The Enhanced Photo-Electrochemical Detection of Uric Acid on Au Nanoparticles Modified Glassy Carbon Electrode

Abstract

In this work, a sensitive and novel method for determining uric acid (UA) has been developed, in which the glassy carbon electrode (GCE) was modified with electrodeposition Au nanoparticles and used to monitor the concentration of UA with the assistant of visible light illumination. The morphology of the Au nanoparticles deposited on GCE surface were characterized by scanning electron microscope (SEM) and the nanoparticles were found to be well-dispersed spheres with the average diameter approaching 26.1 nm. A series of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements have revealed that the introduction of visible light can greatly enhance both the strength and stability of response current due to the surface plasmon resonance (SPR). Specifically, the DPV showed a linear relationship between peak current and UA concentration in the range of 2.8 to 57.5 μM with the equation of I _pa (μA) = 0.0121c _UA (μM) + 0.3122 (R ² = 0.9987). Herein, the visible light illuminated Au/GCE possesses a potential to be a sensitive electrochemical sensor in the future.

Keywords: AuNPs; Uric acid; Visible light.

Fig. 1

SEM images of Au/GCE at lower (a) and higher magnification (b). Inset: corresponding Au nanoparticles size distribution histogram

Fig. 2

CVs of Au/GCE in 0.1 M PBS (pH 7.0) solution containing 1.0 mM UA with (a) and without (b) visible light illumination. Scan rate 50 mV s⁻¹

Fig. 3

a Potential/V vs.SCE. The CV of Au/GCE in 0.1 M PBS (pH 7.0) solution containing 1.0 mM UA without (1) and with (3) visible light illumination; visible light illumination starts from the spot where the arrow is pointing (2). Scan rate 50 mV s⁻¹. b Time/s. Photocurrent response of Au/GCE under visible light illumination in 0.1 M PBS (pH 7.0) solution containing 1.0 mM UA at 0.48 V. The illumination from a Xe lamp was interrupted every 30 s

Fig. 4

CVs of Au/GCE electrodeposited with different quantity of gold: 57.8 (a), 28.9 (b), 9.6 (c), 4.8 (d), 0.96 μg/cm² (e), and bare GCE (f) in 0.1 M PBS (pH 7.0) solution containing 1.0 mM UA under visible light illumination. Scan rate 50 mV s⁻¹. Depositing potential −0.2 V

Fig. 5

a CVs of the Au/GCE in 1 mM UA with different pH PBS solution (pH = 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0), scan rate 50 mV s⁻¹. b Relationship between the oxidation peak current and pH value

Fig. 6

CVs of the Au/GCE in 0.1 M PBS (pH = 7.0) solution containing 1 mM UA at scan rates ranging from 20 to 200 mV s⁻¹. Inset: calibration curve of peak current vs. v^1/2

Fig. 7

a DPV curves of the Au/GCE in 0.1 M PBS (pH 7.0) at different concentrations of UA. b Plots of anodic peak currents vs. concentration of UA