Polypyrrole/polyethylenimine Hybrid Film with Improved Potentiometric Response for Urea Sensing Application

This paper presents the fabrication a novel polypyrrole/polyethylenimine (PPy/PEI) hybrid film and its utilization as a potentiometric transducer in urea biosensor. Modification of PPy has been achieved via plasma polymerization of polyethylenimine (PEI) leading to increased number of free amino group (-NH2) on the surface of PPy. Subsequently, urease, selective catalytic enzyme for urea, has been covalently immobilized on the surface of PPy/PEI hybrid film. A combination of various techniques including CV and XPS was performed in order to confirm the existence of PEI and urease on the PPy film. Potentiometric responses of the PPy/PEI hybrid film showed the sensitivity of 56.15 mV/pUrea (r2 > 0.995) over the urea concentration ranging from 5.0×10-1 mM to 10.0 mM (pUrea 2.0-3.3). Detection limits and response linearity was in the normal range of urea level. The response time was approximately 30 seconds. Leaching test revealed that the PPy/PEI hybrid film showed minimal urease leaching out of the film during measurement, indicating that the PPy/PEI hybrid film can be a great alternative urea biosensor. The results of urea determination in standard urea solutions, blood and urine obtained by the PPy/PEI hybrid film correlated well with those obtained by a spectrophotometric method.