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Abdul Basit M, Aanish Ali M, Masroor Z, Tariq Z, Ho Bang J. Quantum dot-sensitized solar cells: a review on interfacial engineering strategies for boosting efficiency. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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2
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van Rijt MMJ, Oosterlaken BM, Friedrich H, de With G. Controlled titration-based ZnO formation. CrystEngComm 2021; 23:3340-3348. [PMID: 34093087 PMCID: PMC8107948 DOI: 10.1039/d1ce00222h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 03/22/2021] [Indexed: 11/21/2022]
Abstract
Hexamethylenetetramine (HMTA) is commonly used as a base releasing agent for the synthesis of ZnO under mild aqueous conditions. HMTA hydrolysis leads to gradual formation of a base during the reaction. Use of HMTA, however, does have limitations: HMTA hydrolysis yields both formaldehyde and ammonia, it provides no direct control over the ammonia addition rate or the total amount of ammonia added during the reaction, it results in a limited applicable pH range and it dictates the accessible reaction temperatures. To overcome these restrictions, this work presents a direct base titration strategy for ZnO synthesis in which a continuous base addition rate is maintained. Using this highly flexible strategy, wurtzite ZnO can be synthesized at a pH >5.5 using either KOH or ammonia as a base source at various addition rates and reaction pH values. In situ pH measurements suggest a similar reaction mechanism to HMTA-based synthesis, independent of the varied conditions. The type and concentration of the base used for titration affect the reaction product, with ammonia showing evidence of capping behaviour. Optimizing this strategy, we are able to influence and direct the crystal shape and significantly increase the product yield to 74% compared to the ∼13% obtained by the reference HMTA reaction.
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Affiliation(s)
- Mark M J van Rijt
- Laboratory of Physical Chemistry, Centre for Multiscale Electron Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P. O. Box 513 Eindhoven 5600 MB The Netherlands
| | - Bernette M Oosterlaken
- Laboratory of Physical Chemistry, Centre for Multiscale Electron Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P. O. Box 513 Eindhoven 5600 MB The Netherlands
| | - Heiner Friedrich
- Laboratory of Physical Chemistry, Centre for Multiscale Electron Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P. O. Box 513 Eindhoven 5600 MB The Netherlands
| | - Gijsbertus de With
- Laboratory of Physical Chemistry, Centre for Multiscale Electron Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P. O. Box 513 Eindhoven 5600 MB The Netherlands
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3
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Nancy Anna Anasthasiya A, Ramya S, Rai P, Jeyaprakash B. ZnO nanowires: Synthesis and charge transfer mechanism in the detection of ammonia vapour. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2017.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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4
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Ekimova M, Quevedo W, Szyc Ł, Iannuzzi M, Wernet P, Odelius M, Nibbering ETJ. Aqueous Solvation of Ammonia and Ammonium: Probing Hydrogen Bond Motifs with FT-IR and Soft X-ray Spectroscopy. J Am Chem Soc 2017; 139:12773-12783. [PMID: 28810120 DOI: 10.1021/jacs.7b07207] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In a multifaceted investigation combining local soft X-ray and vibrational spectroscopic probes with ab initio molecular dynamics simulations, hydrogen-bonding interactions of two key principal amine compounds in aqueous solution, ammonia (NH3) and ammonium ion (NH4+), are quantitatively assessed in terms of electronic structure, solvation structure, and dynamics. From the X-ray measurements and complementary determination of the IR-active hydrogen stretching and bending modes of NH3 and NH4+ in aqueous solution, the picture emerges of a comparatively strongly hydrogen-bonded NH4+ ion via N-H donating interactions, whereas NH3 has a strongly accepting hydrogen bond with one water molecule at the nitrogen lone pair but only weakly N-H donating hydrogen bonds. In contrast to the case of hydrogen bonding among solvent water molecules, we find that energy mismatch between occupied orbitals of both the solutes NH3 and NH4+ and the surrounding water prevents strong mixing between orbitals upon hydrogen bonding and, thus, inhibits substantial charge transfer between solute and solvent. A close inspection of the calculated unoccupied molecular orbitals, in conjunction with experimentally measured N K-edge absorption spectra, reveals the different nature of the electronic structural effects of these two key principal amine compounds imposed by hydrogen bonding to water, where a pH-dependent excitation energy appears to be an intrinsic property. These results provide a benchmark for hydrogen bonding of other nitrogen-containing acids and bases.
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Affiliation(s)
- Maria Ekimova
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy , Max Born Strasse 2A, 12489 Berlin, Germany
| | - Wilson Quevedo
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Łukasz Szyc
- Magnosco c/o LTB Lasertechnik Berlin GmbH , Am Studio 2c, 12489 Berlin, Germany
| | - Marcella Iannuzzi
- Institute of Physical Chemistry, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Philippe Wernet
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Michael Odelius
- Department of Physics, Stockholm University , AlbaNova University Center, 106 91 Stockholm, Sweden
| | - Erik T J Nibbering
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy , Max Born Strasse 2A, 12489 Berlin, Germany
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5
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Böttcher S, Vita H, Weser M, Bisti F, Dedkov YS, Horn K. Adsorption of Water and Ammonia on Graphene: Evidence for Chemisorption from X-ray Absorption Spectra. J Phys Chem Lett 2017; 8:3668-3672. [PMID: 28732444 DOI: 10.1021/acs.jpclett.7b01085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
While the bonding of molecular adsorbates to graphene has so far been characterized as physisorption, our study of adsorbed ammonia and water using near-edge X-ray absorption spectroscopy provides unambiguous evidence for a chemical contribution to the adsorption bond. We use the situation, unique to graphene, to characterize the unoccupied valence band states of the partners in the bond on the basis of the complementary adsorbate and substrate X-ray absorption K edges. New adsorbate-induced features on the substrate (carbon) K edge are interpreted as hybrid states in terms of a simple model of chemical interaction.
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Affiliation(s)
- Stefan Böttcher
- Fritz Haber Institut of the Max Planck Society , 14195 Berlin, Germany
- SPECS Surface Nano Analysis GmbH , 13355 Berlin, Germany
| | - Hendrik Vita
- Fritz Haber Institut of the Max Planck Society , 14195 Berlin, Germany
| | - Martin Weser
- Fritz Haber Institut of the Max Planck Society , 14195 Berlin, Germany
| | - Federico Bisti
- Dipartimento di Science Fisiche e Chemiche, Università dell'Aquila , 67100 L'Aquila, Italy
| | - Yuriy S Dedkov
- Fritz Haber Institut of the Max Planck Society , 14195 Berlin, Germany
- Fachbereich Physik, Universität Konstanz , 78464 Konstanz, Germany
| | - Karsten Horn
- Fritz Haber Institut of the Max Planck Society , 14195 Berlin, Germany
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6
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Li H, Zhao K, Tian S, Zeng D, Pang A, Wang X, Xie C. Origin of the efficient catalytic thermal decomposition of ammonium perchlorate over (2−1−10) facets of ZnO nanosheets: surface lattice oxygen. RSC Adv 2017. [DOI: 10.1039/c7ra07906k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
A proposed classical catalytic mechanism based on surface lattice oxygen reveals that AP decomposition is promoted more by ZnO nanosheets than ZnS nanosheets.
