Abstract
An amperometric biosensor was fabricated for the quantitative determination of urea in aqueous medium using hematein, a pH-sensitive natural dye. The urease (Urs) was covalently immobilized onto an electrode made of gold nanoparticles functionalized with hyperbranched polyester-Boltron® H40 (H40-Au) coated onto an indium-tin oxide (ITO) covered glass substrate. The covalent linkage between the Urs enzyme and H40-Au nanoparticles provided the resulting enzyme electrode (Urs/H40-Au/ITO) with a high level of enzyme immobilization and excellent lifetime stability. The response studies were carried out as a function of urea concentration with amperometric and photometric measurements. The biosensor based on Urs/H40-Au/ITO as the working electrode showed a linear current response to the urea concentration ranging from 0.01 to 35 mM. The urea biosensor exhibited a sensitivity of 7.48 nA/mM with a response time of 3 s. The Michaelis-Menten constant for the Urs/H40-Au/ITO biosensor was calculated to be 0.96 mM, indicating the Urs enzyme immobilized on the electrode surface had a high affinity to urea.
Original language | English (US) |
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Pages (from-to) | 1401-1407 |
Number of pages | 7 |
Journal | Talanta |
Volume | 78 |
Issue number | 4-5 |
DOIs | |
State | Published - Jun 15 2009 |
Keywords
- Amperometric detection
- Boltron H40
- Covalent immobilization
- Gold nanoparticles
- Urea biosensor
ASJC Scopus subject areas
- Chemistry(all)