Measurement of urea, creatinine and urea to creatinine ratio using enzyme based chemical current conveyor (CCCII+)

A system potentially capable of providing continuous analogue computation of (i) urea concentration, (ii) creatinine concentration and (iii) urea-to-creatinine ratio, important markers for the prediction of renal failure is described. The system utilises two enzyme modified chemical current-conveyors, CCCII+, to obtain the outputs directly related to the urea and creatinine concentrations. The devices have been separately prepared by immobilising urease and creatinine deiminase (CD) enzymes onto the input ISFET surfaces. The primary experimental results of the system demonstrate a linear response covering a normal physiological range of urea between 2.5 and 8.3 mM and creatinine between 44 and 106 μM. We propose that this system has the potential for real-time monitoring and suitable for medical determination for renal dysfunctionality.