Abstract: | Graphene oxide (GO) nanosheets can be functionalized with reactive pentafluorophenyl ester via esterification of the carboxylic groups. The resulting reactive GO nanosheets provide a versatile platform for grafting of amino‐containing polymers or biomolecules via ester–amine coupling. Coupling of poly(9,9‐dioctylfluorene)‐alt‐(4‐amino‐phenylcarbazole)] (PFCz‐NH2), amino‐terminated hyperbranched polyglycerol (HPG‐NH2), and lysozyme (Lyz) was illustrated. The Al/GO‐g‐PFCz/ITO sandwich thin‐film device exhibits bistable electrical switching and rewritable memory effects. The GO‐g‐Lyz nanohybrids exhibit high bactericidal efficacy against S. aureus and E. coli, while the GO‐g‐HPG nanohybrids exhibit reduced cytotoxicity toward 3T3 fibroblasts. |