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Affiliation(s)
- Haitao Li
- State Key Laboratory of Materials Processing and Die & Mould Technology
- Nanomaterials and Smart Sensors Research Lab (NSSRL)
- Department of Materials Science and Engineering
- Huazhong University of Science and Technology (HUST)
- Wuhan 430074
| | - Kun Zhao
- State Key Laboratory of Materials Processing and Die & Mould Technology
- Nanomaterials and Smart Sensors Research Lab (NSSRL)
- Department of Materials Science and Engineering
- Huazhong University of Science and Technology (HUST)
- Wuhan 430074
| | - Shouqin Tian
- State Key Laboratory of Silicate Materials for Architectures
- Wuhan University of Technology
- Wuhan 430070
- People's Republic of China
| | - Dawen Zeng
- State Key Laboratory of Materials Processing and Die & Mould Technology
- Nanomaterials and Smart Sensors Research Lab (NSSRL)
- Department of Materials Science and Engineering
- Huazhong University of Science and Technology (HUST)
- Wuhan 430074
| | - Aimin Pang
- Hubei Institute of Aerospace Chemotechnology
- Xiangyang 441003
- People's Republic of China
| | - Xiaoxia Wang
- State Key Laboratory of Materials Processing and Die & Mould Technology
- Nanomaterials and Smart Sensors Research Lab (NSSRL)
- Department of Materials Science and Engineering
- Huazhong University of Science and Technology (HUST)
- Wuhan 430074
| | - Changsheng Xie
- State Key Laboratory of Materials Processing and Die & Mould Technology
- Nanomaterials and Smart Sensors Research Lab (NSSRL)
- Department of Materials Science and Engineering
- Huazhong University of Science and Technology (HUST)
- Wuhan 430074
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7
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Ostapenko A, Klöffel T, Eußner J, Harms K, Dehnen S, Meyer B, Witte G. Etching of Crystalline ZnO Surfaces upon Phosphonic Acid Adsorption: Guidelines for the Realization of Well-Engineered Functional Self-Assembled Monolayers. ACS APPLIED MATERIALS & INTERFACES 2016; 8:13472-13483. [PMID: 27159837 DOI: 10.1021/acsami.6b02190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Functionalization of metal oxides by means of covalently bound self-assembled monolayers (SAMs) offers a tailoring of surface electronic properties such as their work function and, in combination with its large charge carrier mobility, renders ZnO a promising conductive oxide for use as transparent electrode material in optoelectronic devices. In this study, we show that the formation of phosphonic acid-anchored SAMs on ZnO competes with an unwanted chemical side reaction, leading to the formation of surface precipitates and severe surface damage at prolonged immersion times of several days. Combining atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal desorption spectroscopy (TDS), the stability and structure of the aggregates formed upon immersion of ZnO single crystal surfaces of different orientations [(0001̅), (0001), and (101̅0)] in phenylphosphonic acid (PPA) solution were studied. By intentionally increasing the immersion time to more than 1 week, large crystalline precipitates are formed, which are identified as zinc phosphonate. Moreover, the energetics and the reaction pathway of this transformation have been evaluated using density functional theory (DFT), showing that zinc phosphonate is thermodynamically more favorable than phosphonic acid SAMs on ZnO. Precipitation is also found for phosphonic acids with fluorinated aromatic backbones, while less precipitation occurs upon formation of SAMs with phenylphosphinic anchoring units. By contrast, no precipitates are formed when PPA monolayer films are prepared by sublimation under vacuum conditions, yielding smooth surfaces without noticeable etching.
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Affiliation(s)
- Alexandra Ostapenko
- Fachbereich Physik, Molekulare Festkörperphysik and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg , Renthof 7, 35032 Marburg, Germany
| | - Tobias Klöffel
- Interdisciplinary Center for Molecular Materials (ICMM) and Computer-Chemistry-Center (CCC), Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg , Nägelsbachstrasse 25, 91052 Erlangen, Germany
| | - Jens Eußner
- Fachbereich Chemie and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
| | - Klaus Harms
- Fachbereich Chemie and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
| | - Stefanie Dehnen
- Fachbereich Chemie and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
| | - Bernd Meyer
- Interdisciplinary Center for Molecular Materials (ICMM) and Computer-Chemistry-Center (CCC), Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg , Nägelsbachstrasse 25, 91052 Erlangen, Germany
| | - Gregor Witte
- Fachbereich Physik, Molekulare Festkörperphysik and Wissenschaftliches Zentrum für Materialwissenschaften (WZMW), Philipps-Universität Marburg , Renthof 7, 35032 Marburg, Germany
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8
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Effects of interface modification with self-assembled monolayers on the photovoltaic performance of CdS quantum dots sensitized solar cells. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.02.190] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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9
