Horizontal versus vertical charge and energy transfer in hybrid assemblies of semiconductor nanoparticles

• Gilad Gotesman,
• Rahamim Guliamov and
• Ron Naaman

Beilstein J. Nanotechnol. 2012, 3, 629–636, doi:10.3762/bjnano.3.72

• . Experimental The NP assemblies were prepared as described previously [4]. Briefly, a monolayer of (3-mercaptopropyl)trimethoxysilane was self-assembled on quartz (Qz, fused silica) substrates. Next, a monolayer of core-only CdSe NPs (~6.3 nm diameter, emission peak at 641 nm) was attached to the thiol tail

• -octanedithiol (C8DT), and 1,10-decanedithiol (C10DT). Control experiments were performed with molecules of the same lengths but with only one thiol group. These molecules will be denoted as monothiols (MT, e.g., C6MT for 1-hexanethiol). To form the second layer of NPs, the samples were immersed in a solution of

• quenching was independent of the linker length. This effect is well known for CdSe NPs; it results from the formation of surface traps owing to the thiol binding [28][29][30][31]. The PL quenching, which is independent of the MT length, indicates that the number of traps is the same for all linkers, and

Mapping mechanical properties of organic thin films by force-modulation microscopy in aqueous media

• Jianming Zhang,
• Zehra Parlak,
• Carleen M. Bowers,
• Terrence Oas and
• Stefan Zauscher

Beilstein J. Nanotechnol. 2012, 3, 464–474, doi:10.3762/bjnano.3.53

• and contact forces, and (ii) in the unambiguous interpretation of the contrast in the amplitude images [38][39][40]. We demonstrate the capability of FMM to image mechanical properties in aqueous media on surface-tethered proteins and self-assembled EG3-thiol (triethylene glycol mono-11

• in aqueous solution. Future work to quantify these properties requires additional analytical models that capture the interaction of the cantilever beam with the liquid environment. FMM on patterned EG3-thiol monolayers The properties and applications of alkanethiol self-assembled monolayers (SAMs) on

• gold surfaces have been the subject of interface science research for many years. The self-assembly of alkane thiol molecules on gold surfaces is a two-step process. The initial physisorption step on gold substrates is typically slow and concentration-dependent [55]. Once in contact, the molecules

Colloidal lithography for fabricating patterned polymer-brush microstructures

• Tao Chen,
• Debby P. Chang,
• Rainer Jordan and
• Stefan Zauscher

Beilstein J. Nanotechnol. 2012, 3, 397–403, doi:10.3762/bjnano.3.46

• obtained by sputter deposition of the metal [2][4]. When gold is chosen as the metal, the ensuing pattern can be easily functionalized chemically with a self-assembled monolayer (SAM) of a thiol initiator, which can be subsequently amplified into polymer brushes. Figure 1 shows this strategy for the

• between the microspheres (Figure 1A). After the microsphere mask was removed by sonication, an array of hexagonally arranged triangular gold islands remained (Figure 1B) on which we formed a SAM of thiol initiator (BrC(CH3)2COO(CH2)11SH) [27]. We then synthesized poly(N-isopropylacrylamide) (PNIPAAM

• –surface contact area. This so-called edge-spreading lithography (ESL) employing colloid microspheres as templates has been previously used to fabricate ring-shaped metal patterns [9]. Here we replaced the octadecanethiol (ODT) molecules with thiol initiator (BrC(CH3)2COO(CH2)11SH), and amplified the

Functionalised zinc oxide nanowire gas sensors: Enhanced NO₂ gas sensor response by chemical modification of nanowire surfaces

• Eric R. Waclawik,
• Jin Chang,
• Andrea Ponzoni,
• Isabella Concina,
• Dario Zappa,
• Elisabetta Comini,
• Nunzio Motta,
• Guido Faglia and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2012, 3, 368–377, doi:10.3762/bjnano.3.43

• the thiol. The long DT hydrocarbon chains were expected to create a strongly hydrophobic surface. Similarly ZnO nanowire sensors were functionalised by tris(hydroxymethyl)aminomethane (THMA), and the response of THMA-functionalised sensors was compared to that of the unfunctionalised ZnO nanowire

• thiol (confirmed by FTIR) raised the conductivity of each individual sensor above the measurement range of our instrument (which corresponds to a minimum conductance value of Gmax = 10 mS). We conclude from this that chemisorption of the thiol significantly increased the density of electrons present in

Variations in the structure and reactivity of thioester functionalized self-assembled monolayers and their use for controlled surface modification

