Urea biosensor based on the composite film of electroinactive polypyrrole and urease modified with polyanion

A urea sensor based on the composite film of electroinactive polypyrrole (PPy) and urease (Urs) modified with polyanion was fabricated by electropolymerization. This sensor showed the potential response to urea based on the detection of pH-change during the enzymatic reaction by Urs. The sensitivity of this sensor was 53 mV decade^-1 which was higher than that of the PPy film coated electrode in which Urs was entrapped physically as previously reported. The high sensitivity was considered to be attributed to the increase in the number of immobilized Urs with the covalent bonding with carboxyl groups of PAA. This urea sensor showed linear potential response between 1 × 10^-4 mol dm^-3 and 1 × 10^-1 mol dm^-3.