고려대학교

초록/요약

Dopamine, one of the neurotransmitters in the mammalian central nervous system, plays an important role in early diagnosis of diseases. In the case of a human body, a lower level of dopamine than the usual causes Parkinson's disease and a higher level causes schizophrenia. The aim of this work is to fabricate a copper (Cu)-doped polypyrrole (PPy) based dopamine sensitive electrode. A Pt thin-film electrode(1000 {\AA}) is deposited on n-type silicon substrate(resistivity; 1 $\sim$ 10 $\Omega$$\cdot$cm, orientation; (100)) by embedding an 200 {\AA} Ti underlayer, which increases adhesive strength between the Pt thin-film and silicon dioxide. In general, tyrosinase (EC 1, 14, 15, 1) is oxidized dopamine to dopaquinone. Polypyrrole (PPy) films are electropolymerized with Cu on the Pt thin film for increasing conductivity and supporting reagent for oxidation of dopamine. In addition, tyrosinase, which is included copper in active site, is doped into the Cu-doped PPy film. The sensitivities of a normal PPy-coated dopamine sensitive electrode and the Cu-doped PPy dopamine sensitive electrode are compared by means of chronoamperometry with various dopamine concentrations. Under the optimized condition, the limiting current obtained from the Cu-doped PPy dopamine sensitive electrode is proportional to the dopamine concentrations with the slope of 0.09 $\mu$A decade$^{-1}$ in the range of 10 mmol/L to 1 mmol/L dopamine concentrations, which is a higher sensitivity value than that of the normal PPy-coated dopamine sensitive electrode. In addition, the electrode surface is analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX).