High stability potentiometric urea biosensor based on enzyme attached nanoparticles

Highly stable new urea biosensor was prepared by using poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) nanoparticles, which was used as a nano-carrier for urease enzyme. The urea biosensor was prepared by an ammonium selective electrode along with the urease immobilized nanoparticles. Synthesized nanoparticles were characterized by SEM and attachment of the enzyme onto the nanoparticles was evaluated by EDX analysis. Potentiometric response of the biosensor was examined as a function of the different concentrations of urea solution, and linear concentration range of urea was demonstrated in the range of 0.01 mM-500 mM. The detection limit was also investigated and measured as 0.77 µM. Response time of the biosensor was also determined as 30 s. Repeatability of the urea biosensor system was found to be very high, and it was demonstrated that response of the urea sensor was protected by 95.7% at the end of the 170th reuse. This biosensor system protected 83% of its initial activity at the end of the 90 day storage. Additionally, interference profile of the urea biosensor was tested against the common interferents such as ascorbic acid (AA), uric acid (UR), glucose (GL) and sodium ions (Na+), and the response of these interfering agents was found to be as negligible. Also, applicability of the synthesized urea sensor for detection of urea from artificial human serum was demonstrated.