Architecture of Fe3O4–graphene oxide nanocomposite and its application as a platform for amino acid biosensing

The Fe 3 O 4 –graphene oxide (Fe 3 O 4 –GO) nanocomposites were prepared by a chemical co-precipitation of FeSO 4 , FeCl 3 ,·NH 3 ·H 2 O and GO. The Fe 3 O 4 –GO was characterized by scanning electron microscopy, X-ray powder diffraction, thermogravimetric analysis and electrochemical method. The results showed that ultrafine Fe 3 O 4 nanoparticles was prepared and densely assembled on GO nanosheets. The Fe 3 O 4 –GO exhibits large surface area and high catalysis towards the oxidation of cysteine and N-acetyl cysteine, which could be used for cysteine and N-acetyl cysteine sensing with a wide linear range (0.5–13.5   mM for cysteine and 0.12–13.3   mM for N-acetyl cysteine) and low detection limit (56   μM for cysteine and 25   μM for N-acetyl cysteine). The excellent catalytic activity, high sensitivity and good stability made such Fe 3 O 4 –GO nanocomposites to be promising nanomaterials for constructing nonenzymatic sensor.