Graphene quantum dots nanosensor derived from 3D nanomesh graphene frameworks and its application for fluorescent sensing of Cu2+ in rat brain

Abstract

Abstract Herein, we report a facile yet effective fluorescent nanosensor for the direct, selective and sensitive determination of cerebral Cu2+ in the rat brain microdialysate. The fluorescent nanosensor is constructed by utilizing the strong fluorescent graphene quantum dots (GQDs) as the fluorescent signaling output, which were synthesized via chemical oxidation from 3D nanomesh graphene frameworks (NGFs). Initially, the as-prepared GQDs displays a uniform size with lateral size below 5 nm is observed to exhibit photoluminescence properties. The subsequent addition of Cu2+ into the GQDs mixture results in the significant quenching of the fluorescence of GQDs. The quenching degree of Cu2+ towards GQDs is highly sensitive to the concentration of Cu2+ and shows a linear relationship for Cu2+ within the range from 0.1 μM to 1.0 μM with a limit of detection (LOD) of 0.067 μM which substantially enables the GQDs as a nanosensor for Cu2+. Moreover, the as-fabricated nanosenor displays a high specificity for Cu2+ irrespective of the coexistence of other metal ions, amino acids, and biological substance that endogenously existed in the rat brain and has been employed to successfully determination of Cu2+ in rat brain with the basal value of 2.21 ± 0.76 μM (n = 3).