This work put forward a chemiluminescence method for rapid screening of nanoparticles-based mimetic enzymes, which is based on H 2 O 2 -luminol chemiluminesent reaction as a model system and six ferrite nanoparticles, namely, CoFe 2 O 4 、CuFe 2 O 4 、 γ -Fe 2 O 3 、MnFe 2 O 4 、precursor of NiFe 2 O 4 and precursor of magnesium ferrite as mimetic enzymes, and the results were compared with that of horseradish peroxidase (HRP). The results indicate: (1) Like HPR, the six ferrite magnetic nanoparticles are able to catalyze the oxidation of luminol by H 2 O 2 to produce enhanced chemiluminescence, and the catalytic activity of the studied six ferrite magnetic nanoparticles depends on the pH, temperature and substrate (H 2 O 2 ) concentration. Also, they could catalytically oxidize 3,3',5,5'-tetramethyl benzidine (TMB) by H 2 O 2 to produce a typical colour reaction. These results show that the ferrite magnetic nanoparticles possess intrinsic peroxidase properties. (2) The apparent Michaelis constants ( K m ) using H 2 O 2 as substrates were higher than that of HRP, in the order of CoFe 2 O 4 γ -Fe 2 O 3 2 O 4 2 O 4 2 O 4 < precursor of magnesium ferrite. (3) The ferrite magnetic nanoparticles show better pH and temperature tolerance than HRP. The proposed method promises the advantages of simplicity and rapidity, thus can be used for screening of the nanoparticles-based mimetic enzymes in large scale.
In this paper, the stable and good water-soluble polyacrylic acid functioned cerium oxide nanoparticles (CeO2 NPs) were successfully synthesized and characterized by dynamic light scattering (DLS), FT-IR and XPS. The experimental results indicated that the prepared CeO2 NPs exhibit intrinsic peroxidase-like activity, which can catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2 to produce blue reaction. Electron paramagnetic resonance (EPR) and Raman techniques were used to investigate the catalytic mechanism. On the basis of H2O2 concentration-dependent peroxidase-like activity of CeO2 NPs, a simple, low cost and selectively colorimetric method was constructed for sensing of glucose. Under the optimal conditions, the linear range for the determination of glucose was 0.5-10 mmol/L with a limit of detection (LOD, 3 σ ) of 0.1 mmol/L. The RSD was 2.4% for 1.0 mmol/L glucose ( n = 11). The proposed method has been successfully used for determination of glucose in serum samples.
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