A novel conductometric creatinine biosensor based on solid-state contact ammonium sensitive PVC–NH2 membrane

A novel, highly sensitive and stable conductometric biosensor for creatinine determination is developed. The biosensor is based on solid-state contact ammonium-sensitive sensor. Creatininase is chemically immobilized on the surface of the solid-state contact ammonium-sensitive membrane via glutaraldehyde covalent attachment method. The developed conductometric creatinine biosensors demonstrate high sensitivity and short response time toward creatinine. The detection limit of the biosensor was about 2 × 10−6 M and the response time was shorter than 10 s in phophate buffer solution at pH 7.20. The linear dynamic range of the biosensor was between 1 × 10−1 and 9 × 10−6 M creatinine concentration in phosphate buffer solution at pH 7.20. The biosensor exhibited good operational and storage stability for at least 4 weeks kept in dry at 4–6 °C. It had a reproducible and stable response during continuous work at least for 10 h with the relative standard deviation of 0.5% (n = 48) for creatinine of 1 × 10−3 M in phosphate buffer solution.

► This study reports a novel, highly sensitive and stable conductometric biosensor. ► The biosensor was based on solid-state contact ammonium-sensitive membrane sensor chip. ► Creatininase was chemically immobilized on the surface of the ammonium sensitive membrane. ► The biosensor exhibited reproducible and stable response at least for 10 h. ► It also showed excellent operational and storage stability for at least 4 weeks.