| We present the study of the self-assembly monolayers of selenocystine (SeCys SAMs) on gold surface. The formation of the monolayers and electrode interfacial capacitance by cyclic voltammetry with Fe(CN)63- as a probe were investigated and wettability of SeCys SAMs film on gold surface was studied. The results indicated that the dense and steady SeCys SAMs film formed when gold electrode immersing into selenocystine of pH 1.2 at room temperature for 30 hours. Contact angle ofSeCys SAMs surface is 36±4° and SeCys SAMs surface is more hydrophilic than baregold surface.Electrochemical behaviors of Cu2+, Zn2+, Cd2+, Fe3+, Ca2+ and Mg2+ on SeCys SAMs/Au electrode were studied with cyclic voltammetry. With potential scans ranged from -0.4V or more negative to 0.6V, SeCys exists on Au electrode surface stably and there was complexation between Cu2+ of lower concentration (1.0×10-5 mol/L ) and SeCys on electrode surface; For Zn2+ and Cu2+ of higher concentration(>1.0× 10-3mol/L), a part of them can take part in complex reaction with SeCys on electrode surface, and others transport and discharge taking place on Au substrate surface accessible through SeCys SAMs; In addition, SeCys SAMs on Au electrode prohibit charge transfer of the Cd2+ and Fe3+. With potential scans ranged from -0.4V or more negative tol.4V, SeCys desorbs from Au electrode surface; For all metal ions including electrochemical active metal ions: Cu2+, Zn2+, Fe3+, Cd2+ and electrochemical inactive metal ions: Ca2+, Mg2+, reduction peaks at 0.05V～0.28V were observed, and it was proposed that there was complexation between Se atom of SeCys and all metal ions.Furthermore, Electrochemical behaviors of Fe(CN)63-,Cr2O72- on SeCys SAMs/Au electrode were studied, and adsorption of I-, Cl- on bare Au electrode and SeCys SAMs/Au electrode were compared. The results indicated that SeCys SAMs on Au electrode prohibit charge transfer of Fe(CN)63-, Cr2O72- and catalyze the adsorption of I-,Cl-.
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