Electrochemical biosensor for creatinine based on the immobilization of creatininase, creatinase and sarcosine oxidase onto a ferrocene/horseradish peroxidase/gold nanoparticles/multi-walled carbon nanotubes/Teflon composite electrode

摘要

A composite electrode consisted of gold nanoparticles (AuNPs), multi-walled carbon nanotubes (MWC-NTs) and Teflon, to which peroxidase (HRP) and ferrocene (Fc) were incorporated as auxiliary enzyme and redox mediator, respectively, was constructed. The enzymes creatininase, creatinase and sarcosine oxidase were then co-immobilized onto the surface of the resulting HRP/Fc/AuNPs/MWCNTs/Teflon electrode for the preparation of a creatinine biosensor. Amperometry in stirred solutions using a detection potential of 0.0 V vs Ag/AgCl allowed a linear calibration plot to be obtained in the 0.003-1.0 mM creatinine concentration range with a limit of detection of 0.1 μM (S/N = 3). The apparent Michaelis-Menten constant for creatininase was K_M~(ap) = 4.1 ± 0.4 mM. The developed biosensor was validated with good results by determining creatinine in human serum and correlating with the spectrophotometric Jaffe's method.