L. Profils-de-topographie-et-de-phase-sont-indiqués-sur-la-figure and B. , 02 dans le cas de l'ADN directement posé sur la surface terminée amine Pour chaque ligne de l'image, on repère le minimum de la phase, la hauteur de la corde de l'ADN et la phase correspondante au maximum en topographie de l'ADN (cf. figure B.02) On trace sur les figures B.03 et B.04 les deux valeurs de la phase obtenues pour chaque ligne de l'image, en fonction

. Dans-ce-cas, on voit clairement une dépendance entre la phase et la hauteur mesurée (cf. figures B.03 et B.04) On observe le même niveau de dispersion pour les hauteurs que dans le cas de l'ADN sur la surface terminée amine, Cette dépendance est la plus nette entre le minimum de la phase et la hauteur de la corde d'ADN (cf. figure B.03 en b) et B.04 en b))

P. Cette-méthode, ADN en fonction du niveau d'enroulement de la molécule On peut également accéder aux forces mises en jeu. Lorsque la protéine interagit avec l'ADN, la molécule est soit allongée ou compactée. On peut également suivre le niveau d'enroulement de la molécule. On donne sur la figure D.01, l'allure d'une courbe de force

D. Ainsi and . Formes-coexistent-sur-le-brin, Une zone en forme B et une zone en forme P ou dénaturé. L'allure des courbes de force évolue continûment en fonction de la torsion On constate que ces courbes de force sont une combinaison linéaire de celle de l'ADN forme P ou dénaturé et de l'ADN forme B. On a la relation Lp(F) = (?/? forme i )L (? forme i) + (1-?/? forme i )L (?=0) , où i correspond à l'ADN dénaturé ou en forme P (? dénaturé =-1 et ? P =3) On en déduit ainsi certaines caractéristiques structurales de l, ADN P : 2.6 paire de base par tour d'hélice, 2.38nm entre les paires de base (L'ADN P est 1.75 fois plus long que l'ADN B). La forme P avec les bases orientées vers l'extérieur fait penser à la forme proposé par Pauling, 1953.

. Liu, Il faut noter que les protéines peuvent exercer des forces de l'ordre de 1-10pN sur l'ADN, forces suffisantes pour faire apparaître cette nouvelle phase

J. F. Allemand, D. Bensimon, L. Jullien, A. Bensimon, and V. , pH-dependent specific binding and combing of DNA, Biophysical Journal, vol.73, issue.4, pp.2064-2070, 1997.
DOI : 10.1016/S0006-3495(97)78236-5

P. Allongue, C. H. De-villeneuve, S. Morin, R. Boukherroub, and D. D. Wayner, The preparation of flat H???Si(111) surfaces in 40% NH4F revisited, Electrochimica Acta, vol.45, issue.28, pp.4591-98, 1989.
DOI : 10.1016/S0013-4686(00)00610-1

A. Aviram and M. , Ratner Molecular Electronics Science and Technology Annals of the, New York Academy of Sciences, vol.852, pp.1-372, 1998.

C. D. Bain, E. B. Troughton, Y. Tayo, J. Evall, G. M. Whitesides et al., Formation of monolayer films by the spontaneous assembly of organic thiols from solution onto gold, Journal of the American Chemical Society, vol.111, issue.1, p.321, 1989.
DOI : 10.1021/ja00183a049

J. Bardeen, Tunnelling from a Many-Particle Point of View, Physical Review Letters, vol.6, issue.2, p.57, 1961.
DOI : 10.1103/PhysRevLett.6.57

J. Barrat and J. , Joanny Advances in Chemical Physcis, pp.16-20, 1996.

W. Bartholtt and C. , Purity of the sacred lotus, or escape from contamination in biological surfaces, Planta, vol.202, issue.1, pp.1-8, 1997.
DOI : 10.1007/s004250050096

