Colorimetric and fluorescent detection of glucose based on Fe7S8 nanosheets catalyzed oxidation of o-phenylenediamine

Fe 7 S 8 nanosheets (Fe 7 S 8 NSs) was prepared from ferrous sulfate and thiourea, showing peroxidase-like activity and enabling the oxidation of o-phenylenediamine (OPD) in the presence of H 2 O 2 to produce 2,3-diaminophenol (DAP) with strong absorption and fluorescence peaks at 450 and 560 nm, respectively. Furthermore, both the level of absorbance at 450 nm ( A 450 ) and the intensity of fluorescence at 560 nm ( F 560 ) depended on the concentration of H 2 O 2 . As a result, a dual response (colorimetry and fluorescence) method for the assay of H 2 O 2 was established. Due to the fact that H 2 O 2 can be produced from glucose oxidase catalyzed glucose oxidation, A 450 and F 560 were further used for indirect   determination of glucose. The results indicated that the absorbance and fluorescence responses were closely related to glucose concentration in the range of 1.0–100 μM and 1.0––70 μM with the detection limit of 0.83 and 0.52 μM, respectively. To verify its practicality, the method has been used for determining glucose in human serum samples with recoveries ranging from 92.2 to 106.2 %, suggesting its promising potential applications.