Optical Biosensors Based on Nitrogen‐Doped Graphene Functionalized with Magnetic Nanoparticles

Nanocomposites from nitrogen‐doped graphene (NG) and magnetic nanoparticles (MNPs) are prepared via an edge‐functionalized ball milling approach, followed by a coprecipitation method. Catalytic peroxidase‐like activity of the resulting MNP/NG is investigated. The as‐synthesized MNP/NG nanocomposites are used to catalyze the colorimetric reaction between hydrogen peroxide (H 2 O 2 ) and 2,2′‐azino‐bis(3‐ethylbenzo‐thiazoline‐6‐sulfonic acid) diammonium salt (ABTS). Typical absorption peaks associated with the oxidation of ABTS are found to increase linearly with increasing H 2 O 2 concentrations up to 10.0 × 10 −3 m with a detection limit of 17.1 × 10 −6 m . Rapid detection of H 2 O 2 with the use of MNP/NG is confirmed further by a glucose biosensor. Concentrations of glucose could be monitored by detection of H 2 O 2 since H 2 O 2 is generated during oxidation of glucose by glucose oxidase (GOx). The absorption intensity increases significantly with increasing glucose amounts up to 18.0 × 10 −3 m glucose, with a detection limit of 59.7 × 10 −6 m , indicating a high performance for glucose detection.