• Inbal Aped,
• Yacov Mazuz and
• Chaim N. Sukenik

Beilstein J. Nanotechnol. 2012, 3, 213–220, doi:10.3762/bjnano.3.24

• ]. The preparation of (S)-undec-10-enyl thioacetate from ω-undecenylbromide followed the previously published procedure [17]. ω-Undecenyl thiol was prepared by acid hydrolysis of the thioacetate, as follows: In a round-bottom flask (250 mL) equipped with a magnetic stirring bar and a reflux condenser

• (50 mL) and brine (50 mL). The hexane was dried over MgSO4 and filtered, and the solvent was removed on a rotovap. The crude ω-undecenyl thiol was purified by flash chromatography (hexane): Yield 6.02 g (82%); 1H NMR δ 1.20–1.47 (m, 13H), 1.61 (m, 2H), 2.04 (m, 2H), 2.52 (q, J = 7.5 Hz, 2H), 4.93 (m

• , 2H), 5.81 (ddt, J = 6.6, 10.2, 17 Hz, 1H); 13C NMR δ 24.80, 28.51, 29.06, 29.20, 29.24, 29.56, 29.59, 33.95, 34.19, 114.27, 139.36. The general procedure for the conversion of ω-undecenyl thiol into the thioester–olefin precursors for compounds 1b–i, 2, 3 and 4 is as follows: In a dry, round-bottom

Parallel- and serial-contact electrochemical metallization of monolayer nanopatterns: A versatile synthetic tool en route to bottom-up assembly of electric nanocircuits

• Jonathan Berson,
• Assaf Zeira,
• Rivka Maoz and
• Jacob Sagiv

Beilstein J. Nanotechnol. 2012, 3, 134–143, doi:10.3762/bjnano.3.14

• different from those usually produced in conventional electrochemical deposition on thiol/gold monolayers [36][37][38][39][40][41][42][43][44][45], which may occur in the monolayer-free regions of a destructively patterned monolayer [36][37][38][39][40][41][42], underneath the monolayer [41][42], or on top

Electron-beam patterned self-assembled monolayers as templates for Cu electrodeposition and lift-off

• Zhe She,
• Andrea DiFalco,
• Georg Hähner and
• Manfred Buck

Beilstein J. Nanotechnol. 2012, 3, 101–113, doi:10.3762/bjnano.3.11

• Zhe She Andrea DiFalco Georg Hahner Manfred Buck EaStCHEM School of Chemistry, University of St. Andrews, KY16 9ST, U.K School of Physics and Astronomy, University of St. Andrews, KY16 9ST, U.K 10.3762/bjnano.3.11 Abstract Self-assembled monolayers (SAMs) of 4'-methylbiphenyl-4-thiol (MBP0

• hexadecane thiol (CH3(CH2)15SH, MC16) as a blocking thiol [15]. The present paper is an investigation of a scheme for creating surface features with smaller dimensions by using e-beam patterning of a single-component SAM of ω-(4'-methylbiphenyl-4-yl)thiol (CH3–C6H4–C6H4–SH, MBP0). While selective deposition

• affecting the nucleation rate is specific to metals that bind more strongly to the thiol head group than the original substrate metal. In this case the metal deposited at defects can easily intercalate and diffuse at the SAM–substrate interface [48]. In the case of templated deposition by means of an e-beam

Substrate-mediated effects in photothermal patterning of alkanethiol self-assembled monolayers with microfocused continuous-wave lasers

• Anja Schröter,
• Mark Kalus and
• Nils Hartmann

Beilstein J. Nanotechnol. 2012, 3, 65–74, doi:10.3762/bjnano.3.8

• , thermal desorption of the thiol molecules is initiated [11]. Subsequently, the Au layer in these laser-depleted surface areas was removed by means of wet-chemical etching [11][29]. For this purpose, the patterned substrates were immersed into an aqueous solution of K2S2O3 and K3Fe(CN)6. The HDT SAM acts

• emitted power of a laser pointer. This opens up an opportunity for truly cost-effective laser processing of thiol-based SAMs. In addition, parallel processing, e.g., by using micromirror displays [34], appears feasible. The choice of the support material, of course, also affects the lateral resolution of

• . At a constant irradiation time, a certain temperature is required in order to induce substantial desorption of thiol molecules [21][22][37]. Following Equations 3–11 this necessitates a critical laser power density. Processing at short irradiation times demands high power densities, which may lead to

