Michael Zharnikov

Universität Heidelberg, Heidelburg, Baden-Württemberg, Germany

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Publications (228)784.2 Total impact

  • Nikolaus Meyerbröker, Michael Zharnikov
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    ABSTRACT: Patterns of nanoparticles (NPs) on solid supports are usually restricted to a particular substrate or a class of substrates. Here we present a procedure which decouples the patterning step from the target substrate, enabling the fabrication of custom designed NP assemblies on nearly any solid support, including non-flat ones. The procedure relies on a hydrogel template prepared on the primary, conductive substrate and transferred to the target support as a sacrificial nanomembrane. The template is structured by electron beam lithography (EBL) which seals predefined areas of poly(ethylene glycol) based hydrogel film, making them inert to NP deposition in contrast to pristine areas that adsorb NPs in high densities. The deposition of NPs, occurring from an aqueous solution into the transferred membrane, follows EBL generated structure, delivering the desired NP pattern on the target support after removal of the organic matrix. Efficiency and flexibility of the procedure is illustrated by creating a variety of representative submicrometer patterns of densely packed gold and silver NPs on glass, including a useful pattern of a miniaturized quick-response code. The arrangement of NPs in these patterns corresponds to the negative image of EBL generated template. This significantly reduces the exposure time for designs where large areas covered with NPs are separated by thin, NP-free stripes.
    ACS Applied Materials & Interfaces 07/2014; · 5.90 Impact Factor
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    ABSTRACT: Heteroleptic copper(II)–polypyridyl complexes with extended p-conjugated, aromatic terminal units were immobilized on glass/Si substrates to intercalate DNA and cleave it upon photoexposure. Photonuclease activity is shown to be high, well reproducible and non-destructible towards the assembled complexes.
    Chemical Communications 07/2014; · 6.38 Impact Factor
  • Frederick Chesneau, Michael Zharnikov
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    ABSTRACT: Using self-assembled monolayers (SAMs) of [1,1′;4′,1″-terphenyl]-4,4″-dimethanethiol (TPDMT) on Au as a test system and nickel as a test adsorbate, we demonstrate that the penetration of deposited metal atoms into a SAM can be completely inhibited by the preliminary formation of palladium-chloride seeding layer at the SAM–ambience interface. This layer is formed by a simple dipping procedure that takes only a few minutes. The palladium atoms in the seeding layer serve as nucleation centers for the growing metal film, staying at its bottom during the growth. In contrast, the chlorine atoms are transferred from palladium to the deposited metal, staying on the top of the growing metal film and serving as surfactants. The above approach is a perspective way to solve the well-known top contact problem at the formation of metal–SAM–metal assemblies that are of potential importance for future electronic and spintronic devices.
    The Journal of Physical Chemistry C. 06/2014; 118(24):12980–12988.
  • Frederick Chesneau, Andreas Terfort, Michael Zharnikov
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    ABSTRACT: We studied the deposition of metal atoms (Ni as a test adsorbate) on fluorinated self-assembled monolayers (SAMs) using films of perfluoroterphenyl-substituted alkanethiols, C6F5(C6F4)2(CH2)3SH (FTP3), and partly fluorinated alkanethiols, F(CF2)10(CH2)2SH (F10H2), on Au(111) as representative test systems. Unlike the F10H2 films, their FTP3 counterparts were found to stop efficiently the penetration of nickel atoms into the SAM. The primary process is the Ni-mediated loss of fluorine atoms followed by extensive cross-linking between the partly defluorinated FTP backbones. The stability of these backbones and the rapid development of the intermolecular cross-linking, affecting predominantly the topmost part of the FTP3 SAM, are the key components to hinder the metal penetration. The chemically induced cross-linking in combination with the entirely reactive SAM represents a new concept to prepare a well-defined metal film at the SAM–ambience interface. This can be useful in context of novel metal/SAM-insulator/metal assemblies that are of potential interest for electronic and spintronic applications.
    The Journal of Physical Chemistry C. 05/2014; 118(22):11763–11773.
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    ABSTRACT: Heterometallic, coordination-based, binary oligomer films were fabricated on SiOx-based solid substrates using successive layer-by-layer assembly of optically rich and redox-active polypyridyl complexes, Ru(pytpy)2·2PF6 (Ru-PT) and Os(pytpy)2·2PF6 (Os-PT) (where pytpy = 4′-pyridyl-2,2′:6′,2″-terpyridyl). The individual oligomer chains comprised alternating Ru-PT and Os-PT units connected via Cu2+, Pd2+, Ag+, Fe2+, Co2+, or Zn2+ metallo-linkers. The growth and properties of the oligomer films were monitored in detail by UV–vis spectroscopy and cyclic voltammetry. The films exhibited a linear growth upon addition of the successive building blocks, with a joint grafting density of 3.9–5.0 × 1014 metallo-ligands/cm2 for the final oligomer films (10 layers), corresponding to a characteristic area of 2.0–2.5 nm2/oligomer. The only exception was the Pd2+-linked film on glass that showed an exponential growth, which, however, could also be changed to the linear mode by the introduction of a conductive substrate. The combination of two different functional molecular units in the oligomer chains resulted in enhancement of the optical window and in an increase in the number of the available redox states as compared to the analogous single component assemblies.
    The Journal of Physical Chemistry C 04/2014; 118(18):9578–9587. · 4.84 Impact Factor
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    ABSTRACT: While it is well-known that oligoethylene glycol (OEG) terminated self-assembled monolayers (SAMs) can be deteriorated by UV irradiation in air, we now report that the analogous modification can also be performed in water, opening the opportunity for in situ tuning of biorepulsive properties. Surprisingly, this deterioration also takes place even in the absence of molecular oxygen, resulting in a very selective process.
