Nanoscale Biomolecular Structures on Self‐Assembled Monolayers Generated from Modular Pegylated Disulfides

Wong, Lu Shin; Janusz, Stefan; Sun, Shuqing; Leggett, Graham J.; Micklefield, Jason

doi:10.1002/chem.200902439

Cited by 13 publications

(7 citation statements)

References 62 publications

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“…Heating this ordered overlayer can cause the individual strands of the formate to interact with each other on bending. The terminal H atoms can react with other terminal H atoms to form H 2 as has been observed in the study of self assembled monolayers [9][10][11]. We have observed coincident H 2 and CO 2 evolution at 440 K from an overlayer of formate species at 80 % of saturation [12], suggesting that the self assembled monolayer mechanism could operate under these conditions.…”

Section: Introductionsupporting

confidence: 72%

Postulate of a Mechanism for Temperature Programmed Reaction Spectroscopy (TPRS) Which Accounts for the Coincident Evolution of H2 and CO2 in the TPRS of Succinates and Formates Adsorbed on Cu: Description of a Novel Method for the Identification of the Surface Morphology of Cu on Supported Cu Catalysts

Waugh

2015

Catal Lett

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The combination of temperature programmed reaction spectroscopy, temperature programmed oxidation (TPO) and N 2 O reactive frontal chromatography (N 2 O-RFC) has shown that the adsorbate produced by dosing dimethylsuccinate on to a Cu/Al 2 O 3 catalyst is a succinate species with 8 out of 10 surface Cu atoms having a succinate species adsorbed on them. The succinate species are bonded end-on and unidentate to the Cu atoms. This configuration constitutes a self-assembled monolayer. Temperature programming causes vicinal strands of the adsorbed succinate to interact, resulting in simultaneous dehydrogenation and decarboxylation, producing coincident evolution of H 2 and CO 2 in peaks at 668 and 793 K and leaving the C of the succinate chain on the Cu surface This C is removed by TPO, producing CO 2 at a peak maximum temperature of 593 K. Prior to the oxidation of the C to CO 2 , TPO oxidises the Cu metal to CuO in the temperature range 323-493 K. Reduction of this CuO produces Cu metal whose metal surface area as measured by N 2 O-RFC is 9.8 m 2 g -1 , a value which is identical to that of the fresh Cu/Al 2 O 3 catalyst. Therefore oxidation of the Cu metal to bulk CuO and re-reduction does not cause sintering of the Cu. However, the surface morphology of the Cu metal produced by reduction of the CuO has changed as evidenced by temperature programmed reduction (TPR)

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Section: Introductionsupporting

confidence: 72%

Postulate of a Mechanism for Temperature Programmed Reaction Spectroscopy (TPRS) Which Accounts for the Coincident Evolution of H2 and CO2 in the TPRS of Succinates and Formates Adsorbed on Cu: Description of a Novel Method for the Identification of the Surface Morphology of Cu on Supported Cu Catalysts

Waugh

2015

Catal Lett

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“…The peaks at ∼2880 cm À1 are consistent with the symmetric stretching of alkyl CÀH bonds in the polyethylene glycol chains, compared with the ATR-IR spectrum of the azido-PEG-COOH reagent and the IR data in the literature. 53 These absorption peaks indicate that the polyethylene glycol chains with carboxyl end-groups were successfully grafted on the SPgraphene flakes. As a control, the click reaction was also carried out on 4-propargyloxyphenyl functionalized SP-graphene without adding CuSO 4 .…”

