All Solid-State Potentiometric Biosensors for Creatinine Determination Based on pH and Ammonium Electrodes

This work investigates a disposable creatinine potentiometric biosensor based on a pH-sensitive electrode and an ammonium ion-selective electrode. An enzyme, creatinine iminohydrolase (CIH) was immobilized directly onto the surface of the electrodes by the entrapment method. According to the experimental results, the creatinine biosensors based on the pH-sensitive electrode and ammonium ion-selective electrode show a rapid response time (t(95) < 30 s) and a linear dynamic response range for creatinine determination between 40 mu M and 140 mu M. Furthermore, the ammonium ion-selective electrode-based biosensors exhibited good operational stability (over 14 times) and storage stability (over 40 days). By discussing the reproducibility and pH effects of the creatinine biosensors, features of creatinine biosensors based on ammonium ion-selective electrodes are described. Moreover, development of a low-cost, solid-state, disposable potentiometric creatinine biosensor based on pH-sensitive electrodes and ammonium ion-selective electrodes is discussed.