    Chemical Communications 03/2014; · 6.38 Impact Factor
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    ABSTRACT: Nanoscopic metal-molecule-metal junctions consisting of Fe-bis(terpyridine)-based ordered nanostructures grown in layer-by-layer fashion on a solid support are investigated by conductive atomic force microscopy, as described on page 1688 by P. Samorì, A. Licciardello, A. Troisi and co-workers. Hopping is demonstrated as the main charge-transport mechanism both experimentally and theoretically.
    Advanced Materials 03/2014; 26(11):1792. · 14.83 Impact Factor
  • Nikolaus Meyerbröker, Michael Zharnikov
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    ABSTRACT: Extremely elastic and highly stable nanomembranes of variable thickness (5-350 nm) made completely of poly(ethylene glycol) are prepared by a simple procedure. The membranes exhibit distinct biorepulsive and hydrogel properties. They offer new possibilities for applications such as supports in transmission electron microscopy, matrices for inorganic nanoparticles, and pressure-sensitive elements for sensors.
    Advanced Materials 02/2014; · 14.83 Impact Factor
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    M. Nuruzzaman Khan, Michael Zharnikov
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    M. Nuruzzaman Khan, Michael Zharnikov
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    M. Nuruzzaman Khan, Michael Zharnikov
  • M. Nuruzzaman Khan, Michael Zharnikov
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    ABSTRACT: Biorepulsive oligo(ethylene glycol) substituted alkanethiolate (OEG-AT) monolayers on gold can serve as primary templates for promoted (by electron irradiation) exchange reaction with thiolated ssDNA species, resulting in the formation of mixed OEG-AT/ssDNA monolayers of desired composition. Here we test the ability of alternative, disulfide precursors to serve as substituents in such a reaction. Two representative molecules, based on adenine-based homooligonucleotide (25-mer), were used, viz. asymmetric disulfide with a short second chain (A25SSOH) and symmetric disulfide (A25SSA25). The results were compared to the reference system of thiolated ssDNA (A25SH). Both disulfide precursors were found to be suitable for the reaction, further extending the types of commercially available compounds which can be used for this approach. A25SSOH exhibited quite high efficiency, similar to A25SH, while the efficiency of A25SSA25 was noticeably lower, especially at low irradiation doses (< 0.6 mC/cm2). Also, the single component, A25SSA25-based ssDNA monolayer was of lower quality as compared to the films prepared from the A25SH and A25SSOH precursors. The above observations were explained by the bulky character and conformational flexibility of A25SSA25, which hinders the proper assembly and efficient exchange reaction.
    The Journal of Physical Chemistry C 01/2014; · 4.84 Impact Factor
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    ABSTRACT: Nanoscopic metal–molecule–metal junctions consisting of Fe‐bis(terpyridine)‐based ordered nanostructures are grown in layer‐by‐layer fashion on a solid support. Hopping is demonstrated as the main charge‐transport mechanism both experimentally and theoretically.
    Advanced Materials 01/2014; 26(11). · 14.83 Impact Factor
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    Caitlin Howell, Hicham Hamoudi, Michael Zharnikov
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    ABSTRACT: Background The establishment of spectroscopic analysis techniques for complex, surface-bound biological systems is an important step toward the further application of these powerful experimental tools to new questions in biology and medicine. Methods We use a combination of the complementary spectroscopic techniques of X-ray photoelectron spectroscopy, Infrared reflection-absorption spectroscopy, and near-edge x-ray absorption fine structure spectroscopy to monitor the composition and molecular orientation in adenine/thymine diblock oligonucleotide films and their hybridized brushes on gold. Results We demonstrate that the surface-bound probe molecules, consisting of a binding adenine block, d(A), and a sensing thymine block, d(T), deviate from the ideal L-shape model due to the internal intra- and intermolecular hybridization. This effect becomes more pronounced with increasing length of the d(A) block. Nevertheless, these films were found to hybridize well with the complementary target d(A) strands, especially if they were treated in advance to reduce internal interaction between the molecules. In spite of the structural complexity of these films, the hybridization efficiency correlated well with the potential accessibility of the sensing d(T) blocks, defined by their lateral spacing. Conclusions These findings are a good demonstration of the strength of multi-technique spectroscopic analysis when applied to assemblies of biological molecules intrinsically prone to complex interactions.
    Biointerphases 12/2013; 8(1). · 1.91 Impact Factor
  • Hao Lu, Martin Kind, Andreas Terfort, Michael Zharnikov
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    ABSTRACT: A series of self-assembled monolayers (SAMs) of partially fluorinated alkanethiols (PFAT) with variable length of the fluorocarbon segment, viz. F(CF2)n(CH2)11SH (FnH11SH, n = 6, 8, and 10) were prepared on GaAs(001) and characterized by several complementary spectroscopic techniques. The SAMs were found to be well ordered and densely packed, and thus able to protect the substrate from oxidation, with the highest quality F10H11SH monolayer being most effective in this regard. The packing density of the SAMs was governed by the bulky fluorocarbon segments having a helical conformation. With decreasing length of these segments, a slight decrease in the packing density accompanied by progressive deterioration of the orientational order and a slight disturbance of the conformational order in the fluorocarbon part of the films occurred. In contrast, the hydrocarbon segments of the FnH11SH SAMs exhibited similar average orientation in all studied monolayers, accompanied by a partial conformational disorder. This was explained by the effect of a strong bending potential favoring a substrate–S–C angle of 104° and predefining, thus, the orientation of the hydrocarbon segments.
