Preparation of efficient magnetic biosorbents by clicking carbohydrates onto graphene oxide

In this work, hydrophilic graphene nanosheets (GNS) and the related magnetic nanocomposites were prepared by first tethering alkyne-functionalized graphene oxide (GO) with azide-modified glucose followed by deposition of Fe3O4 nanoparticles on the functionalized GNS. For the preparation of nanohybrids, two approaches were designed: in the first one, after chlorination of GO with thionyl chloride, GO was reacted with propargyl alcohol and subsequently clicked with azide-glucoside. The resulted sweet GNS were easily dispersed in water and stable for 2 weeks. In the second approach, GO was functionalized with 3,4,5-tris(prop-2-yn-1-yloxy)benzoic acid via hydroxyl groups on its basal plane and finally treated with azide-glucoside. The obtained hydrophilic GNS were stable in water for 3 weeks. The results showed that both glucose-grafted GO sheets were reduced by sodium ascorbate during click-coupling reaction; this is one of the many advantages of click reaction. Finally, Fe3O4 nanoparticles were deposited on the sweet GNS and were superparamagnetic, responded quickly to an external magnetic field and exhibited efficient adsorption towards methylene blue, as a cationic dye. No leaching was observed even after a week of placing a magnet close to the vial containing the dispersion of magnetic sweet GNS.