Improvement of urease based biosensor characteristics using additional layers of charged polymers

Enzymatic sensors with urease immobilized on the surface of ion sensitive h eld effect transistors (ISFETs) were developed. Covering the immobilized enzyme with a charged polymer layer increases sens itivity and stability of the urea specific biosensor. Urease immobilization under a negatively charged polymer induces an increase of the inhibition e ffect of the heavy metal ions due to the cation accumulation in the polymer ic matrix. On the other hand a positively charged additional membrane prote cts the bioselective material from positively charged heavy metal ions. Such developed enzymatic biosensors can be used for the analysis of trace l evels of heavy metal ions in water samples through inhibition mechanisms. T hus, the concentrations of some heavy metal ions as low as 1 mu M and lower can be detected. (C) 2000 Elsevier Science B.V. All rights reserved.