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Oxygen Dependence in a Dual‐Phase Electrochemical Biosensing System
Author(s) -
Zhang Shanqing,
Zhao Huijun,
John Richard
Publication year - 2005
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.200303088
Subject(s) - tyrosinase , chemistry , substrate (aquarium) , biosensor , aqueous solution , oxygen , electrochemistry , phenol , aqueous two phase system , limiting oxygen concentration , inorganic chemistry , photochemistry , nuclear chemistry , organic chemistry , electrode , enzyme , biochemistry , oceanography , geology
Oxygen dependence of a tyrosinase‐based electrochemical biosensor for determination of phenol in aqueous and organic media was systematically investigated. The result demonstrated that the enzymatic coupling reaction rate of tyrosinase ( deoxy form) and O 2 to regenerate tyrosinase ( oxy form) is a kinetically fast reaction, and the significant change of O 2 concentration in aqueous solution did not affect the coupling reaction. The further increase of O 2 concentration did not increase the overall oxidation reaction rate of the substrate at low substrate concentration (e.g.,<10 μM phenol) when O 2 concentration was greater than 8.9 ppm. The oxygen dependence was observed in the case of high substrate concentration due to insufficient amount of O 2 available for the regeneration of tyrosinase. In other words, the upper linear range is oxygen dependent for tyrosinase biosensors. The phenol biosensors employing microelectrodes had wider upper linear ranges than macroelectrodes in both aqueous and organic phase, which can be explained by the oxygen dependence.