Plasmon-based detection of Uric Acid in aqueous solution using colloidal Ag nanoparticles

Citrate coated stable colloidal silver nanoparticles (Ag NPs) with diameter ranging from 5 to 30 nm was synthesized by UV-induced citrate reduction of aqueous AgNO3 solution. The as-prepared colloid appeared as reddish yellow in colour. The UV-VIS absorption spectrum of the as-prepared colloid exhibited an intense and single plasmonic peak centered at ~ 405 nm implying densely formation of spherical NPs. The colloidal Ag NPs were very stable showing no prominent ageing even after few weeks. The linear red shift of plasmonic peak of Ag NPs was observed in UV–Visible spectroscopy with increase of uric acid concentration in Ag NP-based colloid in the range from 5 nM to 10 mM. This colloidal solution showed excellent sensitivity for uric acid identification and was employed for the quantitative detection of uric acid down to 5 nM limit.