Transmission eigenvalue distributions in highly conductive molecular junctions

• Justin P. Bergfield,
• Joshua D. Barr and
• Charles A. Stafford

Beilstein J. Nanotechnol. 2012, 3, 40–51, doi:10.3762/bjnano.3.5

• ][12] to transport through SMJs utilized a semiempirical Hamiltonian [13] for the π-electrons, which accurately describes the gas-phase spectra of conjugated organic molecules. Although this approach should be adequate to describe molecules weakly coupled to metal electrodes, e.g., by thiol linkages

• the rank of Γα is equal to the number of covalent bonds formed between the two. For example, in a SMJ where a Au electrode bonds to an organic molecule through a thiol group, only a single bond is formed, and there is only one significant transmission channel [15][16]. In Pt–benzene–Pt junctions

X-ray spectroscopy characterization of self-assembled monolayers of nitrile-substituted oligo(phenylene ethynylene)s with variable chain length

• Hicham Hamoudi,
• Ping Kao,
• Alexei Nefedov,
• David L. Allara and
• Michael Zharnikov

Beilstein J. Nanotechnol. 2012, 3, 12–24, doi:10.3762/bjnano.3.2

• were combined with a suitable anchor (head) group having a strong affinity to the selected substrate. The most frequently used group in this regard is thiol, which allows SAM-like assembly of the molecules on coinage metal and various semiconductor substrates, for example Au and GaAs, respectively

• spectra is shown in detail in Figure 4, along with the spectra of the two reference systems, viz. SAMs of nitrile-substituted biphenylthiol (NC-BPT) [30] and 1,1′;4′,1″-terphenyl-4-thiol (TPT) [42][43] on Au. The spectra of the target films are dominated by a strong peak, consisting of at least three

• integrity of the SAMs, infrared spectra were obtained. In all cases the SAMs had the expected spectra based on reference spectra of the pure thiol molecules used for self-assembly. A schematic drawing of the target molecules along with their acronyms. S 2p (a), C 1s (b), and N 1s (c) HRXPS spectra of the

Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94

• dioxide was grown from a solution containing titanium sulfate and hydrogen peroxide [34]. Obtaining SAMs with sulfonate outer groups is not trivial. It is usually done either by reacting chemisorbed SAMs having a thioacetate terminal group [33] or by reacting terminating thiol groups with H2O2 in acetic

• ) heterojunction nanowires by a “bottom-up” approach [96]. Here, Au–TiO2–Au nanowires were prepared within nanoholes of anodic aluminum oxide templates. The preparation procedure included the deposition of gold by electroplating, chemisorption of 1,8-octanedithiol (HS–(CH2)8–SH), oxidation of the terminal thiol

Direct monitoring of opto-mechanical switching of self-assembled monolayer films containing the azobenzene group

• Einat Tirosh,
• Enrico Benassi,
• Silvio Pipolo,
• Marcel Mayor,
• Michal Valášek,
• Veronica Frydman,
• Stefano Corni and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2011, 2, 834–844, doi:10.3762/bjnano.2.93

• atomic force microscopy (AFM) and atomistic computational study of the change in local stiffness, as induced by the optical cis↔trans conversion in a SAM of 4'-{[(1,1'-biphenyl)-4-yl]diazenyl}-(1,1'-biphenyl)-4-thiol (thio-2-DA). The experimental variation in stiffness shows quantitative agreement with

• Experimental methods Preparation of 4'-{[(1,1'-biphenyl)-4-yl]diazenyl}-(1,1'-biphenyl)-4-thiol (2, thio-2-DA) Initial attempts to prepare monolayers directly from compound 1 as reported previously [23][24] were unsuccessful. Therefore, a reduction was carried out as indicated in Figure 7, and outlined below

• and the mixture was sealed and stirred at room temperature for 4 h. The solvents were then evaporated under reduced pressure affording the thiol 2, thio-2-DA, which was used without further purification; 1H NMR (CDCl3) δ 3.5 (s, –SH), 7.4 (d, 3H), 7.5 (t, 2H), 7.6 (d, 2H), 7.7–7.8 (m, 6H), 8.0 (m, 4H

Mechanical characterization of carbon nanomembranes from self-assembled monolayers

• Xianghui Zhang,
• André Beyer and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2011, 2, 826–833, doi:10.3762/bjnano.2.92

• terminal and/or anchor groups were used to prepare the CNMs, such as 4'-[(3-trimethoxysilyl)propoxy]-[1,1'-biphenyl]-4-carbonitrile (CBPS), 1,1'-biphenyl-4-thiol (BPT) and 4-nitro-1,1'-biphenyl-4-thiol (NBPT). The elastic properties, viscoelastic behaviors and ultimate tensile strength of these biphenyl

