title: Direct electrochemistry and bioelectrocatalysis of horseradish peroxidase based on gold nano-seeds dotted TiO2 nanocomposite.
abstract: Gold nano-seeds (GNSs) (capital EF, Cyrillic=2-5 nm) were dotted in TiO(2) colloids and the horseradish peroxidase (HRP) was successfully immobilized on the as-made GNSs-TiO(2) nanocomposite by a convenient and effective method. The matrix integrates the merits of both GNSs and TiO(2), which provides a favorable microenvironment for the immobilization of HRP. The cyclic votammetric results demonstrated that the entrapped HRP achieves direct electron transfer at glassy carbon electrode (GCE). A pair of stable and quasi-reversible redox peaks with a small peak-to-peak separation of 43 mV was observed in phosphate buffer solution. The GNSs stabilized by TiO(2) colloids acted sufficiently as the conducting tunnel to promote the electron transfer. As a result, the electrochemical behaviors were improved in virtue of the synergic effect of TiO(2) and GNSs. The Nafion/HRP-GNSs-TiO(2)/GCE displayed an excellent and rapid electrocatalytic response to the reduction of H(2)O(2). The proposed biosensor exhibited a good linear response in the range from 4.1 x 10(-5) to 6.3 x 10(-4) mol L(-1), with a detection limit of 5.9 x 10(-6) mol L(-1) (at the ration of signal to noise, S/N=3). The apparent Michaelis-Menten constant was estimated to be 0.63 mmol L(-1). Furthermore, the biosensor possesses satisfactory stability and good reproducibility.
authors.affiliation: Department of Chemistry, Shanghai Normal University, 100 Guilin Road, Xuhui District, Shanghai 200234, PR China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Wang
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Ma
authors.forename: Ying
authors.initials: Y
authors.lastname: Wen
authors.forename: Yueyi
authors.initials: Y
authors.lastname: Xing
authors.forename: Zongrang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Haifeng
authors.initials: H
authors.lastname: Yang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D002384:Catalysis; D003217:Conductometry / Q000295:instrumentation*; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000032:analysis* / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014025:Titanium / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; C009495:titanium dioxide; D006046:Gold; D006861:Hydrogen Peroxide; D014025:Titanium; D006735:Horseradish Peroxidase