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Volume 19 (2005), Issue 2, Pages 119-126

Glucose biosensor based on entrapment of glucose oxidase and myoglobin in silica gel by the sol-gel method

Mohammed A. Zaitoun1,2

1Chemistry Department, Mutah University, PO Box 10, Karak, Jordan
2Salalah College of Education, PO Box 3093, Salalah 211, Oman

Copyright © 2005 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A spectrophotometric method is presented to determine glucose employing the sol-gel technique. Myoglobin (Mb) and glucose oxidase are encapsulated in a transparent and porous silica glass. The produced gel (xerogel) is then immersed in water where increments of glucose are added to the solution with stirring; glucose diffuses into the sol-gel glass pores and a series of reactions take place. Glucose is first oxidized by glucose oxidase and oxygen to gluconate and hydrogen peroxide is generated. The liberated hydrogen peroxide oxidizes the Mb heme (Fe2+ into Fe3+). The higher is the glucose concentration added, the more is the H2O2 generated, and the more is the Mb oxidation (Fe2+ to Fe3+) and as a result the higher is the absorbance at 400 nm (negative peak, lower absorbance value). All measurements are performed at this wavelength (400 nm), the negative peak obtained by subtracting the absorption spectra of Mb before and after oxidation. Measuring the slope of the absorbance decay versus time at 400 nm monitors increments of added glucose. Each glucose concentration has an accompanying unique decay curve with a unique slope. The higher is the glucose concentration; the steeper is the decay curve (higher slope value). The calibration curve was linear up to 40 mM.