Biosensor for aluminium(III) based on its inhibition of α-chymotrypsin immobilized on a screen-printed carbon electrode modified with gold nanoparticles

We report on an amperometric assay for Al(III) ions that is based on the inhibition of the enzyme alpha-chymotrypsin. Screen-printed carbon electrodes modified with gold nanoparticles were used as solid supports for the immobilization of the enzyme. The amperometric response of the synthetic enzyme substrate substrate N-benzoyl-L-tyrosine ethyl ester is affected by Al(III) ions, and this leads to a decrease in the amperometric oxidation current. The assay has a detection limit of 3.3 mu M of Al(III). The repeatability and reproducibility of the method are 6.9% (n = 3) and 6.4% (n = 5), respectively. Main interferents include Mo(VI), W(VI) and Fe(III) ions. The method was successfully applied to the determination of Al(III) in tap water.