title: Mixed monolayers of ferrocenylalkanethiol and encapsulated horseradish peroxidase for sensitive and durable electrochemical detection of hydrogen peroxide.
abstract: This paper describes the construction of a mixed monolayer of ferrocenylalkanethiol and encapsulated horseradish peroxidase (HRP) at a gold electrode for amperometric detection of H(2)O(2) at trace levels. By tuning the alkanethiol chain lengths that tether the HRP enzyme and the ferrocenylalkanethiol (FcC(11)SH) mediator, facile electron transfer between FcC(11)SH and HRP can be achieved. Unlike most HRP-based electrochemical sensors, which rely on HRP-facilitated H(2)O(2) reduction (to H(2)O), the electrocatalytic current is resulted from an HRP-catalyzed oxidation reaction of H(2)O(2) (to O(2)). Upon optimizing other experimental conditions (surface coverage ratio, pH, and flow rate), the electrocatalytic reaction proceeding at the electrode was used to attain a low amperometric detection level (0.64 nM) and a dynamic range spanning over 3 orders of magnitude. Not only does the thin hydrophilic porous HRP capsule allow facile electron transfer, it also enables H(2)O(2) to permeate. More significantly, the enzymatic activity of the encapsulated HRP is retained for a considerably longer period (>3 weeks) than naked HRP molecules attached to an electrode or those wired to a redox polymer thin film. By comparing to electrodes modified with denatured HRP that are subsequently encapsulated or embedded in a poly-L-lysine matrix, it is concluded that the encapsulation has significantly preserved the native structure of HRP and therefore its enzymatic activity. The electrode covered with FcC(11)SH and encapsulated HRP is shown to be capable of rapidly and reproducibly detecting H(2)O(2) present in complex sample media.
authors.affiliation: Department of Chemistry and Biochemistry, California State University, Los Angeles, Los Angeles, California 90032, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Peng
authors.forename: Dianlu
authors.initials: D
authors.lastname: Jiang
authors.forename: Lei
authors.initials: L
authors.lastname: Su
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Ming
authors.initials: M
authors.lastname: Yan
authors.forename: Juanjuan
authors.initials: J
authors.lastname: Du
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Lu
authors.forename: You-Nian
authors.initials: YN
authors.lastname: Liu
authors.forename: Feimeng
authors.initials: F
authors.lastname: Zhou
mesh_terms: D055162:Biocatalysis; D004563:Electrochemistry; D004566:Electrodes; D005296:Ferrous Compounds / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000032:analysis*; D008567:Membranes, Artificial; D010084:Oxidation-Reduction
chemical_list: D005296:Ferrous Compounds; D008567:Membranes, Artificial; D006046:Gold; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase