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A Biosensor for Urea from Succinimide-Modified Acrylic Microspheres Based on Reflectance Transduction
School of Chemical Sciences and Food Technology, Faculty of Science and Technology, University Kebangsaan Malaysia, Bangi, Selangor 43600, Malaysia
* Author to whom correspondence should be addressed.
Received: 25 July 2011; in revised form: 2 August 2011 / Accepted: 4 August 2011 / Published: 26 August 2011
Abstract: New acrylic microspheres were synthesised by photopolymerisation where the succinimide functional group was incorporated during the microsphere preparation. An optical biosensor for urea based on reflectance transduction with a large linear response range to urea was successfully developed using this material. The biosensor utilized succinimide-modified acrylic microspheres immobilized with a Nile blue chromoionophore (ETH 5294) for optical detection and urease enzyme was immobilized on the surface of the microspheres via the succinimide groups. No leaching of the enzyme or chromoionophore was observed. Hydrolysis of the urea by urease changes the pH and leads to a color change of the immobilized chromoionophore. When the color change was monitored by reflectance spectrophotometry, the linear response range of the biosensor to urea was from 0.01 to 1,000 mM (R2 = 0.97) with a limit of detection of 9.97 mM. The biosensor response showed good reproducibility (relative standard deviation = 1.43%, n = 5) with no interference by major cations such as Na+, K+, NH4+ and Mg2+. The use of reflectance as a transduction method led to a large linear response range that is better than that of many urea biosensors based on other optical transduction methods.
Keywords: urea; reflectance; optical biosensor; succinimide; acrylic microspheres; photopolymerisation
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MDPI and ACS Style
Ulianas, A.; Heng, L.Y.; Ahmad, M. A Biosensor for Urea from Succinimide-Modified Acrylic Microspheres Based on Reflectance Transduction. Sensors 2011, 11, 8323-8338.
Ulianas A, Heng LY, Ahmad M. A Biosensor for Urea from Succinimide-Modified Acrylic Microspheres Based on Reflectance Transduction. Sensors. 2011; 11(9):8323-8338.
Ulianas, Alizar; Heng, Lee Yook; Ahmad, Musa. 2011. "A Biosensor for Urea from Succinimide-Modified Acrylic Microspheres Based on Reflectance Transduction." Sensors 11, no. 9: 8323-8338.