Colorimetric Detection of Uric Acid with High Sensitivity Using Cu2O@Ag Nanocomposites

In this paper, we built the Cu 2 O@Ag nanocomposites-catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB)–H 2 O 2 system for sensitive, rapid, and low-cost colorimetric sensing of uric acid (UA). Firstly, Ag nanotriangles were synthesized by dynamic method, and then Cu 2 O was encapsulated on the nanoflakes to synthesize Cu 2 O@Ag nanocomposites. Characterization of the structure and morphology of nanocomposites material were characterized by transmission electron microscopy, X-ray energy-dispersive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Cu 2 O@Ag nanocomposites could catalyze the oxidation of TMB by H 2 O 2 (which is produced by enzymatic oxidation of UA), and the color changes from colorless to blue can be observed directly with the naked eyes or can be detected by UV–Vis spectrophotometer. The colorimetric sensor provided a linear absorbance response in the 0.5–100 μM UA concentration range with a 0.4 μM detection limit (S/N = 3). The recovery of UA in human serum by the proposed sensor is over 95.7%. Thus, these results imply that the UA sensor provides an effective tool in fast clinical analysis of gout without the need for expensive and advanced equipment.