• case of biphenylthiol CNMs, chemical bonds between the CNM and silicon are unlikely, as intermolecular disulfide bonds form immediately after the cleavage of the thiol-CNM from its original gold substrate. Because flexible CNMs may even conform to surfaces with a nanoscale roughness, the adhesion

• biphenyl molecules were used to fabricate CNMs. SAMs of 4'-[(3-trimethoxysilyl)propoxy]-[1,1'-biphenyl]-4-carbonitrile (CBPS) were formed on silicon nitride, SAMs of 4'-nitro-1,1'-biphenyl-4-thiol (NBPT) and 1,1'-biphenyl-4-thiol (BPT) on gold surfaces. The thickness of the respective SAMs was determined

Towards quantitative accuracy in first-principles transport calculations: The GW method applied to alkane/gold junctions

• Mikkel Strange and
• Kristian S. Thygesen

Beilstein J. Nanotechnol. 2011, 2, 746–754, doi:10.3762/bjnano.2.82

• structure of the molecule as well as the detailed atomic structure of the metal–molecule contact. Variations in the contact geometry beyond experimental control lead to an undesired spread in the measured conductance properties. For the most commonly used anchoring group, –thiol, these effects are rather

• investigated experimentally [1][12][33][34][35][36][37][38][39][40][41][42][43][44]. We focus here on the amine-linked alkanes to avoid the uncertainties related to the gold–thiol contact geometry, which is presently under debate [45][46][47][48][49][50]. We note that very recently it was shown that alkanes

Charge transport in a zinc–porphyrin single-molecule junction

• Mickael L. Perrin,
• Christian A. Martin,
• Ferry Prins,
• Ahson J. Shaikh,
• Rienk Eelkema,
• Jan H. van Esch,
• Jan M. van Ruitenbeek,
• Herre S. J. van der Zant and
• Diana Dulić

Beilstein J. Nanotechnol. 2011, 2, 714–719, doi:10.3762/bjnano.2.77

• complex of zinc(II) 5,15-di(p-thiolphenyl)-10,20-di(p-tolyl)porphyrin and pyridine (ZnTPPdT–Pyr) (see Figure 1a for the structural formula) was dissolved in dichloromethane (DCM) and deposited on the unbroken electrodes by means of self-assembly from solution. Two thiol groups on opposite sides of the

An MCBJ case study: The influence of π-conjugation on the single-molecule conductance at a solid/liquid interface

• Wenjing Hong,
• Hennie Valkenier,
• Gábor Mészáros,
• David Zsolt Manrique,
• Artem Mishchenko,
• Alexander Putz,
• Pavel Moreno García,
• Colin J. Lambert,
• Jan C. Hummelen and
• Thomas Wandlowski

Beilstein J. Nanotechnol. 2011, 2, 699–713, doi:10.3762/bjnano.2.76

• ), which leads to the most probable conductance value of 10−4.5 G0 for a single gold|AC|gold junction. Further pulling causes an elongation of the Au–thiol bond until the junction breaks. The low-conductance feature is attributed to the formation of molecular stacks after breaking of the gold leads [44][62

The atomic force microscope as a mechano–electrochemical pen

• Christian Obermair,
• Andreas Wagner and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2011, 2, 659–664, doi:10.3762/bjnano.2.70

• passivation layer. This passivation layer consists of oxo-anions of the electrolyte, such as sulphate or hydrogen sulfate, which are well known from literature to cover metal films in their presence [29][30][31][32][33]. Alternatively, thiol molecules were used in our experiments as an organic passivation

• layer. These thiol molecules have a higher adhesion to the substrate but are not necessary for a precise deposition and are therefore not discussed in any more detail below. While an electrochemical potential appropriate for tip-induced electrochemical deposition is applied to the gold electrode

Fabrication of multi-parametric platforms based on nanocone arrays for determination of cellular response

• Lindarti Purwaningsih,
• Tobias Schoen,
• Tobias Wolfram,
• Claudia Pacholski and
• Joachim P. Spatz

Beilstein J. Nanotechnol. 2011, 2, 545–551, doi:10.3762/bjnano.2.58

• substrates through a thiol linker system. Improved neural cell adhesion can be obtained and is dependent on the nature of the nanocone surface, thus illustrating the influence of different surface topographies on the nanometer length scale, on a complex cellular behavior such as cell adhesion. Substrate and

• on large areas. Gold nanoparticles on top of the nanostructures allow for spatially resolved functionalization with a variety of biomolecules through simple thiol chemistry. A 3,3'-dithiobis(sulfosuccinimidylpropionate) (DTSSP) linker molecule was used to immobilize laminin, an extracellular matrix

