Nitrosonaphthol reaction-assisted SERS assay for selective determination of 5-hydroxyindole-3-acetic acid in human urine.

Nitrosonaphthol reaction-assisted SERS assay for selective determination of 5-hydroxyindole-3-acetic acid in human urine. Anal Chim Acta. 2020 Oct 16;1134:34-40 Authors: Zhang Y, Li L, Gao Y, Wang X, Sun L, Ji W, Ozaki Y Abstract Urinary 5-hydroxyindole-3-acetic acid (5-HIAA) is a marker for diagnosis of patients with carcinoid tumors. In clinical practice, a simple colorimetric assay has widely been utilized for urinary 5-HIAA via its reaction with 1-nitroso-2-naphthol (NNa) in nitrous acid medium. However, this colorimetric assay has been criticized for lack of specificity. Herein, we proposed a novel SERS-based method for selective detection of urinary 5-HIAA by the use of a modified nitrosonaphthol reaction, in which hydrochloric acid is substituted for nitric acid to control the reaction conditions. This slight modification is crucial to be able to detect the cationic products in the acidic reaction mixture, because the chloride-aggregated Ag colloids not only create enormous hot spots for SERS enhancement, but also improve the chemical stability of nanostructured Ag substrates in acidic environment. Under optimized conditions, the present method can detect 5-HIAA within 12 min at concentrations as low as 1.2 ng/mL, which is 1000 times lower than that of conventional colorimetric method. And more importantly, the present method exhibits specific response toward 5-HIAA against other metabolites with similar structures in the ur...
Source: Analytica Chimica Acta - Category: Chemistry Authors: Tags: Anal Chim Acta Source Type: research