Thick-film potentiometric biosensor for bloodless monitoring of hemodialysis

A potentiometric complete bioelectrochemical cell manufactured in an integrated strip format has been applied as dialysate urea nitrogen (DUN) biosensor. Both the urea enzyme electrode and reference electrode have been fabricated only by means of screen-printing. This thick-film DUN-biosensor has been applied as detector in a double-channel flow injection analysis (FIA) system. Under optimized conditions the determination range offered by this system covers urea levels in postdialysate fluid. The frequency of analysis is at least 12 samples of postdialysate per hour without any additional sample pretreatment. The results of analysis performed with the DUN-biosensor/FIA system are comparable with those obtained using the reference method. The system has been tested as a prototype of discrete on-line monitor of urea in spent dialysate. The DUN-time profiles are useful for evaluation of initial and final toxin levels, toxin reduction ratio, total toxin removal and other biomedical parameters important for quantitative description of intra- and inter-session periods of hemodialysis (HD) therapy. Examples of HD monitoring and modeling using the developed system are demonstrated.