title: Graphene Facilitated Removal of Labetalol in Laccase-ABTS System: Reaction Efficiency, Pathways and Mechanism.
abstract: The widespread occurrence of the beta-blocker labetalol causes environmental health concern. Enzymatic reactions are highly efficient and specific offering biochemical transformation of trace contaminants with short reaction time and little to none energy consumption. Our experiments indicate that labetalol can be effectively transformed by laccase-catalyzed reaction using 2, 2-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as a mediator, while no significant removal of labetalol can be achieved in the absence of ABTS. A total of three products were identified. It is interesting that the presence of graphene greatly increased the reaction rate while not changed the products. In the presence of 100 μg/L graphene, the pseudo-first-order reaction rate constant was increased ~50 times. We found that the enhancement of graphene is probably attributed to the formation and releasing of ABTS(2+) which has a much greater reactivity towards labetalol when graphene is present. This study provides fundamental information for laccase-ABTS mediated labetalol reactions and the effect of graphene, which could eventually lead to development of novel methods to control beta-blocker contamination.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China.
authors.forename: Shipeng
authors.initials: S
authors.lastname: Dong
authors.affiliation: National Laboratory of Solid State Microstructure and Department of Physics, Nanjing University, Nanjing 210093, P. R. China.
authors.forename: Huifang
authors.initials: H
authors.lastname: Xiao
authors.affiliation: Department of Crop and Soil Sciences, University of Georgia, Griffin, GA 30223, United States.
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Huang
authors.affiliation: National Laboratory of Solid State Microstructure and Department of Physics, Nanjing University, Nanjing 210093, P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Mao
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China.
authors.forename: Shixiang
authors.initials: S
authors.lastname: Gao
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry*; D001711:Biotransformation; D002384:Catalysis; D006108:Graphite / Q000737:chemistry*; D007741:Labetalol / Q000737:chemistry*; D042845:Laccase / Q000737:chemistry*; D053858:Metabolic Networks and Pathways; D013379:Substrate Specificity; D013451:Sulfonic Acids / Q000737:chemistry*; D013997:Time Factors
chemical_list: D052160:Benzothiazoles; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D006108:Graphite; D042845:Laccase; D007741:Labetalol