مشخصات پژوهش

Tyrosine or 4-hydroxyphenylalanine is a vital constituent of proteins and play important roles in many biochemical processes [1]. The diseases occurrence, such as Parkinson’s disease, atherosclerosis, viral infection, autoimmune disorders, and tumor, may also induce a number of amino acid metabolism enzymes to accelerate degradation of amino acids, including L-Tyr [2]. Therefore, development of the L-Tyr sensors not only is of great importance in monitoring of concentration of the L-Tyr, but also is important in detection of some diseases. A sol-gel technique was used for fabrication of a renewable carbon ceramic electrode (CCE) modified with lead powder. The lead powder was then oxidized in NaOH solution by scanning the electrode potential from -0.3 to 0.7 V vs. SCE to form a lead dioxide film electrode. The electrochemical behavior of the PbO2 modified carbon ceramic electrode (PbO2/CCE) was studied by cyclic voltammetry. Cyclic voltammetric and chronoamperometric studies showed the modified electrode to display electrocatalytic activity toward the direct oxidation of L-tyrosine and was used as an amperometric sensor. The response of the PbO2/CCE for L-tyrosine was linear in the concentration range between 0.005 and 1.46 mM with a coefficient of determination (R2) of 0.9963. The response of the modified electrode was rapid and approached 98% of the steady-state current within 5 s. The limit of detection based on signal-to-noise ratio (S/N) 3 and limit of quantification based signal-to-noise ratio (S/N) of 10 were calculated to be 0.77 and 2.56 µM, respectively. Furthermore, the PbO2/CCE modified electrode exhibits freedom of interference from other co-existing electroactive species such as L-alanine, histidine, methionine, phenylalanine, and glucose.