In situ formation of Ag/Au nanorods as a platform to design a non-aggregation colorimetric assay for uric acid detection in biological fluids

Herein, we report on a sensitive probe for colorimetric detection of uric acid based on the formation of Ag shell on Au nanorods (Ag/AuNRs) in the presence of uric acid. Uric acid can reduce Ag+ to Ag atoms which deposit on the surface of AuNRs and form Ag shell. As a result of this phenomenon, the dielectric environment around AuNRs changes and the longitudinal surface plasmon resonance (SPR) peak of AuNRs blue-shifts, leading to the change of solution color from purple to green. Based on these facts, a colorimetric sensor for the detection of uric acid in the concentration range of 0.1-1.0 mu M with a detection limit of 0.065 mu M was developed. The method was applied for analysis of uric acid in human plasma and urine samples with satisfactory results. The sensor can be used for uric acid detection even with bare eyes.