Hydrogel matrix for three enzyme entrapment in creatine/creatinine amperometric biosensing

Highly sensitive and stable amperometric biosensors were developed for the determination of creatine and creatinine using creatine amidinohydrolase and sarcosine oxidase for creatine and creatinine amidohydrolase, creatine amidinohydrolase and sarcosine oxidase for creatinine, respectively. The enzymes were co-immobilized in a novel stabilizing poly(carbamoyl)sulfonate (PCS)-hydrogel matrix onto the surface of a platinum working electrode for the amperometric detection of enzymatically generated hydrogen peroxide. Both sensors showed a detection limit of 0.3 μM. The sensor response has a linear range of 1–150 μM, which corresponds to the relevant physiological range for the monitoring of the kidney function. The sensors retained about 50% of their initial sensitivity after 24 h continuous flow. The storage stability at 8 °C was found to be 6 months without loss of sensitivity.