Self-Assembly Of Carbohydrate-Functionalized Gold Nanoparticle Composites Via Lectin Templates

The unique structure produced by biological systems provides inspiration for the fabrication of functional materials. Proteins themselves are nanoscopic entities as well as can be used as useful nanomaterial components possessing novel properties. In addition to their exquisite features, they are obtained easily from the natural sources. There are a number of examples which employ viruses and protein assemblies for the design of new functional materials. Freeman and co-workers at Tel Aviv University have shown the formation of the predesigned diamondlike protein crystals using the self assembly of a tetrahedral letin. This strategy can be applied for the controlled fabrication of new three-dimensional protein lattices and scaffolds. Rotello and co-workers at the University of Massachusetts demonstrated the controlled assembly of protein-nanoparticle composites via protein surface recognition. These protein-mediated assemblies are also important tools for the detection of biomolecules as well as for the manufacturing of functional nanomaterials with their unique properties. Herein, we report the use of the lectin protein for the spontaneous self-assembly of carbohydratefunctionalized gold nanoparticles. We envisage the precise control over the spatial arrangements of carbohydrate-functionalized gold nanoparticles using the specific carbohydrateprotein interaction. This interaction plays a crucial role in a wide variety of intercellular processes in our nature. Gold nanoparticles were suggested as excellent fluorescence quenchers. In this report, we have observed the recognition process via quantitative fluorescence quenching experiments by monitoring of the fluorescence of TritcConcanavalin A (Con A) as the addition of the nanoparticles. Self-assembly process was observed using qualitative TEM, dynamic light scattering technique as well. We observed the aggregation process can be reversed by the addition of free mannose sugar which was not observed by the addition of galactose.