approach, the amorphous silicon-carbon alloy thin films coated on gold nanoparticles were used as the substrate for the elaboration of glycan microarray. Fluorescence imaging was used for the recognition specificity of the glycans clicked on the surface with the dye-labeled lectins. By optimizing the distance between the fluorophore and the nanoparticles, best localized surface plasmon resonance (LSPR)-enhanced fluorescence was achieved to improve the microarray sensitivity with a limit of detection at the picomolar level.
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Jie Yang. study of the multivalent carbohydrate/protein interactions on silicon biosensors. Chemical Sciences. Ecole polytechnique X, 2014. English. ⟨tel-01086711⟩

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