title: Amperometric creatinine biosensor for hemodialysis patients.
abstract: BACKGROUND
  Creatinine is an important clinical laboratory parameter for the evaluation of kidney function. It is essential to determine its concentration in serum of patients suffering from renal insufficiency. During hemodialysis treatment, the measurement of creatinine in the effluent dialysate or ultrafiltrate may give additional information on the efficiency of the extracorporal procedure. Therefore, enzyme sensors with co-immobilized creatinine amidohydrolase, creatine amidinohydrolase and sarcosine oxidase have been used to determine creatinine.
  
  
  METHODS
  Enzymatically generated hydrogen peroxide has amperometrically been detected at a platinum-working electrode. To exclude electroactive compounds of the sample matrix, which might interfere with the electrochemical measurement, the sensors have additionally been modified by a Nafion membrane.
  
  
  RESULTS
  Such sensors showed a linear detection range of 0.06-1.7 mg/dl for creatinine. Diluting the sample with measuring buffer, it has also been possible to measure pathological creatinine concentrations up to 11 mg/dl. A good correlation between creatinine concentrations in serum, dialysate and ultrafiltrate determined by the presented enzyme sensors and those obtained by both, conventional colorimetric Jaffé and enzymatic measurements have been achieved.
  
  
  CONCLUSIONS
  Further developments will aim at the integration of this measuring principle into the concept to low-cost disposable planar sensors.
authors.affiliation: Department of Internal Medicine, Westfalian Wilhelms-University of Münster, Albert-Schweitzer-Str. 33, 48129, Münster, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Tombach
authors.forename: J
authors.initials: J
authors.lastname: Schneider
authors.forename: F
authors.initials: F
authors.lastname: Matzkies
authors.forename: R M
authors.initials: RM
authors.lastname: Schaefer
authors.forename: G C
authors.initials: GC
authors.lastname: Chemnitius
mesh_terms: D015374:Biosensing Techniques; D003401:Creatine / Q000032:analysis; D003404:Creatinine / Q000032:analysis*; D015312:Hemodialysis Solutions / Q000032:analysis; D006801:Humans; D006435:Renal Dialysis; D015203:Reproducibility of Results
chemical_list: D015312:Hemodialysis Solutions; D003404:Creatinine; D003401:Creatine