• human neuroblastoma cells. Figure 2 shows adhered SHSY5Y human neuroblastoma cells on top of the nanostructured arrays. The gold-tipped nanocones were biofunctionalized with laminin with DTSSP as a thiol-based linker between the gold tips and the protein. Laminin is a protein that mediates cell adhesion

Tip-enhanced Raman spectroscopic imaging of patterned thiol monolayers

• Johannes Stadler,
• Thomas Schmid,
• Lothar Opilik,
• Phillip Kuhn,
• Petra S. Dittrich and
• Renato Zenobi

Beilstein J. Nanotechnol. 2011, 2, 509–515, doi:10.3762/bjnano.2.55

• analyte in a short time, allowing acquisition of Raman images of a surface area covered with weakly scattering molecules. The information from such a Raman image was used here to chemically identify and localize two different thiol isomers in an inhomogeneous self-assembled monolayer (SAM). In this work

• surfaces or certain surface areas. Here, selected areas on a gold surface were modified by a thiol and, in a second step, the remaining substrate was covered by a secondary thiol film. This type of surface can act as a basis for biosensors [12][13]. To produce patterned SAM structures on a gold surface

• considerable Raman intensity changes, thus flat gold films are an ideal substrate to minimize the STM feedback changes and distance related artifacts. Previous studies on self-assembled thiol films were conducted using AFM [13], STM [15][24][25], XPS and Ellipsometry [26] as well as Raman spectroscopy [27][28

Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle–substrate chemistry and morphology, and of operating conditions

• Samer Darwich,
• Karine Mougin,
• Akshata Rao,
• Enrico Gnecco,
• Shrisudersan Jayaraman and
• Hamidou Haidara

Beilstein J. Nanotechnol. 2011, 2, 85–98, doi:10.3762/bjnano.2.10

• coated with methyl (–CH3) and hydroxyl (–OH) terminated thiol groups. This major result suggests that the adhesion of the particles to the substrate is strongly reduced by the presence of hydrophobic interfaces. The influence of critical parameters on the manipulation was investigated and discussed viz

• illustrated in Figure 5a. This series of experiments was performed on a Veeco AFM whose tip follows a zigzag scan path. The role of the hydrophobic or hydrophilic character of the interface in the manipulation process was investigated, using gold nanoparticles bearing OH- and CH3-terminated thiol groups (as

• methyl-thiol-stabilized gold nanoparticles were synthesized according to a modified version of two common syntheses [21]. The as-synthesized nanosphere solution [27][28] was centrifuged at 7000 rpm for 20 min to pellet the nanoparticles, decanted, and then re-suspended in 1 mL of deionized water to

Magnetic nanoparticles for biomedical NMR-based diagnostics

• Huilin Shao,
• Tae-Jong Yoon,
• Monty Liong,
• Ralph Weissleder and
• Hakho Lee

Beilstein J. Nanotechnol. 2010, 1, 142–154, doi:10.3762/bjnano.1.17

• epichlorohydrin and activated by ammonia to provide primary amine group functionality. The amine groups can then be easily reacted with various agents containing anhydride, hydroxyl, carboxyl, thiol, or epoxide groups, to confer molecular specificity to the nanoparticle through bioconjugation [43]. Amine

• . This sequence served as a linker, binding both an avidin-conjugated CLIO population (via the biotin/avidin interaction) as well as a second CLIO population (via the thiol provided by the terminal cysteine on the peptide) [13]. The subsequent addition of caspase-3 disassembled the aggregates by cleaving

Sensing surface PEGylation with microcantilevers

• Natalija Backmann,
• Natascha Kappeler,
• Thomas Braun,
• François Huber,
• Hans-Peter Lang,
• Christoph Gerber and
• Roderick Y. H. Lim

Beilstein J. Nanotechnol. 2010, 1, 3–13, doi:10.3762/bjnano.1.2

• surface PEGylation, and (2) conformational changes in the PEG layer over a timescale of tens of minutes in situ. Specifically, thiol-terminated PEG (mPEG–SH, 20 kDa) chains have been covalently tethered onto Au-coated microcantilever surfaces by the “grafting to” approach. When switching between good

• (polyethylene glycol) thiol 20000 (mPEG–SH, MW ~ 20000) was purchased from Laysan Bio Inc (Arab, AL). (1-Mercapto-11-undecyl)tetra(ethylene glycol) (EG4–C11–SH, MW ~ 380.5) was obtained from Asemblon Inc (Seattle, WA), diluted in ethanol to an end concentration of 10 mM and stored at +4 °C. Coating of