Detection of Free Base Surface Enrichment of a Pharmaceutical Salt by X-ray Photoelectron Spectroscopy (XPS)

Stevens, Joanna S.; Byard, Stephen J.; Zlotnikov, Evgeny; Schroeder, Sven L. M.

doi:10.1002/jps.22334

Cited by 13 publications

(12 citation statements)

References 11 publications

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“…4, Table II) arose from the CSC linkage between PCL‐CEA and the cysteine residue of RGDSC, while the absence of a chlorine signal indicated no unreacted CEA residues on PCL within the sensitivity of detection (0.1 atomic %, 1ppth). Increased intensity was also observed for amide‐specific binding energies in the C1s and O1s spectra compared with PCL, along with the presence of CN and COO − from the peptide 23. This was particularly noticeable for oxygen (Fig.…”

Section: Resultsmentioning

confidence: 82%

Immobilization of cell‐binding peptides on poly‐ε‐caprolactone film surface to biomimic the peripheral nervous system

Luca

Stevens

Schroeder

et al. 2012

J Biomedical Materials Res

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Cell-material interactions are crucial for cell adhesion and proliferation on biomaterial surfaces. Immobilization of biomolecules leads to the formation of biomimetic substrates, improving cell response. We introduced RGD (Arg-Gly-Asp) sequences on poly-ε-caprolactone (PCL) film surfaces using thiol chemistry to enhance Schwann cell (SC) response. XPS elemental analysis indicated an estimate of 2-3% peptide functionalization on the PCL surface, comparable with carbodiimide chemistry. Contact angle was not remarkably reduced; hence, cell response was only affected by chemical cues on the film surface. Adhesion and proliferation of Schwann cells were enhanced after PCL modification. Particularly, RGD immobilization increased cell attachment up to 40% after 6 h of culture. It was demonstrated that SC morphology changed from round to very elongated shape when surface modification was carried out, with an increase in the length of cellular processes up to 50% after 5 days of culture. Finally RGD immobilization triggered the formation of focal adhesion related to higher cell spreading. In summary, this study provides a method for immobilization of biomolecules on PCL films to be used in peripheral nerve repair, as demonstrated by the enhanced response of Schwann cells.

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Section: Resultsmentioning

confidence: 82%

Immobilization of cell‐binding peptides on poly‐ε‐caprolactone film surface to biomimic the peripheral nervous system

Luca

Stevens

Schroeder

et al. 2012

J Biomedical Materials Res

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“…Our application of NEXAFS to concentrated solutions builds on the recent realisation that chemical shis in atomic core level binding energies, which can be measured by X-ray photoelectron spectroscopy (XPS), [20][21][22] provide incisive information about the inuence of hydrogen bonding and proton transfer on the structure of the organic solid state. [23][24][25][26][27][28] High resolution X-ray spectroscopies that probe core levels are generally sensitive to the local electronic structure around, and bonding by, the element that is excited in the atomic core. The X-ray absorption process underlying NEXAFS is the excitation of atomic core electrons (for light elements such as C, N and O the 1s electrons) to unoccupied valence orbitals; this can be readily interpreted by the use of molecular orbital calculations.…”

Section: Introductionmentioning

confidence: 99%

Self-association of organic solutes in solution: a NEXAFS study of aqueous imidazole

et al. 2015

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N K-edge near-edge X-ray absorption fine-structure (NEXAFS) spectra of imidazole in concentrated aqueous solutions have been acquired. The NEXAFS spectra of the solution species differ significantly from those of imidazole monomers in the gas phase and in the solid state of imidazole, demonstrating the strong sensitivity of NEXAFS to the local chemical and structural environment. In a concentration range from 0.5 to 8.2 mol L(-1) the NEXAFS spectrum of aqueous imidazole does not change strongly, confirming previous suggestions that imidazole self-associates are already present at concentrations more dilute than the range investigated here. We show that various types of electronic structure calculations (Gaussian, StoBe, CASTEP) provide a consistent and complete interpretation of all features in the gas phase and solid state spectra based on ground state electronic structure. This suggests that such computational modelling of experimental NEXAFS will permit an incisive analysis of the molecular interactions of organic solutes in solutions. It is confirmed that microhydrated clusters with a single imidazole molecule are poor models of imidazole in aqueous solution. Our analysis indicates that models including both a hydrogen-bonded network of hydrate molecules, and imidazole-imidazole interactions, are necessary to explain the electronic structure evident in the NEXAFS spectra.

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“…Analysis of the data was carried out with Casa XPS software [47] using a linear background and GL(30) line shape. [47] Samples were referenced following the procedure outlined previously, [17,19,25] giving the nitro group (NO 2 ) at 406.3 eV for benzoic acid materials. Repeatability of the peak positions was AE 0.1 eV.…”

Section: Methodsmentioning

confidence: 99%

“…With 4-aminobenzoic acid as the acceptor base, two photoemission peaks arise, associated with the two types of nitrogen moieties present, namely the NH 2 acceptor and the NO 2 groups of the donor molecules (Figure 1 a). The N1s binding energy of the NH 2 group occurs around 399.5 eV, which is the characteristic value [24,25] for an unprotonated amino group. The spectrum with 3,5-diaminobenzoic acid exhibits an additional peak at a Figure 1.…”

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confidence: 99%

“…[*] Dr. J. S. Stevens, Dr. C. C. Seaton binding energy of 401.9 eV (Figure 1 b), which is representative of a protonated amino group. [17,25] Proton transfer from the Brønsted acid to half of the amino groups has resulted in a substantial core-level binding energy shift of + 2.4 eV ( Figure 1). The rationale for selecting further members of a series of 15 acid/base phases was to cover a very wide range of pK a differences (DpK a ) between Brønsted acid and base components.…”

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confidence: 99%

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Crystallography Aided by Atomic Core‐Level Binding Energies: Proton Transfer versus Hydrogen Bonding in Organic Crystal Structures

et al. 2011

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Ionisch oder H‐verbrückt? Der Transfer von Brønsted‐Protonen zu Stickstoffakzeptoren in organischen Kristallen verursacht starke Verschiebungen der Bindungsenergien des N1s‐Rumpfniveaus. Eine Untersuchung von 15 organischen Cokristall‐ und Salzsystemen zeigt, dass Röntgen‐Photoelektronenspektroskopie ergänzend zur Röntgenkristallographie genutzt werden kann, um Protonentransfer von Wasserstoffbrücken in kondensierter Materie zu unterscheiden (siehe Bild).

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Detection of Free Base Surface Enrichment of a Pharmaceutical Salt by X-ray Photoelectron Spectroscopy (XPS)

Cited by 13 publications

References 11 publications

Immobilization of cell‐binding peptides on poly‐ε‐caprolactone film surface to biomimic the peripheral nervous system

Immobilization of cell‐binding peptides on poly‐ε‐caprolactone film surface to biomimic the peripheral nervous system

Self-association of organic solutes in solution: a NEXAFS study of aqueous imidazole

Crystallography Aided by Atomic Core‐Level Binding Energies: Proton Transfer versus Hydrogen Bonding in Organic Crystal Structures

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