A nanocomposite prepared from copper(II) and nitrogen-doped graphene quantum dots with peroxidase mimicking properties for chemiluminescent determination of uric acid.

Nitrogen-doped graphene quantum dots (N-GQD) were employed along with Cu(II) ions under alkaline conditions and room temperature to synthesize nanocomposites of type Cu(II)/Cu2O/N-GQDs. These nanocomposites exhibit excellent stability and dispersity, and also display a peroxidase-like activity that is superior to pure Cu2O nanoparticles and natural peroxidase (POx). A chemiluminescence (CL) method was designed that is based on the use of uricase which oxidizes uric acid under formation of H2O2. The nanocomposites were used as a POx mimic in the luminol-H2O2 CL system. Under optimized conditions, a linear relationship between CL intensity and the uric acid (UA) concentration in the range of 0.16-4.0 μM, and a detection limit of 0.041 μM (at S/N = 3) were obtained. The CL method was applied to the determination of UA in spiked serum and urine, and recoveries ranged from 85.0 to 121.3%. Graphical abstract Schematic presentation of synthesis strategy of Cu(II)/Cu2O/N-GQDs and the CL method based Cu(II)/Cu2O/N-GQDs for H2O2-meidated uric acid detection. The method can be used for the determination of uric acid (UA) with the detection limit of 0.041 μM.