One-pot synthesis of CeO2-carbon dots with enhanced peroxidase-like activity and carbon dots for ratiometric fluorescence detection of H2O2 and cholesterol

Abstract Carbon dots-doped CeO2 (CeO2-CDs) with enhanced peroxidase-like activity and fluorescent carbon dots (CDs) were prepared by one-pot hydrothermal method in this work. The morphology, surface groups and enzymatic properties of CeO2-CDs and optical properties of CDs were studied in detail. The enzyme activity of CeO2-CDs was higher than CeO2 due to the smaller particle size. O-phenylenediamine (OPD) as peroxidase substrate can be catalyzed to fluorescent o-phenylenediamine (oxOPD) by CeO2-CDs, and the UV–vis absorption of oxOPD overlapped partly with the fluorescence emission of CDs. Hence, the fluorescence intensity of CDs would be decreased by oxOPD due to the inner filter effect. Based on this, a sensitive and selective ratiometric fluorescence method for H2O2 and cholesterol was developed. The detection ranges for H2O2 and cholesterol are 1.67 µM-2.01 mM and 1.66 µM-1.65 mM with the detection limits are 0.35 µM and 0.49 µM (3Ϭ), respectively. Moreover, this method has been successfully used to detect cholesterol in human serum.