Synthesis of water soluble chitosan stabilized gold nanoparticles and determination of uric acid

Gold nanoparticles (Au-NPs) have been successfully synthesized by utilizing water soluble chitosan as reducing and stabilizing agent. The colloidal Au-NPs were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). The results showed that the colloidal Au-NPs had a plasmon absorption band with maximum wavelength in the range of 520-526 nm and the diameters were about 8-15 nm. In addition, a new Au-NPs-modified electrode was fabricated by self-assembling Au-NPs to the surface of the L-cysteine-modified glassy carbon electrode (Au-NPs L-Cys GCE). The Au-NPs-modified electrode showed an excellent character for electro-catalytic oxidization of uric acid (UA) in 0.1 mol L−1 phosphate buffer solution (pH 3.2). Using differential pulse anodic stripping voltammetry (DP-ASV), a high selectivity for determination of UA has been explored for the Au-NPs-modified electrode. DP-ASV peak currents of UA increased linearly with their concentration at the range of 2.0 × 10−6 to 4.0 × 10−5 mol L−1 with the detection limit of 2.7 × 10−6 mol L−1 for UA. The proposed method was applied for the detection of UA in human urine and serum samples with satisfactory results.