Stimuli-Responsive Graphene Nanohybrids for Biomedical Applications

Figure 2

Schematic showing various covalent functionalization chemistries of graphene or GO. I: reduction of GO into graphene by various approaches ((1) NaBH₄, (2) KOH/H₂O, and (3) N₂H₄). II: covalent surface functionalization of reduced graphene via diazonium reaction (ArN2X). III: functionalization of GO by the reaction between GO and sodium azide. IV: reduction of azide functionalized GO (azide–GO) with LiAlH₄ resulting in the amino-functionalized GO. V: functionalization of azide–GO through click chemistry (R–ChCH/CuSO₄). VI: modification of GO with long alkyl chains ((1) SOCl₂ and (2) RNH₂) by the acylation reaction between the carboxyl acid groups of GO and alkylamine (after SOCl₂ activation of the COOH groups). VII: esterification of GO by DCC chemistry or the acylation reaction between the carboxyl acid groups of GO and ROH alkylamine (after SOCl₂ activation of the COOH groups) ((1) DCC/DMAP or SOCl₂ and (2) ROH). VIII: nucleophilic ring-opening reaction between the epoxy groups of GO and the amine groups of an amine-terminated organic molecular (RNH₂). IX: the treatment of GO with organic isocyanates leading to the derivatization of both the edge carboxyl and surface hydroxyl functional groups via formation of amides or carbamate esters (RNCO) [44].