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Insulin oxidation and determination at carbon electrodes
Maogen Zhang1, Conor Mullens, Waldemar Gorski
1Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249-0698, USA.
Analytical Chemistry
|October 1, 2005
Summary
New glassy carbon electrodes coated with chitosan and multiwalled carbon nanotubes enable stable insulin detection. These advanced biosensors show promise for diabetes research and therapeutic insulin analysis.
Area of Science:
- Electrochemistry
- Biomaterials Science
- Analytical Chemistry
Background:
- Insulin oxidation at bare electrodes leads to rapid deactivation.
- Development of stable and sensitive electrochemical sensors for insulin is crucial for diabetes management.
Purpose of the Study:
- To investigate the redox chemistry of insulin using modified electrodes.
- To develop a stable amperometric sensor for insulin determination.
Main Methods:
- Coating glassy carbon (GC) electrodes with chitosan (CHIT) and multiwalled carbon nanotubes (CNT).
- Electrochemical characterization of insulin oxidation using GC/CHIT-CNT electrodes.
- Mass spectrometry, electron paramagnetic resonance, and separation studies to elucidate oxidation products.
Main Results:
- GC/CHIT-CNT electrodes exhibited stable insulin currents, unlike bare electrodes.
- Insulin oxidation involved the formation of two intramolecular dityrosine cross-links.
- The sensor achieved a detection limit of ~30 nM, sensitivity of 135 mA M⁻¹ cm⁻², and a linear dynamic range of 0.10–3.0 µM at pH 7.40.
Conclusions:
- GC/CHIT-CNT electrodes provide a stable and sensitive platform for insulin detection.
- These CNT-based electrodes are promising for diabetes-related applications, including analysis of therapeutic insulin and islet quality assessment.