    The Journal of Physical Chemistry C 11/2013; 117(49):26166–26178. · 4.84 Impact Factor
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    ABSTRACT: Static charge transport (CT) properties of nitrile-substituted oligophenylenes and oligo(phenylene ethynylene)s (NC-OPh and NC-OPE, respectively) assembled via the thiolate anchor on gold substrates were measured by the mercury drop junction technique. The derived attenuation factors (β), viz. 0.53 ± 0.1 and 0.30 ± 0.08 Å–1 for the NC-OPh and NC-OPE monolayers, respectively, correlate well with the literature values for the analogous nonsubstituted systems, suggesting that the attachment of the nitrile group to the OPh or OPE backbone does not significantly affect their transport properties. This finding provides a basis for the use of the nitrile moiety as a resonantly addressable group and as specific charge injection site in the measurements of dynamic CT by resonant Auger electron spectroscopy. The comparison between the static and dynamic β values for the NC-OPh monolayers implies that the static value corresponds to nonresonant injection conditions. This suggests, potentially, that the static CT can be performed more efficiently by controlling the specific molecular orbitals into which charge carriers are injected.
    The Journal of Physical Chemistry C 11/2013; 117(48):25556–25561. · 4.84 Impact Factor
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    M. Nuruzzaman Khan, M. Zharnikov
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    ABSTRACT: Using a representative test system, we present here a versatile approach to prepare mixed monolayers of thiolated single-stranded DNA (ssDNA) and oligo(ethylene glycol) substituted alkanethiols (OEG-AT) in a broad range of compositions as well as ssDNA/OEG-AT patterns of desired shape imbedded into a biorepulsive background. The procedure involves two steps. First, a primary, well-defined OEG-AT monolayer on a solid support is exposed to UV light in either homogeneous or lithographic fashion. Second, the exchange reaction between the damaged OEG-AT species in the film and ssDNA substituents in solution occurs, resulting in formation of ssDNA/OEG-AT monolayer or pattern. The above procedure relies on commercially available compounds and does not require vacuum, which simplifies its application in research and industrial laboratories. The composition of the mixed films or ssDNA/OEG-AT spots (lithography) can be precisely adjusted by UV dose in an almost entire composition range. It was demonstrated that the procedure can be performed with UV light of different wavelengths (254 or 365 nm), which opens new possibilities for lithography. Using advanced spectroscopic tools, it was shown that ssDNA molecules imbedded into the OEG-AT matrix maintain their identity and intact character as well as exhibit predominant upright orientation typical of one-component films of thiolated ssDNA. The OEG-AT constituents of the mixed monolayers were found to be intact as well, with all UV damaged OEG-AT species being exchanged for ssDNA. Finally, a representative ssDNA/OEG-AT pattern was fabricated.
    The Journal of Physical Chemistry C 11/2013; 117(47):24883-24893. · 4.84 Impact Factor
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    ABSTRACT: Molecular assemblies of surface-confined heterometallic molecular dyads (SURHMDs) composed of optically rich and redox-active Fe(pytpy)2·2PF6 (Fe-PT), Ru(pytpy)2·2PF6 (Ru-PT) and Os(pytpy)2·2PF6 (Os-PT) pytpy = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridyl] complexes are fabricated via bottom-up approach on SiOx based solid supports. Pairing of the two different metal-organic complexes at a single platform results in significant enlargement of the optical window (λ = 400–800 nm), which can be of interest for potential applications. The use of the Cu-based linker ensures intramolecular electronic communication between these complexes. In addition, SURHMDs are electrochemically stable under large numbers of read-write cycles (103) and exhibit multiple redox states at relatively low potentials (<1.2 V). Moreover, an electrochemical input at controlled potentials creates a mixed-valence multicomponent system.
    Advanced Functional Materials 09/2013; 23(34). · 10.44 Impact Factor
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    ABSTRACT: As a holder of genetic information and due to its unique hybridization properties, deoxyribonucleic acid (DNA) represents a key object in modern science and related technology. Self assemble monolayer of single stranded DNA (ssDNA) on coinage metal such as gold can be employed for detection of DNA binding proteins and biosensor applications. A new two-step procedure is developed for fabrication of mixed monolayer of thiolated ssDNA and oligo(ethylene glycole) sub-stituted alkanethiolates (OEG-AT) OEG-AT, which are protein repelling in nature. This approach was combine with surface-initiated enzymatic polymerization (SIEP) for extension in the Z-direction and based on an irradiation-promoted exchange reaction (IPER). This approach allow us to program complex 3D pattern of DNA on surface by electron-beam lithography (EBL). The orientation and ordering of DNA in the one-component A25SH monolayer and mixed ssDNA/OEG-AT monolayers was investigated by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, which proved a significant control of upright orientation of the DNA strands in both systems. SAMs, homogeneous poly (A) brushes, and poly (A) nanostructures were characterized by laboratory and synchrotron-based PE spectroscopy, ellipsometry and atomic force microscopy (AFM). This system can be widely used as versatile functional moiety and nanoscale building block in such important fields as bio-engineering, bio-sensing, bio-nanotechnology, gene therapy, drug delivery, nanomedicine, and molecular biology
    19th International Vacuum Congress (IVC-19), International Conference on Nanoscience and Technology (ICN+T 2013, Palais des congrès" in Paris (France); 09/2013

