The use of XPS to examine the interaction of poly(acrylic acid) with oxidised metal substrates

Leadley, Stuart R.; Watts, John F.

doi:10.1016/s0368-2048(97)00028-5

Cited by 75 publications

(74 citation statements)

References 14 publications

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“…31,32 The presence of these structure and functional group agrees well with the expected surface structure of PAA-GO. Furthermore, x-ray photon spectroscopy results of PAA-GO show that the PAA main chain structure and the -COOH functional group have a 1:1 peak ratio, providing clear evidence that GO has been successfully grafted with PAA.…”

Section: Dovepresssupporting

confidence: 78%

Improving thermal stability and efficacy of BCNU in treating glioma cells using PAA-functionalized graphene oxide

Yang²,

Hung³

et al. 2012

IJN

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Background: 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), a commercial chemotherapeutic drug for treating malignant brain tumors, has poor thermal stability and a short half-life. Immobilization of BCNU on a nanocarrier might increase the thermal stability of BCNU and extend its half-life. Methods: Nanosized graphene oxide (GO) could be modified by polyacrylic acid (PAA) to improve the aqueous solubility and increase the cell penetration efficacy of the nanocarrier. PAA-GO intended as a drug carrier for BCNU was prepared and characterized in this study. The size and thickness of PAA-GO was investigated by transmission electron microscopy and atomic force microscopy, and the presence of PAA functional groups was confirmed by electron spectroscopy for chemical analysis and thermogravimetric analysis. BCNU was conjugated to PAA-GO by covalent binding for specific killing of cancer cells, which could also enhance the thermal stability of the drug. Results: Single layer PAA-GO (about 1.9 nm) with a lateral width as small as 36 nm was successfully prepared. The optimum drug immobilization condition was by reacting 0.5 mg PAA-GO with 0.4 mg BCNU, and the drug-loading capacity and residual drug activity were 198 µg BCNU/mg PAA-GO and 70%, respectively. This nanocarrier significantly prolonged the half-life of bound BCNU from 19 to 43 hours compared with free drug and showed efficient intracellular uptake by GL261 cancer cells. The in vitro anticancer efficacy of PAA-GO-BCNU was demonstrated by a 30% increase in DNA interstrand cross-linking and a 77% decrease in the IC 50 value toward GL261 compared with the same dosage of free drug. Conclusion: Nanosized PAA-GO serves as an efficient BCNU nanocarrier by covalent binding. This nanocarrier will be a promising new vehicle for an advanced drug delivery system in cancer therapy.

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Section: Dovepresssupporting

confidence: 78%

Improving thermal stability and efficacy of BCNU in treating glioma cells using PAA-functionalized graphene oxide

Yang²,

Hung³

et al. 2012

IJN

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“…and 288.0 eV, assigned respectively to adventitious carbon, residual methoxide groups from the catalyst precursor, and carbonate groups. [81][82][83][84] The proportion of surface methoxide increased monotonically relative to the as calcined NanoMgO-700, even after exposure to low methanol doses (Fig. 3b).…”

Section: Scheme 3: Dissociation Of H2o Over Mg 2+ -O 2-dimersmentioning

confidence: 92%

“…An alternative decomposition pathway could occur via surface -OH catalysed hydrolysis of adsorbed esters to generate surface acetate groups. [34] However, spectral contributions from such acetate groups would likely overlap with the C 1s state observed at 294 eV over nanoMgO-700, [76,84] originating from surface carbonate, [66,83] and hence cannot be unequivocally revoked. Scheme 5: DFT optimized structures of the ester molecule adsorbed on a MgO(100) step, before and after methyl group deprotonation.…”

Section: Nanomgo-700 O 1smentioning

confidence: 99%

The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

et al. 2016

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An in situ XPS study of water, methanol and methyl acetate adsorption over as-synthesised and calcined MgO nanocatalysts is reported with a view to gaining insight into the surface adsorption of key components relevant to fatty acid methyl esters (biodiesel) production during the transesterification of triglycerides with methanol. High temperature calcined NanoMgO-700 adsorbed all three species more readily than the parent material due to the higher density of electron-rich (111) and (110) facets exposed over the larger crystallites. Water and methanol chemisorb over the NanoMgO-700 through the conversion of surface O 2-sites to OH -and coincident creation of Mg-OH or Mg-OCH3 moieties respectively. A model is proposed in which the dissociative chemisorption of methanol occurs preferentially over defect and edge sites of NanoMgO-700, with higher methanol coverages resulting in physisorption over weakly basic (100) facets. Methyl acetate undergoes more complex surface chemistry over NanoMgO-700, with C-H dissociation and ester cleavage forming surface hydroxyl and acetate species even at extremely low coverages, indicative of preferential adsorption at defects.Comparison of C 1s spectra with spent catalysts from tributyrin transesterification suggest that ester hydrolysis plays a key factor in the deactivation of MgO catalysts for biodiesel production.

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“…This could be explained by the increasing total density of the sample. The C 1s XPS peak could be decomposed into 4 components if the carboxylic acid chain length was 3 or 6 (284.8 eV for C-C, 286.2 eV for C-O, 288.3 eV for O-C-O or C¼ O and 288.9 eV for the O¼ C-O bonded carbon), whereas in the case of longer aliphatic chains the C 3 peak was not detectable [237].…”

Section: Covalent Functionalization Of Titanate Nanostructuresmentioning

confidence: 99%

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

Kukovecz

Kordás

Kiss

2016

Surface Science Reports

104

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Titanates are salts of polytitanic acid that can be synthesized as nanostructures in a great variety concerning crystallinity, morphology, size, metal content and surface chemistry.Titanate nanotubes (open-ended hollow cylinders measuring up to 200 nm in length and 15 nm in outer diameter) and nanowires (solid, elongated rectangular blocks with length up to 1500 nm and 30-60 nm diameter) are the most widespread representatives of the titanate nanomaterial family. This review covers the properties and applications of these two materials from the surface science point of view. Dielectric, vibrational, electron and X-ray spectroscopic results are comprehensively discussed first, then surface modification methods including covalent functionalization, ion exchange and metal loading are covered. The versatile surface chemistry of onedimensional titanates renders them excellent candidates for heterogeneous catalytic, photocatalytic, photovoltaic and energy storage applications, therefore, these fields are also reviewed.

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The use of XPS to examine the interaction of poly(acrylic acid) with oxidised metal substrates

Cited by 75 publications

References 14 publications

Improving thermal stability and efficacy of BCNU in treating glioma cells using PAA-functionalized graphene oxide

Improving thermal stability and efficacy of BCNU in treating glioma cells using PAA-functionalized graphene oxide

The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

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