Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10276306 | Journal of Electroanalytical Chemistry | 2005 | 8 Pages |
Abstract
Enzyme entrapped in an electrosynthesized polymer film on a high-surface-area electrode is shown to be an attractive platform for the important class of amperometric biosensors based on oxidases and electrooxidation of the H2O2 generated by enzyme-catalyzed oxidation of analyte. Two Pt electrode surface morphologies, Pt black (Pt-BLK) and Pt nanowire brush (Pt-NW) were electrodeposited from chloroplatinic acid. Glucose oxidase (GOx) served as the model enzyme, which was entrapped in an electropolymerized polypyrrole (PPY) film on the high-surface-area Pt electrodes. The glucose sensitivity of the GOx electrodes can be controlled simply through Pt deposition conditions and varies roughly linearly with electrode microscopic roughness factor. A sensitivity of 103 μA mMâ1 cmâ2 was achieved with the Pt-BLK/PPY-immobilized GOx system at an underlying electrode surface roughness of 318, which is 150-fold higher than the sensitivity of a bare evaporated Pt/PPY-immobilized GOx electrode with a surface roughness of â¼2-3. The apparent Michaelis constant for PPY-immobilized GOx (â¼30 mM) is similar to that for free enzyme (25 mM) suggesting that the overall electrode kinetics are not limited by glucose mass transfer. Scanning electron micrographs of enzyme electrode surfaces and a fluorescence assay to determine immobilized GOx concentration revealed that the PPY-GOx layer is deposited as a thin film that follows the contours of the electrode surface and that up to 3-fold greater enzyme is entrapped on the roughest electrodes examined. The orders of magnitude greater sensitivity of enzyme electrodes based on high-surface-area Pt appears likely to be due to increased H2O2 electrooxidation efficiency.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Engineering (General)
Authors
Jianjun Wang, Nosang V. Myung, Minhee Yun, Harold G. Monbouquette,