Orienting DNA helices on gold using applied electric fields

2019-10-19 04:53:05

DNA potential applied Aring helices

责任者: Kelley, S.O.;Barton, J.K.;Jackson, N.M.;McPherson, L.D.;Potter, A.B.;Spain, E.M.;Allen, M.J.;Hill, M.G. 单位: Div. of Chem. & Chem. Eng., California Inst. of Technol., Pasadena, CA, USA 来源出处: Langmuir(Langmuir (USA)),1998/11/24,14(24):6781-4 摘要: Gold surfaces modified with thiol-derivatized DNA duplexes have been investigated as a function of applied electrochemical potential via atomic force microscopy (EC-AFM). At open circuit, monolayers of well-packed DNA helices form with a film depth of 45(3) Å. On the basis of the anisotropic dimensions of these 15 base pair duplexes (20 Å in diameter versus 50 Å in length), this corresponds to an average ~45° orientation of the helical axis with respect to the gold surface. Under potential control, the monolayer thickness (and therefore the orientation of the helices) changes dramatically with applied potential. At potentials negative of ~0.45 V (versus a Ag wire quasi-reference electrode) film thicknesses of ~55 Å are observed, whereas at more positive potentials the monolayer thickness drops to a limiting value of ~20 Å. These results are consistent with a morphology change in which the helices either stand straight up or lie flat down on the metal surface, depending on the electrode potential relative to the potential of zero charge (pzc). This voltage-induced morphology change is reversible and effectively constitutes a nanoscale mechanical “switch” 关键词: atomic force microscopy;DNA;electrochemistry;molecular biophysics;molecular reorientation;monolayers;surface chemistry;surface structure;DNA helices;gold;applied electric fields;thiol-derivatized DNA duplexes;applied electrochemical potential;atomic force microscopy;open circuit;monolayers;anisotropic dimensions;helical axis;monolayer thickness;orientation;metal surface;electrode potential;voltage-induced morphology change;nanoscale mechanical switch;0.45 V;Au