Pd nanoparticles supported on nitrogen, sulfur-doped three-dimensional hierarchical nanostructures as peroxidase-like catalysts for colorimetric detection of xanthine

Pd nanoparticles supported on nitrogen, sulfur-doped three-dimensional hierarchical nanostructures (Pd/N-S-CS) were successfully prepared by glycol reduction of Pd on nitrogen, sulfur-doped three-dimensional hierarchical nanostructures (N-S-CS) using humic acid (HA) and thiourea as the precursors. Transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and Xray photoelectron spectroscopy (XPS) were employed to confirm the characterization of Pd/N-S-CS. The results showed that the obtained Pd/N-S-CS had interesting three-dimensional hierarchical nanostructures which were composed of nanosheets, and Pd nanoparticles with an average diameter of 6 nm were distributed on the surface of the nanosheets. Furthermore, the Pd/N-S-CS exhibited excellent peroxidase-like activity and it can effectively catalyze the classical peroxidase substrate 3,30,5,50-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. Based on this finding, a simple, sensitive, and selective colorimetric method for H2O2 and xanthine detection was developed and applied to detect xanthine in urine samples. The detection limit of H2O2 and xanthine were 3.3 x 10(-6) M and 2.9 x 10(-7) M, respectively. This work is expected to provide a novel and efficient method for the detection of xanthine in the human body.