J. Bednar, P. Furrer, and A. Stasiak, The Twist, Writhe and Overall Shape of Supercoiled DNA Change During Counterion-induced Transition from a Loosely to a Tightly Interwound Superhelix, Journal of Molecular Biology, vol.235, issue.3, pp.825-847, 1989.
DOI : 10.1006/jmbi.1994.1042

T. B. Beebe-jr, T. E. Wilson, D. F. Ogletree, J. E. Katz, R. Balhorn et al., Direct observation of native DNA structures with the scanning tunneling microscope, Science, vol.243, issue.4889, pp.370-372, 1989.
DOI : 10.1126/science.2911747

A. Bensimon, A. Simon, A. Chiffaudel, V. Croquette, F. Heslot et al., Alignment and sensitive detection of DNA by a moving interface, Science, vol.265, issue.5181, pp.2096-98, 1994.
DOI : 10.1126/science.7522347

G. Binning, H. Roher, C. Berger, and E. Weibel, Surface Studies by Scanning Tunneling Microscopy, Physical Review Letters, vol.49, issue.1, p.57, 1982.
DOI : 10.1103/PhysRevLett.49.57

M. Bixon and J. Jortner, Charge Transport in DNA Via Thermally Induced Hopping, Journal of the American Chemical Society, vol.123, issue.50, pp.12556-12567, 2001.
DOI : 10.1021/ja010018p

H. Bottger, V. V. Bryskin-]-l, J. N. Bottomley, D. P. Haseltine, R. J. Allison et al., Hooping Conduction in Solids Akademie-Verlag, Ferrel J. Vac. Sci. Technol. A, vol.10, issue.4, pp.591-594, 1985.

J. B. Brzoska, N. Shahidzadeh, and F. Rondelez, Evidence of a transition temperature for the optimum deposition of grafted monolayer coatings, Nature, vol.360, issue.6406, p.719, 1992.
DOI : 10.1038/360719a0

R. Bruinsma, G. Gruner, M. R. D-'orsogona, J. A. Rudnick-]-n, R. J. Burnham et al., Fluctuation-Facilitated Charge Migration along DNA, Physical Review Letters, vol.85, issue.20, pp.4393-4396, 1992.
DOI : 10.1103/PhysRevLett.85.4393
URL : http://arxiv.org/abs/cond-mat/0005200

D. Courjon and C. , Bainier Le champ proche optique, théorie et applications, 1995.

J. E. Coury, L. Mcfail-isom, S. Presnell, L. D. Williams, and L. A. Bottomley, Scanning probe visualization of electrostatically immobilized intercalating drug???nucleic acid complexes, Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, vol.13, issue.3, pp.1746-1751, 1995.
DOI : 10.1116/1.579763

J. E. Coury, J. R. Anderson, L. Mcfail-isom, L. D. Williams, and L. A. Bottomley, -phenanthroline)ruthenium(II) as a Test for a New Assay, Journal of the American Chemical Society, vol.119, issue.16, pp.3792-3796, 1997.
DOI : 10.1021/ja9623774
URL : https://hal.archives-ouvertes.fr/hal-00851725

L. Couture and R. , Zitoun Physique statistique, 1992.

H. Dai, J. H. Hafner, A. G. Rinzler, D. T. Colbert, R. E. Smalley-]-p et al., Cees Dekker and Mark A. Ratner Physics World, José M. Soler, and Emilio Artacho Physical Review Letters, pp.56-85, 1971.

