Colorimetric determination of uric acid based on the suppression of oxidative etching of silver nanoparticles by chloroauric acid.

A colorimetric method is described for the determination of uric acid (UA). The assay is based on oxidative etching of silver nanoparticles (AgNPs) by chloroauric acid (HAuCl4). The presence of UA suppresses the redox reaction between AgNPs and HAuCl4 because a competitive reaction occurs between HAuCl4 and UA. This results in a color change of the solution from brown to yellow. In parallel, the absorbance is blue shifted from 477 to 428 nm. The method has a detection limit as low as 30 pM (at S/N = 3) and a linear response range that covers the 0.1 nM to 0.1 mM UA concentration range. The reliability of the method was successfully demonstrated by analyzing spiked serum samples. Graphical abstractSchematic representation of a colorimetric method for determination of uric acid (UA) based on oxidative etching of silver nanoparticles by HAuCl4.