A novel fluorimetric sensing strategy for highly sensitive detection of phytic acid and hydrogen peroxide.

In this paper, we developed a sensitive sensor for phytic acid (PA) and hydrogen peroxide (H2O2) detection based on glutathione-functionalized graphene quantum dots (GQDs@GSH). The fluorescence of GQDs@GSH was found to be effectively quenched by Fe3+ ions via photo-induced electron transfer (PET) process. Upon the addition of PA to GQDs@GSH/Fe3+ system, the fluorescence of GQDs@GSH was significantly restored due to the strong chelating and reducing ability of PA, Fe3+ ions could be reduced to Fe2+ ions by PA and formed PA/Fe2+ complex. Therefore, the "off-on" fluorescence method was constructed to detect PA by using GQDs@GSH/Fe3+ as a fluorescent probe. Furthermore, the method can be used for the detection of H2O2. H2O2 can destroy the chelate structure of PA/Fe2+, release Fe2+ ions and oxidize Fe2+ ions to produce Fe3+ ions, leading to the fluorescence quenching of GQDs@GSH again. Under optimal conditions, the fluorescence sensing platform showed good linear relationship between the relative fluorescence intensity I/I0 and the concentration of PA and H2O2 in the range of 0.05-3 μmol L-1 and 0.5-10 μmol L-1, respectively. The detection limits of PA and H2O2 were 14 nmol L-1 and 0.134 μmol L-1, respectively. Furthermore, the fluorescence assay method was also applied in real sample analysis and satisfactory results were obtained.