Abstract: Electrochemical quartz crystal microbalance(EQCM), which is capable of sensitive measurement for mass and electrochemical signals, was employed to study cytochrome c. Self-assembled monolays(SAMs) with carboxy groups were first coated on the gold electrode of a quartz crystal resonator by adsorption of ω-mercaptoundecanoic acid(MUA), cytochrome c was then covalently attached to the surface via N-ethyl-N'- carbodiimide hydrochloride(EDC) and N-hydroxysuccinimide(NHS). The processes for self-assembly of MUA and immobilization of cytochrome c were both real-time characterized. And the surface coverage densities of MUA and cytochrome c were estimated to be 3.73×10^-9 and 7.31×10^-11 mol/cm², respectively. The amount of cytochrome c was found to be proportional to the frequency changes between 0.03 μmol/L and 3.0 μmol/L, with a regression equation Δf(Hz)=50.19 c(Cyt C)+67.07(r²=0.998), and the limit of detection of 1.19×10^-9 mol/L was also attained.

Key words: Self-assembled monolayers(SAMs), Cytochrome c, Electrochemical quartz crystal microbalance(EQCM)