A penicillamine biosensor based on tyrosinase immobilized on nano-Au/PAMAM dendrimer modified gold electrode

Gold electrodes were modified with submonolayers of 3-mercaptopropionic acid and further reacted with poly(amidoamine) (PAMAM) dendrimers to obtain thin films. The high affinity of PAMAM dendrimer for nano-Au with its amine groups was used to realize the role of nano-Au as an intermediator to immobilize the enzyme of tyrosinase. The characterization of the modified electrode was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy (AFM). Tyrosinase can catalyze the oxidation of catechol to o-benzoquinone. When penicillamine was added to the solution, it reacted with o-benzoquinone to form the corresponding thioquinone derivatives, which resulted in decrease of the reduction current of o-benzoquinone. Based on this, a new electrochemical sensor for determination of penicillamine has been developed.