Modeling and Numerical Simulation of an Immobilized Enzyme Conductometric Urea Biosensor
Received: 11 February 2025 | Revised: 7 March 2025 | Accepted: 19 March 2025 | Online: 4 June 2025
Corresponding author: Sid-Ali Kouras
Abstract
In this study, a mathematical model for predicting the response of a conductometric urea biosensor was developed and numerically simulated. The biosensor features a planar interdigitated electrode array with immobilized urease. The enzymatic hydrolysis of urea generates ionic products, such as ammonium (NH₄⁺) and bicarbonate (HCO3-) ions, altering the solution's electrical conductivity. To optimize the biosensor performance, key physicochemical processes were analyzed through numerical modeling and validated against experimental data, showing strong agreement. Simulations under varying conditions supported the experimental design, improved the analytical performance, and reduced the development costs. While previous studies have explored conductometric urea biosensors, few have addressed optimizations through numerical modeling. This study addresses this gap by examining the effects of temperature, pH, enzyme layer thickness, and CO2 concentration using the COMSOL Multiphysics software. The model accurately predicted conductivity variations across different urea concentrations, with optimal responses being observed at 37 °C, 5% CO2, pH 7.4, and an enzymatic zone length of 500 µm. These results offer valuable insights for enhancing the design and application of conductometric urea biosensors in biomedical and environmental fields.
Keywords:
conductometry, urea, urease, modeling, biosensor, immobilized enzymeDownloads
References
N. F. Sheppard, D. J. Mears, and A. Guiseppi-Elie, "Model of an immobilized enzyme conductimetric urea biosensor," Biosensors and Bioelectronics, vol. 11, no. 10, pp. 967–979, 1996.
Valdes, J. J., Wall Jr, J. G., Chambers, J. P., and Eldefrawi, M. E. "A receptor-based capacitive biosensor," Johns Hopkins APL Technical Digest, vol. 9, no. 1, pp. 4-9, 1988.
R. F. Taylor, I. G. Marenchic, and E. J. Cook, "An acetylcholine receptor-based biosensor for the detection of cholinergic agents," Analytica Chimica Acta, vol. 213, pp. 131–138, 1988.
D. C. Cullen, R. S. Sethi, and C. R. Lowe, "Multi-analyte miniature conductance biosensor," Analytica Chimica Acta, vol. 231, pp. 33–40, 1990.
S. R. Mikkelsen and G. A. Rechnitz, "Conductometric tranducers for enzyme-based biosensors," Analytical Chemistry, vol. 61, no. 15, pp. 1737–1742, Aug. 1989.
M. Singh, N. Verma, A. Garg, and N. Redhu, "Urea biosensors," Sensors and Actuators B: Chemical, vol. 134, no. 1, pp. 345–351, Aug. 2008.
C.-Y. Lai, P. Foot, J. Brown, and P. Spearman, "A Urea Potentiometric Biosensor Based on a Thiophene Copolymer," Biosensors, vol. 7, no. 1, Mar. 2017, Art. no. 13.
K. Sihombing, M. C. Tamba, W. S. Marbun, and M. Situmorang, "Urease immobilized potentiometric biosensor for determination of urea," Indian Journal of Chemistry - Section A Inorganic, Physical, Theoretical and Analytical Chemistry, vol. 57A, pp. 175–180, Feb. 2018.
S. Bekkouche and M. Kadja, "Numerical Analysis of Density-Driven Reactive Flows in Hele-Shaw Cell Geometry," Engineering, Technology & Applied Science Research, vol. 10, no. 2, pp. 5434–5440, Apr. 2020.
B. Sahin and T. Kaya, "Electrochemical amperometric biosensor applications of nanostructured metal oxides: a review," Materials Research Express, vol. 6, no. 4, Jan. 2019, Art. no. 042003.
S. K. Kirdeciler et al., "A novel urea conductometric biosensor based on zeolite immobilized urease," Talanta, vol. 85, no. 3, pp. 1435–1441, Sep. 2011.
COMSOL Multiphysics. (Version 5.6), COMSOL Inc. [Online]. Available: https://www.comsol.com
T. P. Velychko et al., "A Novel Conductometric Urea Biosensor with Improved Analytical Characteristic Based on Recombinant Urease Adsorbed on Nanoparticle of Silicalite," Nanoscale Research Letters, vol. 11, no. 1, Dec. 2016, Art. no. 106.
F. Zouaoui, N. Zine, A. Errachid, and N. Jaffrezic‐Renault, "Mathematical Model and Numerical Simulation of Conductometric Biosensor of Urea," Electroanalysis, vol. 34, no. 7, pp. 1131–1140, Jul. 2022.
S. R. Eisenberg and A. J. Grodzinsky, "The Kinetics of Chemically Induced Nonequilibrium Swelling of Articular Cartilage and Corneal Stroma," Journal of Biomechanical Engineering, vol. 109, no. 1, pp. 79–89, Feb. 1987.
K. B. Ramachandran and D. D. Perlmutter, "Effects of immobilization on the kinetics of enzyme‐catalyzed reactions. II. Urease in a packed‐column differential reactor system," Biotechnology and Bioengineering, vol. 18, no. 5, pp. 685–699, May 1976.
J. K. Leypoldt and D. A. Gough, "Model of a two-substrate enzyme electrode for glucose," Analytical Chemistry, vol. 56, no. 14, pp. 2896–2904, Dec. 1984.
M. C. Zaretsky, L. Mouayad, and J. R. Melcher, "Continuum properties from interdigital electrode dielectrometry," IEEE Transactions on Electrical Insulation, vol. 23, no. 6, pp. 897–917, Dec. 1988.
H. Waheed and A. Hussain, "Effect of Polyvinyl Pyrolidone on Morphology and Performance of Cellulose Acetate Based Dialysis Membrane," Engineering, Technology & Applied Science Research, vol. 9, no. 1, pp. 3744–3749, Feb. 2019.
D. L. Filmer and T. G. Cooper, "Effect of varying temperature and pH upon the predicted rate of ‘CO2’ utilization by car☐ylases," Journal of Theoretical Biology, vol. 29, no. 1, pp. 131–145, Oct. 1970.
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Copyright (c) 2025 Sid-Ali Kouras, Ramdane Mahamdi, Naima Touafek, Fouad Kerrour

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