title: Fabrication of herbicide biosensors based on the inhibition of enzyme activity that catalyzes the scavenging of hydrogen peroxide in a thylakoid membrane.
abstract: A novel herbicide biosensor with a thylakoid modified membrane electrode is presented. Thylakoid, isolated from spinach leaves, was entrapped in a membrane of poly (vinylalcohol) with the styrylpyridinium group (PVA-SbQ). The thylakoid membrane was fixed on the surface of a platinum electrode. It was found that the enzymes in thylakoid kept their activity for several months in the membrane. The oxidative current of hydrogen peroxide in a Tris-HCl buffer solution (pH 7.4) was detected at the modified electrode by a differential pulse voltammetric method. In the presence of herbicides, the oxidation current from the hydrogen peroxide decreased due to an inhibitor effect on the enzymes in thylakoid compared with that in the absence of the herbicides. The changes in the oxidation current at the electrode were proportional to the herbicide concentrations. The sensor could be used to detect herbicides in concentration ranges of 3 x 10(-9) - 1.5 x 10(-7) M for paraquat, 1 x 10(-8) - 3 x 10(-7) M for diuron, 4 x 10(-8) - 3 x 10(-6) M for prometryn, 5 x 10(-8) - 5 x 10(-6) M for atrazine and 1 x 10(-7) - 5 x 10(-6) M for ametryn, respectively. The enzyme activity on scavenging hydrogen peroxide in the modified PVA-SbQ membrane was examined.
authors.affiliation: Department of Material and Chemistry Engineering, Guilin University of Technology, Guilin 541004, China. likianping@263.net
authors.forename: Jianping
authors.initials: J
authors.lastname: Li
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wei
authors.forename: Tuzhi
authors.initials: T
authors.lastname: Peng
mesh_terms: D015374:Biosensing Techniques; D002384:Catalysis; D004563:Electrochemistry; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000737:chemistry*; D006540:Herbicides / Q000032:analysis* / Q000378:metabolism / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008567:Membranes, Artificial; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism; D012680:Sensitivity and Specificity; D020524:Thylakoids / Q000737:chemistry / Q000201:enzymology*
chemical_list: D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D006540:Herbicides; D008567:Membranes, Artificial; D009097:Multienzyme Complexes; D006861:Hydrogen Peroxide