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Thu Duc District, Vietnam

Le T.L.,Quang Nam Junior of economics Technology | Dinh Q.K.,Hue University | Tran T.H.,Hue University | Nguyen H.P.,Hue University | And 2 more authors.
Advances in Natural Sciences: Nanoscience and Nanotechnology

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. © 2014 Vietnam Academy of Science & Technology. Source

Duy N.N.,Viet Nam Atomic Energy Institute | Du D.X.,Hue University | Van Phu D.,Viet Nam Atomic Energy Institute | Quoc L.A.,Viet Nam Atomic Energy Institute | And 2 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects

Gold nanoparticles (AuNPs) with size in the range of 10-50nm were synthesized by γCo-60 irradiation using water soluble chitosan (WSC) as stabilizer and size enlargement by seed approach. The maximum absorption wavelength (λmax) was measured by UV-vis spectroscopy and particle size was determined from TEM images. Results showed that value of λmax increased from 523nm (seed particles) to 525, 537 and 549nm and the size of AuNPs increased from 10nm (seed particles) to 20, 38 and 53nm for concentration ratio of [Au3+]/[Au0] (seed) of 2.5, 5 and 10, respectively. When [Au3+]/[Au0]=20 and 40, the size of AuNPs was not further increased. Antioxidant activity of AuNPs with size of 10, 20, 38 and 53nm was investigated using free radical 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+). Results indicated that among the size of AuNPs tested, AuNPs of 10nm exhibited the strongest antioxidant activity. Thus, due to the compatibility of WSC and unique property of AuNPs, AuNPs/WSC synthesized by γ-irradiation method can be potentially applied in biomedicines, cosmetics and in other fields as well. © 2013 Elsevier B.V. Source

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