Colorimetric determination of xanthine in urine based on peroxidase-like activity of WO3 nanosheets

Two-dimensional WO 3 nanosheets were prepared by ultrasonic exfoliation of bulk WO 3 ·2H 2 O in water and characterized by transmission electron microscopy, atomic force microscopy , X-ray diffraction, X-ray photoelectron spectroscopy, Raman, dynamic light scattering . The nanosheets were discovered to possess the peroxidase-like catalytic activity, which can catalyze the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine by H 2 O 2 . The catalytic mechanism was also investigated by the scavenger experiments. Taking advantage of the peroxidase-like activity of WO 3 nanosheets, a facile colorimetric method for xanthine was developed by combining the oxidation reaction of xanthine catalyzed by xanthine oxidase. The linear range for xanthine was ranged from 25 to 200 μmol L −1 . The limit of detection for xanthine was 1.24 μmol L −1 . The colorimetric method was applied to determine xanthine in urine samples.