E. Emberly and G. Kirczenow, State Orthogonalization by Building a Hilbert Space: A New Approach to Electronic Quantum Transport in Molecular Wires, Physical Review Letters, vol.81, issue.23, p.5205, 1998.
DOI : 10.1103/PhysRevLett.81.5205

Y. Fang and J. H. Hoh, Surface-directed DNA condensation in the absence of soluble multivalent cations, Nucleic Acids Research, vol.26, issue.2, pp.588-593, 1998.
DOI : 10.1093/nar/26.2.588

V. Ferreiro, Y. Pennec, R. Seguela, and G. Coulon, Shear banding in polyamide 6 films as revealed by atomic force microscopy, Polymer, vol.41, issue.4, pp.1561-69, 1999.
DOI : 10.1016/S0032-3861(99)00276-1

M. Freitag, M. Radosavljevic, W. Clauss, and A. T. , Local electronic properties of single-wall nanotube circuits measured by conducting-tip AFM, Physical Review B, vol.62, issue.4, pp.2307-2310, 1984.
DOI : 10.1103/PhysRevB.62.R2307

K. Fukui and H. Onishi, Imaging of atomic-scale structure of oxide surfaces and adsorbed molecules by noncontact atomic force microscopy, Applied Surface Science, vol.140, issue.3-4, pp.259-264, 1999.
DOI : 10.1016/S0169-4332(98)00537-6

J. Gu, S. Tanaka, Y. Otsuka, H. Tabata, and T. Kawai, Self-assembled dye-DNA network and its photoinduced electrical conductivity, Applied Physics Letters, vol.80, issue.4, pp.688-690, 2002.
DOI : 10.1063/1.1435805

J. Gu, L. Cai, S. Tanaka, and Y. Otsuka, Electric conductivity of dye modified DNA films with and without light irradiation in various humidities, Journal of Applied Physics, vol.92, issue.5, pp.2816-2820, 2000.
DOI : 10.1063/1.1498959

M. Guéron, J. Ph, and M. Demaret, A Unified Theory of the B-Z Transition of DNA in High and Low Concentrations of Multivalent Ions, Biophysical Journal, vol.78, issue.2, pp.1070-1083, 2000.
DOI : 10.1016/S0006-3495(00)76665-3

H. G. Hansma, I. Revenko, K. Kim, and E. Daniel, Atomic Force Microscopy of Long and Short Double-Stranded, Single-Stranded and Triple-Stranded Nucleic Acids, Nucleic Acids Research, vol.24, issue.4, pp.713-720, 1996.
DOI : 10.1093/nar/24.4.713

H. Hölscher, U. D. Schwarz, and R. , Calculation of the frequency shift in dynamic force microscopy, Applied Surface Science, vol.140, issue.3-4, pp.344-351, 1999.
DOI : 10.1016/S0169-4332(98)00552-2

P. J. James, M. Antognozzi, J. Tamayo, T. J. Mcmaster, J. M. Newton et al., Interpretation of Contrast in Tapping Mode AFM and Shear Force Microscopy. A Study of Nafion, Langmuir, vol.17, issue.2, pp.349-360, 2001.
DOI : 10.1021/la000332h

M. R. Seong-ho-kang, E. S. Shortreed, and . Yeung, Real-Time Dynamics of Single-DNA Molecules Undergoing Adsorption and Desorption at Liquid???Solid Interfaces, Analytical Chemistry, vol.73, issue.6, pp.1091-1099, 2000.
DOI : 10.1021/ac0013599

S. O. Kelley, N. M. Jackson, M. G. Hill, and J. K. Barton, Long-Range Electron Transfer through DNA Films, Angewandte Chemie International Edition, vol.38, issue.7, pp.941-945, 1959.
DOI : 10.1002/(SICI)1521-3773(19990401)38:7<941::AID-ANIE941>3.0.CO;2-7

L. Landau and E. Mir, Lifchitz Physique théorique TOME 6 : Mécanique des fluides, éditions, p.223, 1957.

G. Lee, P. G. Arscott, V. A. Bloomfield, and D. Evans, Scanning tunneling microscopy of nucleic acids, Science, vol.244, issue.4903, pp.475-477, 1989.
DOI : 10.1126/science.2470146

A. G. Leslie, S. Arnott, R. Chandrasekaran, and R. L. Ratliff, Polymorphism of DNA double helices, Journal of Molecular Biology, vol.143, issue.1, pp.49-72, 1980.
DOI : 10.1016/0022-2836(80)90124-2

