Xanthine oxidase/laponite nanoparticles immobilized on glassy carbon electrode: direct electron transfer and multielectrocatalysis.
In this work, colloidal laponite nanoparticles were further expanded into the design of the third-generation biosensor. Direct electrochemistry of the complex molybdoenzyme xanthine oxidase (XnOx) immobilized on glassy carbon electrode (GCE) by laponite nanoparticles was investigated for the first time. XnOx/laponite thin film modified electrode showed only one pair of well defined and reversible cyclic voltammetric peaks attributed to XnOx-FAD cofactor at about -0.370 V vs. SCE (pH 5). The formal potential of XnOx-FAD/FADH(2) couple varied linearly with the increase of pH in the range of 4.0-8.0 with a slope of -54.3 mV pH(-1), which indicated that two-proton transfer was accompanied with two-electron transfer in the electrochemical reaction. More interestingly, the immobilized XnOx retained its biological activity well and displayed an excellent electrocatalytic performance to both the oxidation of xanthine and the reduction of nitrate. The electrocatalytic response showed a linear dependence on the xanthine concentration ranging from 3.9 x 10(-8) to 2.1 x 10(-5)M with a detection limit of 1.0 x 10(-8)M based on S/N=3.
Shan
Dan
D
College of Chemistry & Chemical Engineering, Yangzhou University, Jiangsu 225002, China. danshan@yzu.edu.cn
Wang
Yan-Na
YN
Xue
Huai-Guo
HG
Cosnier
Serge
S
Ding
Shou-Nian
SN
D000327:Adsorption; D015374:Biosensing Techniques / Q000295:instrumentation*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D004563:Electrochemistry / Q000295:instrumentation*; D004579:Electron Transport; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005898:Glass / Q000737:chemistry; D008839:Microelectrodes; D053758:Nanoparticles / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D019820:Xanthine / Q000032:analysis* / Q000737:chemistry; D014969:Xanthine Oxidase / Q000737:chemistry*
D017640:Silicates; D019820:Xanthine; D002244:Carbon; C524813:laponite; D014969:Xanthine Oxidase