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Biosensors with Amperometric Detection of Enzymatically Controlled pH‐Changes
Author(s) -
Bardea Amos,
Katz Eugenii,
Willner Itamar
Publication year - 2000
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200006)12:10<731::aid-elan731>3.0.co;2-6
Subject(s) - biosensor , chemistry , amperometry , ferrocene , pyrroloquinoline quinone , urease , redox , immobilized enzyme , electrode , combinatorial chemistry , inorganic chemistry , organic chemistry , urea , electrochemistry , biochemistry , enzyme , cofactor
New biosensors based on amperometric detection of enzymatically controlled pH‐changes are described. Pyrroloquinoline quinone (PQQ) is assembled as a monolayer onto a Au‐electrode, and α‐chymotrypsin or urease is covalently linked to the PQQ‐monolayer electrode. Biocatalyzed hydrolysis of N ‐acetyl‐4‐tyrosine ethyl ester ( 1 ) by α‐chymotrypsin or biocatalyzed degradation of urea ( 2 ) by urease alters the pH of the electrolyte solution. The changes in the pH are sensed by the redox‐potential of the PQQ‐redox‐active units associated with the electrode. Tethering of electroactive pH‐insensitive, ferrocene units to the protein enables the sensing of the pH variations by following the potential difference between PQQ and ferrocene electroactive units. This enables the use of the integrated PQQ‐ferrocene‐tethered enzyme electrode as a pH‐controlled biosensor with an internal potential reference.