Non-enzymatic glucose electrochemical sensor based on nitrogen-doped graphene modified with polyaniline and Fe3O4@MIL-101-NH2 nano framework

In this study, a novel highly sensitive and selective non-enzymatic glucose sensor was fabricated by coating simple and cheap graphite sheet (GS) electrodes with a proper conductive nanocomposite containing nitrogen-doped functionalized graphene (NFG), conductive polyaniline (PANI), and core-shell nanoparticles (Fe3O4@-MIL-101-NH2). The results revealed that the core centers of iron oxide nanoparticles shelled by MIL-101-NH2 enhanced the electron transfer and led to more conductivity, also their existence caused the limitation of the MOF's low conductivity. In addition, using Fe3O4@MIL-101-NH2 in the nanocomposite structure led to more sensitivity and selectivity at glucose monitoring due to its amine groups and unique structure. The results showed that NFG/PANI/Fe3O4@MIL-101-NH2 nanocomposite provided a large surface area besides enhanced electron transfer and catalytic properties that lead to proper oxidation of glucose with two linear ranges of 0.5 - 10 mu M and 100 mu M - 25 mM and a low detection limit of 0.3 mu M (S/N = 3). Furthermore, the relative standard deviation (RSD%) in all detection processes was lower than 9 %. Finally, the performance of fabricated non-enzymatic sensor (GS/NFG/PANI/Fe3O4@MIL-101-NH2) in human fluids real samples including serum and plasma was acceptable which significantly indicates that it is toward monitoring of glucose in clinical applications.