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Published on: March 12, 2015
Extended-gate FET-based enzyme sensor with ferrocenyl-alkanethiol modified gold sensing electrode
Yu Ishige1, Maki Shimoda, Masao Kamahori
1Central Research Laboratory, Hitachi Ltd., 1-280 Higashi-Koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan.
Biosensors & Bioelectronics
|August 2, 2008
Summary
A novel field-effect transistor (FET)-based enzyme sensor utilizes an 11-ferrocenyl-1-undecanethiol (11-FUT) modified electrode to detect redox reactions. This sensor is unaffected by buffer conditions, offering a sensitive and pH-independent method for enzyme assays, including cholesterol detection.
Area of Science:
- * Biosensors and electrochemical devices
- * Nanomaterials and surface modification
- * Enzyme-based diagnostics
Background:
- * Existing ion-sensitive field-effect transistor (ISFET) enzyme sensors are highly sensitive to buffer conditions (pH, capacity).
- * This limits their reliability and applicability in complex biological samples.
- * A new approach is needed for robust, buffer-independent enzyme detection.
Purpose of the Study:
- * To develop a novel field-effect transistor (FET)-based enzyme sensor.
- * To demonstrate its independence from buffer conditions by detecting redox reactions.
- * To apply the sensor for sensitive and accurate cholesterol level measurement.
Main Methods:
- * Fabricated an extended-gate FET sensor with a gold electrode modified by 11-ferrocenyl-1-undecanethiol (11-FUT).
- * Utilized the interfacial potential change caused by enzyme-catalyzed redox reactions for detection.
- * Incorporated cholesterol dehydrogenase and hexacyanoferrate ions for cholesterol sensing.
Main Results:
- * The FET sensor exhibited Nernstian response (59 mV/decade) to hexacyanoferrate redox reactions, independent of pH.
- * Demonstrated a wide dynamic range (>5 orders) and high sensitivity.
- * Successfully measured serum cholesterol levels (33-233 mg/dL) with a Nernstian slope of 57 mV/decade using only 2.5 microL sample volume.
Conclusions:
- * The developed FET-based enzyme sensor offers a robust alternative to ISFET sensors, unaffected by buffer variations.
- * The sensor shows high sensitivity, a broad dynamic range, and pH independence.
- * This technology holds promise for miniaturized, reliable point-of-care diagnostic devices, particularly for cholesterol monitoring.