M. R. Linford and C. E. Chidsey, Alkyl monolayers covalently bonded to silicon surfaces, Journal of the American Chemical Society, vol.115, issue.26, p.12631, 1993.
DOI : 10.1021/ja00079a071

F. Livolant, A. M. Levelut, J. Doucet, and J. P. , The highly concentrated liquid-crystalline phase of DNA is columnar hexagonal, Nature, vol.339, issue.6227, pp.724-726, 1989.
DOI : 10.1038/339724a0

Y. Maeda, T. Matsumoto, and T. , Observation of single- and double-stranded DNA using non-contact atomic force microscopy, Applied Surface Science, vol.140, issue.3-4, pp.400-405, 1978.
DOI : 10.1016/S0169-4332(98)00562-5

E. Margeat, C. L. Grimellec, C. A. Royer-]-s, K. Matsumoto, M. Morikawa et al., Visualization of trp Repressor and its Complexes with DNA by Atomic Force Microscopy, Thèse université Lille 1, pp.2712-2720, 1968.
DOI : 10.1016/S0006-3495(98)77715-X

O. Melnyk, X. Duburcq, C. Olivier, F. Urbès, C. Auriault et al., Peptide Arrays for Highly Sensitive and Specific Antibody-Binding Fluorescence Assays, Bioconjugate Chemistry, vol.13, issue.4, pp.713-720, 1997.
DOI : 10.1021/bc015584o

L. Nony, R. Boisgard, and J. ?. , DNA Properties Investigated by Dynamic Force Microscopy, Biomacromolecules, vol.2, issue.3, pp.827-835, 1999.
DOI : 10.1021/bm0100209
URL : https://hal.archives-ouvertes.fr/hal-00004532

L. Nony, R. Boisgard, and J. P. , Nonlinear dynamical properties of an oscillating tip???cantilever system in the tapping mode, The Journal of Chemical Physics, vol.111, issue.4, pp.1615-1627, 1999.
DOI : 10.1063/1.479422
URL : https://hal.archives-ouvertes.fr/hal-00011145

D. T. Odom, E. A. Dill, and J. K. , Robust charge transport in DNA double crossover assemblies, Chemistry & Biology, vol.7, issue.7, pp.475-481, 1993.
DOI : 10.1016/S1074-5521(00)00133-2

Y. Okahata, T. Kobayashi, H. Nakayama, and K. , DNA-aligned cast film and its anisotropic electron conductivity, Supramolecular Science, vol.5, issue.3-4, pp.317-320, 1998.
DOI : 10.1016/S0968-5677(98)00025-X

Y. Okahata, T. Kobayashi, K. Tanaka, and S. , Anisotropic Electric Conductivity in an Aligned DNA Cast Film, Journal of the American Chemical Society, vol.120, issue.24, pp.6165-6166, 1995.
DOI : 10.1021/ja980165w

M. Olvera-de-la-cruz, L. Belloni, M. Delsanti, J. P. Dalbiez, O. Spalla et al., Precipitation of highly charged polyelectrolyte solutions in the presence of multivalent salts, The Journal of Chemical Physics, vol.103, issue.13, pp.5781-5791, 1949.
DOI : 10.1063/1.470459

E. Raspaud, M. Olvera-de-la-cruz, J. Sikorav, and F. , Precipitation of DNA by Polyamines: A Polyelectrolyte Behavior, Biophysical Journal, vol.74, issue.1, pp.381-393, 1994.
DOI : 10.1016/S0006-3495(98)77795-1

C. Rivetti, M. Guthold, and C. Bustamante, Ioulia Rouzina and Victor A, J. Mol. Biol. Bloomfield J. Phys. Chem, vol.264, issue.100, pp.919-932, 1996.