Publication Stats

2k Citations
784.20 Total Impact Points

Institutions

  • 1999–2014
    • Universität Heidelberg
      • Institute of Physical Chemistry
      Heidelburg, Baden-Württemberg, Germany
  • 2013
    • Universität Basel
      • Department of Chemistry
      Basel, BS, Switzerland
  • 2012
    • University of Strasbourg
      Strasburg, Alsace, France
    • University of Delhi
      • Department of Chemistry (Faculty of Science)
      Delhi, NCT, India
  • 2011
    • Karlsruhe Institute of Technology
      • Institut für Toxikologie und Genetik
      Karlsruhe, Baden-Wuerttemberg, Germany
  • 2008–2010
    • Philipps University of Marburg
      • Faculty of Chemistry
      Marburg, Hesse, Germany
    • University of Wuerzburg
      • Division of Experimental Physics VII
      Würzburg, Bavaria, Germany
    • Jagiellonian University
      • Faculty of Physics, Astronomy and Applied Computer Science
      Cracovia, Lesser Poland Voivodeship, Poland
  • 2006–2010
    • Pennsylvania State University
      • Department of Chemistry
      University Park, Maryland, United States
  • 2009
    • University of Washington Seattle
      Seattle, Washington, United States
    • Paul Scherrer Institut
      Aargau, Switzerland
    • Yuanpei University
      Hsin-chu-hsien, Taiwan, Taiwan
  • 2008–2009
    • University of St Andrews
      Saint Andrews, Scotland, United Kingdom
  • 2007
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
    • Universität Regensburg
      • Institut für Analytische Chemie, Chemo- und Biosensorik
      Regensburg, Bavaria, Germany
  • 2004–2007
    • National Cheng Kung University
      • Department of Materials Science and Engineering
      Tainan, Taiwan, Taiwan
    • Heidelberg University
      Tiffin, Ohio, United States
  • 2005–2006
    • Hokkaido University
      • Graduate School of Science
      Sapporo-shi, Hokkaido, Japan
    • National Synchrotron Radiation Research Center (NSRRC)
      Hsin-chu-hsien, Taiwan, Taiwan
  • 1994–2004
    • Technische Universität München
      • • Walter Schottky Institut (WSI)
      • • Faculty of Physics
      München, Bavaria, Germany
  • 2002
    • Chung Yuan Christian University
      • Department of Biomedical Engineering
      Hsinchu, Taiwan, Taiwan