Structure and binding of alkanethiolates on gold and silver surfaces: implications for self-assembled monolayers

Sellers, Harrell; Ulman, Abraham; Shnidman, Yitzhak; Eilers, James E.

doi:10.1021/ja00074a004

Cited by 948 publications

(1,022 citation statements)

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“…Two theoretical studies have concluded that the adsorption site for a single thiol molecule on the gold (111) surface is the hcp hollow site. 30,31 These results also support the standard model. However, despite the overall agreement of the results, there are discrepancies regarding the S-Au distance and the tilt of the molecule in these two independent studies.…”

supporting

confidence: 82%

“…Alkanethiolates occupy three-fold hollow sites of the Au (111) surface with S-S spacings of 4.99Å, and the molecular axes are tilted by 30 • -35 • with respect to the surface normal. [13][14][15][16][17][18][19][20][21][22][23][30][31][32][33][34][35] The sulfur-pairing model involves a c(4 × 2) superlattice of the hexagonal lattice, where alkanethiolates form sulfur head group dimers with S-S spacings of 2.2Å. [9][10][11][12][24][25][26] Furthermore, other structural models have been reported, including n × √ 3 unit cells (8 ≤ n ≤ 10).…”

mentioning

confidence: 99%

“…The dashed curve is for the orientation used in Ref. 30 and the solid line is the minimum-energy path. Our results show that the staggered configuration is preferred over the configuration used in previous studies.…”

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confidence: 99%

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n-alkyl thiol head-group interactions with the Au(111) surface

2001

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State-of-the-art first principles calculations based on density functional theory were performed on CH 3 (CH 2 ) n−1 S-Au(111) systems. We show that the adsorption site of methylthiolate at low coverage on the Au(111) surface is the fcc site, not the hcp site as has been recently reported. Further, we report results for chain length dependency and the electronic structure of the system.The interaction between organic materials and solid surfaces has been extensively studied because of the broad range of industrial applications. 1-4 Self-assembled monolayers (SAMs) hold special interest, because the presence of the thiol group greatly strengthens the molecule-surface interactions, inducing order in the layer. SAMs have important potential applications in industry, such as sensors, transducers, detectors, packaging and insulating layers for integrated circuits, functionalization of surfaces, thin coatings for electrodes, and corrosion inhibition.The long-chain alkane thiols [CH 3 (CH 2 ) n−1 SH, or C n ] form SAMs on the Au(111) surface. Their simplicity, highly ordered structures, and chemical stability make these systems ideal for study with a variety of techniques including atomic force microscopy, 5,6 infrared spectroscopy, 7,8 high-resolution electron-energy-loss spectroscopy, 9 grazing X-ray diffraction, 10 scanning tunneling microscopy (STM), 11-17 scanning probe microscopy, 18 lowenergy electron diffraction (LEED), [19][20][21] He atom diffraction, 22,23 and theory. 25-31 Despite 1

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confidence: 82%

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confidence: 99%

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n-alkyl thiol head-group interactions with the Au(111) surface

2001

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“…This could be mainly because DNA-AgNPs are less stable than DNA-AuNPs. Thiol-AgNP interaction can be much more easily broken than thiol-AuNP complex because the binding energy of thiol-Ag is weaker than that of thiol-Au 22 . AgNP is chemically less stable and induces the cytotoxicity through mitochondrial dysfunction, induction of reactive oxygen species and DNA damage 23 while the cytotoxicity of AuNPs, compared with AgNPs, is negligible 24,25 .…”

Section: Resultsmentioning

confidence: 99%

Bio-barcode gel assay for microRNA

2014

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MicroRNA has been identified as a potential biomarker because expression level of microRNA is correlated with various cancers. Its detection at low concentrations would be highly beneficial for cancer diagnosis. Here, we develop a new type of a DNA-modified gold nanoparticle-based bio-barcode assay that uses a conventional gel electrophoresis platform and potassium cyanide chemistry and show this assay can detect microRNA at aM levels without enzymatic amplification. It is also shown that single-base-mismatched microRNA can be differentiated from perfectly matched microRNA and the multiplexed detection of various combinations of microRNA sequences is possible with this approach. Finally, differently expressed microRNA levels are selectively detected from cancer cells using the bio-barcode gel assay, and the results are compared with conventional polymerase chain reaction-based results. The method and results shown herein pave the way for practical use of a conventional gel electrophoresis for detecting biomolecules of interest even at aM level without polymerase chain reaction amplification.

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“…0.9 µM, which corresponds to 131 molecules per NPs and a 39% of surface coverage. Assuming that the remaining 61% is covered by MUA, and taking into account that the footprint for alkanethiols on gold is reported to be 0.21 nm 2 [34], the number of MUA per NP would be ca. 1945, which is 15 times higher than the amount of SH-PEG.…”

Section: Resultsmentioning

confidence: 99%

The role of PEG conformation in mixed layers: from protein corona substrate to steric stabilization avoiding protein adsorption

Comenge¹

2015

ScienceOpen Research

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Although nanoparticles (NPs) have been traditionally modified with a single ligand layer, mixture of ligands might help to combine different functionalities and to further engineer the NP surface. A detailed study of the competition between an alkanethiol (11-mercaptoundecanoic acid) and SH-PEG for the surface of AuNPs and the resultant behaviors of this model nanoconjugate is presented here. As a result, the physicochemical properties of these conjugates can be progressively tuned by controlling the composition and especially the conformation of the mixed monolayer. This has implications in the physiological stability. The controlled changes on the SH-PEG conformation rather than its concentration induce a change in the stabilization mechanism from electrostatic repulsion to steric hindrance, which changes the biological fate of NPs. Importantly, the adsorption of proteins on the conjugates can be tailored by tuning the composition and conformation of the mixed layer.

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Structure and binding of alkanethiolates on gold and silver surfaces: implications for self-assembled monolayers

Cited by 948 publications

References 2 publications

n-alkyl thiol head-group interactions with the Au(111) surface

n-alkyl thiol head-group interactions with the Au(111) surface

Bio-barcode gel assay for microRNA

The role of PEG conformation in mixed layers: from protein corona substrate to steric stabilization avoiding protein adsorption

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