Colorimetric and Fluorescent Detection of Glucose Based on Fe7S8 Nanosheets Catalyzed Oxidation of O-Phenylenediamine

Fe7S8 nanosheets (Fe7S8 NSs) was prepared from ferrous sulfate and thiourea, showing peroxidase-like activity and enabling the oxidation of o-phenylenediamine (OPD) in the presence of H2O2 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 (A450) and the intensity of fluorescence at 560 nm (F560) depended on the concentration of H2O2. As a result, a dual response (colorimetry and fluorescence) method for the assay of H2O2 was established. Due to the fact that H2O2 can be produced from glucose oxidase catalyzed glucose oxidation, A450 and F560 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 mu M and 1.0--70 mu M with the detection limit of 0.83 and 0.52 mu M, 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.