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Electron‐Transfer Mediator Microbiosensor Fabrication Based on Immobilizing HRP‐Labeled Au Colloids on Gold Electrode Surface by 11‐Mercaptoundecanoic Acid Monolayer
Author(s) -
Tang Dianping,
Yuan Ruo,
Chai Yaqin
Publication year - 2006
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200503397
Subject(s) - monolayer , amperometry , thionine , colloid , horseradish peroxidase , substrate (aquarium) , biosensor , chemistry , colloidal gold , electrode , covalent bond , chemical engineering , electrochemistry , nanoparticle , nanotechnology , materials science , organic chemistry , enzyme , biochemistry , oceanography , engineering , geology
Abstract In this paper, a new strategy for constructing a mediator‐type amperometric hydrogen peroxide (H 2 O 2 ) microbiosensor was described. An electropolymerized thionine film (PTH) was deposited directly onto a gold electrode surface. The resulting redox film was extremely thin, adhered well onto a substrate (electrode), and had a highly cross‐linked network structure. Consequently, horseradish peroxidase (HRP) was successfully immobilized on nanometer‐sized Au colloids, which were supported by thiol‐tailed groups of 11‐mercaptoundecanoic acid (11‐MUA) monolayer covalently bound onto PTH film. With the aid of the PTH mediator, HRP‐labeled Au colloids microbiosensor displayed excellent electrocatalytical response to the reduction of H 2 O 2 . This matrix showed a biocompatible microenvironment for retaining the native activity of the covalent HRP and a very low mass transport barrier to the substrate, which provided a fast amperometric response to H 2 O 2 . The proposed H 2 O 2 microbiosensor exhibited linear range of 3.5 μM–0.7 mM with a detection limit of 0.05 μM (S/N=3). The response showed a Michaelis‐Menten behavior at larger H 2 O 2 concentrations. The K M app value for the biosensors based on 24 nm Au colloids was found to be 47 μM, which demonstrated that HRP immobilized on Au colloids exhibited a high affinity to H 2 O 2 with no loss of enzymatic activity. This microbiosensor possessed good analytical performance and storage stability.