Enzyme-free uric acid electrochemical sensors using β-cyclodextrin-modified carboxylic acid-functionalized carbon nanotubes

Carboxylic acid-functionalized multi-walled carbon nanotubes (COOH-MWCNT) were modified via ultrasonication with β-cyclodextrin (β-CD) to obtain a COOH-MWCNT:β-CD nanocomposite material for the purpose of developing an enzyme-free electrochemical sensor for uric acid—a clinically relevant molecule implemented in pregnancy-induced hypertension diagnosis. The nanocomposite material is deposited onto glassy carbon electrodes and subsequently capped with layers of Nafion and Hydrothane polyurethane. The surface morphology and electronic structure of the nanocomposite material were characterized using UV–Vis, TEM, and FTIR. The performance of the electrochemical sensor was measured through direct injection of UA during amperometry. With the high surface area of the COOH-MWCNT in concert with the selectivity provided by β-CD, the composite system outperforms similar COOH-MWCNT systems, displaying enhanced UA sensitivity versus films with only COOH-MWCNT. With the improved sensitivity (4.28 ± 0.11 µA mM −1 ) and fast response time (4.0 ± 0.5 s), the sensors offer wide detection of UA across clinically relevant ranges (100–700 μM) as well as demonstrated selectivity against various interferents.