I. Rouzina and V. A. Bloomfield, Influence of Ligand Spatial Organization on Competitive Electrostatic Binding to DNA, The Journal of Physical Chemistry, vol.100, issue.10, pp.4305-4313, 1996.
DOI : 10.1021/jp9525907

I. Rouzina and V. A. Bloomfield, Macroion Attraction Due to Electrostatic Correlation between Screening Counterions. 1. Mobile Surface-Adsorbed Ions and Diffuse Ion Cloud, Munlika Satjapipat, Raymond Sanedrin, and Feimeng Zhou Langmuir, pp.9977-9989, 1984.
DOI : 10.1021/jp960458g

A. Schulz, N. Mücke, J. Langowski, and K. Rippe, Scanning force microscopy of Escherichia coli RNA polymerase????54 holoenzyme complexes with DNA in buffer and in air, Journal of Molecular Biology, vol.283, issue.4, pp.821-836, 1991.
DOI : 10.1006/jmbi.1998.2131

F. C. Simmel and B. Yurke, A DNA-based molecular device switchable between three distinct mechanical states, Applied Physics Letters, vol.80, issue.5, pp.883-885, 2001.
DOI : 10.1063/1.1447008

E. A. Smith, M. J. Wanat, Y. Cheng, V. P. Sérgio, A. G. Barreira et al., Formation, Spectroscopic Characterization, and Application of Sulfhydryl-Terminated Alkanethiol Monolayers for the Chemical Attachment of DNA onto Gold Surfaces, Langmuir, vol.17, issue.8, pp.2502-2507, 1999.
DOI : 10.1021/la001064q

P. Sottas, E. Larquet, A. Stasiak, and J. Dubochet, Brownian Dynamics Simulation of DNA Condensation, Biophysical Journal, vol.77, issue.4, pp.1858-1870, 1999.
DOI : 10.1016/S0006-3495(99)77029-3

T. R. Strick, J. Allemand, D. Bensimon, and V. , Behavior of Supercoiled DNA, Biophysical Journal, vol.74, issue.4, pp.2016-2028, 1998.
DOI : 10.1016/S0006-3495(98)77908-1

T. Strother, W. Cai, X. Zhao, R. J. Hamers, and L. M. Smith, Synthesis and Characterization of DNA-Modified Silicon (111) Surfaces, Journal of the American Chemical Society, vol.122, issue.6, pp.1205-1209, 2000.
DOI : 10.1021/ja9936161

T. Thundat, D. P. Allison, and R. J. Warmack, Stretched DNA structures observed with atomic force microscopy, Nucleic Acids Research, vol.22, issue.20, pp.4224-4228, 1994.
DOI : 10.1093/nar/22.20.4224
URL : http://doi.org/10.1093/nar/22.20.4224

P. Tran, B. Alavi, and G. , -DNA Double Helix, Physical Review Letters, vol.85, issue.7, pp.1564-1567, 2000.
DOI : 10.1103/PhysRevLett.85.1564
URL : https://hal.archives-ouvertes.fr/hal-00309730

T. Uchihashi, M. Tanigawa, M. Ashino, Y. Sugawara, K. Yokoyama et al., ] A.Ulman An introduction to ultrathin organic films, pp.1349-1353, 1991.

J. M. Warman, P. Matthijs, and . De-haas, DNA: a molecular wire?, Chemical Physics Letters, vol.249, issue.5-6, pp.319-322, 1996.
DOI : 10.1016/0009-2614(95)01429-2

M. Washizu and O. Kurosawa, Electrostatic manipulation of DNA in microfabricated structures, IEEE Transactions on Industry Applications, vol.26, issue.6, pp.1165-1172, 1990.
DOI : 10.1109/28.62403

J. D. Watson and F. H. , Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, Nature, vol.9, issue.4356, p.737, 1953.
DOI : 10.1016/0006-3002(53)90232-7

R. E. Williams, Gallium arsenide processing techniques, 1984.