The Influence of Gold Nanoparticles on Simultaneous Determination of Uric Acid and Ascorbic Acid

Abstract

A three-dimensional L-cysteine (L-cys) monolayer assembled on gold nanoparticles (GNP) providing simultaneous detection of uric acid (UA) and ascorbic acid (AA) was studied in this work. The cyclic voltammetry demonstrated that, at a bare glassy carbon electrode (GCE) or planar gold electrode, the mixture of UA and AA showed one overlapped oxidation peak; whereas when the electrode was modified with GNP, the oxidation peaks for UA and AA were separated. While a GNP modified electrode was further modified with L-cys monolayer (L-cys/GNP/GCE), namely, three-dimensional L-cys monolayer, a better separation for UA and AA response was obtained. Interestingly, the L-cys monolayer-modified planar gold electrode presented a block effect on the oxidation of AA, which was facilitated by the three-dimensional L-cys monolayer attributed to its distinct structure. The pH of solution presented a noticeable effect on the separation of UA and AA at GNP modified electrodes with or without L-cys monolayer. Wide concentration ranges from 2 × 10⁻⁶−1 × 10⁻³ M to UA and 2 × 10⁻⁶−8 × 10⁻⁴ M to AA could be obtained at L-cys/GNP/GCE.

Keywords:

• Ascorbic acid
• Gold nanoparticle
• L-Cysteine
• Three-dimensional monolayer
• Uric acid simultaneous determination

Acknowledgments

This work was supported by the Research Foundation for Outstanding Young Teachers, China University of Geosciences (Wuhan) (No. CUGQNL0902).

Notes

E_UA and E_AA mean the oxidation potentials of UA and AA at the modified electrode.

i_UA and i_AA mean the oxidation currents of UA and AA at the modified electrode.

ΔE = E_UA−E_AA.