Section: ' Results and Discussionmentioning

confidence: 98%

Click Chemistry on Solution-Dispersed Graphene and Monolayer CVD Graphene

et al. 2011

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Graphene from two different preparative routes was successfully functionalized with 4-propargyloxybenzenediazonium tetrafluoroborate in order to study a subsequent attachment by click chemistry (1,3-dipolar azideÀalkyne cycloaddition) of a short chain polyethylene glycol with terminal carboxylic end group (PEG-COOH). The reaction steps were studied by FTIR and Raman spectroscopies, as well as zeta-potential and surface tension measurements. In the first route, pristine graphene was surfactant dispersed from a stage controlled expanded graphite before reaction, resulting in colloidally stable dispersions after dialysis removal of the surfactant following the two functionalization steps. The chemistry was shown to increase the zeta-potential from À45.3 to À54.6 mV and increase the surface tension from 48.5 to 63.0 mN/m compared to those of the precursor solution. The magnitudes of the zeta-potential and the resulting solution concentration were shown to increase with grafting density up to 14.2 μg/mL. A colloidal stability model was used to estimate the maximum grafting density of the PEG-COOH groups yielding a value of 1 per 10 nm 2 . Raman mapping before and after the two-step functionalization suggests that edges and defects are preferentially reacted. In the second route, we investigated the same click chemistry functionalization on chemical vapor deposition (CVD) synthesized monolayer graphene films, which showed higher reactivity than solution-dispersed graphene. Because these methods do not originate with the more oxidized forms of graphene, the results point to new ways of more precisely controlling the chemistry of graphene.

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“…Nanostructured surfaces can be fabricated using various approaches, such as lithographic methods [9], [10], self-assembly processes [10], [11], treatment of polymers using plasma, ultraviolet light or ion irradiation [12], [13], etching of polymers using acids or hydroxides [6], creation of nanofibrous membranes using an electrospinning technique [14], and immobilization of biomolecules, such as extracelular matrix (ECM) molecules [15] or synthetic ECM-derived oligopeptidic ligands for cell adhesion receptors [16], on the material surface. Another important technique for creating nanostructured surfaces is deposition of nanoparticles on the material surface.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Growth and Osteogenic Differentiation of Human Osteoblast-Like Cells on Boron-Doped Nanocrystalline Diamond Thin Films

et al. 2011

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Intrinsic nanocrystalline diamond (NCD) films have been proven to be promising substrates for the adhesion, growth and osteogenic differentiation of bone-derived cells. To understand the role of various degrees of doping (semiconducting to metallic-like), the NCD films were deposited on silicon substrates by a microwave plasma-enhanced CVD process and their boron doping was achieved by adding trimethylboron to the CH4:H2 gas mixture, the B∶C ratio was 133, 1000 and 6700 ppm. The room temperature electrical resistivity of the films decreased from >10 MΩ (undoped films) to 55 kΩ, 0.6 kΩ, and 0.3 kΩ (doped films with 133, 1000 and 6700 ppm of B, respectively). The increase in the number of human osteoblast-like MG 63 cells in 7-day-old cultures on NCD films was most apparent on the NCD films doped with 133 and 1000 ppm of B (153,000±14,000 and 152,000±10,000 cells/cm2, respectively, compared to 113,000±10,000 cells/cm2 on undoped NCD films). As measured by ELISA per mg of total protein, the cells on NCD with 133 and 1000 ppm of B also contained the highest concentrations of collagen I and alkaline phosphatase, respectively. On the NCD films with 6700 ppm of B, the cells contained the highest concentration of focal adhesion protein vinculin, and the highest amount of collagen I was adsorbed. The concentration of osteocalcin also increased with increasing level of B doping. The cell viability on all tested NCD films was almost 100%. Measurements of the concentration of ICAM-1, i.e. an immunoglobuline adhesion molecule binding inflammatory cells, suggested that the cells on the NCD films did not undergo significant immune activation. Thus, the potential of NCD films for bone tissue regeneration can be further enhanced and tailored by B doping and that B doping up to metallic-like levels is not detrimental for cells.

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Nanoscale Biomolecular Structures on Self‐Assembled Monolayers Generated from Modular Pegylated Disulfides

Cited by 13 publications

References 62 publications

Click Chemistry on Solution-Dispersed Graphene and Monolayer CVD Graphene

Enhanced Growth and Osteogenic Differentiation of Human Osteoblast-Like Cells on Boron-Doped Nanocrystalline Diamond Thin Films

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