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Sun L, He H, Hu L, Ye Z. Evidence for the carbon–nitrogen complex in ZnO nanostructures with very high nitrogen doping. Phys Chem Chem Phys 2013; 15:1369-73. [DOI: 10.1039/c2cp43657d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Baio JE, Weidner T, Baugh L, Gamble LJ, Stayton PS, Castner DG. Probing the orientation of electrostatically immobilized Protein G B1 by time-of-flight secondary ion spectrometry, sum frequency generation, and near-edge X-ray adsorption fine structure spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:2107-12. [PMID: 22148958 PMCID: PMC3269520 DOI: 10.1021/la203907t] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
To fully develop techniques that provide an accurate description of protein structure at a surface, we must start with a relatively simple model system before moving to increasingly complex systems. In this study, X-ray photoelectron spectroscopy (XPS), sum frequency generation spectroscopy (SFG), near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to probe the orientation of Protein G B1 (6 kDa) immobilized onto both amine (NH(3)(+)) and carboxyl (COO(-)) functionalized gold. Previously, we have shown that we could successfully control orientation of a similar Protein G fragment via a cysteine-maleimide bond. In this investigation, to induce opposite end-on orientations, a charge distribution was created within the Protein G B1 fragment by first substituting specific negatively charged amino acids with neutral amino acids and then immobilizing the protein onto two oppositely charged self-assembled monolayer (SAM) surfaces (NH(3)(+) and COO(-)). Protein coverage, on both surfaces, was monitored by the change in the atomic % N, as determined by XPS. Spectral features within the SFG spectra, acquired for the protein adsorbed onto a NH(3)(+)-SAM surface, indicates that this electrostatic interaction does induce the protein to form an oriented monolayer on the SAM substrate. This corresponded to the polarization dependence of the spectral feature related to the NEXAFS N(1s)-to-π* transition of the β-sheet peptide bonds within the protein layer. ToF-SIMS data demonstrated a clear separation between the two samples based on the intensity differences of secondary ions stemming from amino acids located asymmetrically within Protein G B1 (methionine: 62 and 105 m/z; tyrosine: 107 and 137 m/z; leucine: 86 m/z). For a more quantitative examination of orientation, we developed a ratio comparing the sum of the intensities of secondary-ions stemming from the amino acid residues at either end of the protein. The 2-fold increase in this ratio, observed between the protein covered NH(3)(+) and COO(-) SAMs, indicates opposite orientations of the Protein G B1 fragment on the two different surfaces.
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Affiliation(s)
- Joe E. Baio
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Chemical Engineering, University of Washington, Seattle
| | - Tobias Weidner
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle
| | - Loren Baugh
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle
| | - Lara J. Gamble
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle
| | - Patrick S. Stayton
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle
| | - David G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Chemical Engineering, University of Washington, Seattle
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle
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11
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Baugh L, Weidner T, Baio J, Nguyen PC, Gamble LJ, Stayton PS, Castner DG. Probing the orientation of surface-immobilized protein G B1 using ToF-SIMS, sum frequency generation, and NEXAFS spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:16434-41. [PMID: 20384305 PMCID: PMC2911509 DOI: 10.1021/la1007389] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The ability to orient active proteins on surfaces is a critical aspect of many medical technologies. An important related challenge is characterizing protein orientation in these surface films. This study uses a combination of time-of-flight secondary ion mass spectrometry (ToF-SIMS), sum frequency generation (SFG) vibrational spectroscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to characterize the orientation of surface-immobilized Protein G B1, a rigid 6 kDa domain that binds the Fc fragment of IgG. Two Protein G B1 variants with a single cysteine introduced at either end were immobilized via the cysteine thiol onto maleimide-oligo(ethylene glycol)-functionalized gold and bare gold substrates. X-ray photoelectron spectroscopy was used to measure the amount of immobilized protein, and ToF-SIMS was used to measure the amino acid composition of the exposed surface of the protein films and to confirm covalent attachment of protein thiol to the substrate maleimide groups. SFG and NEXAFS were used to characterize the ordering and orientation of peptide or side chain bonds. On both substrates and for both cysteine positions, ToF-SIMS data showed enrichment of mass peaks from amino acids located at the end of the protein opposite to the cysteine surface position as compared with nonspecifically immobilized protein, indicating end-on protein orientations. Orientation on the maleimide substrate was enhanced by increasing pH (7.0-9.5) and salt concentration (0-1.5 M NaCl). SFG spectral peaks characteristic of ordered α-helix and β-sheet elements were observed for both variants but not for cysteine-free wild type protein on the maleimide surface. The phase of the α-helix and β-sheet peaks indicated a predominantly upright orientation for both variants, consistent with an end-on protein binding configuration. Polarization dependence of the NEXAFS signal from the N 1s to π* transition of β-sheet peptide bonds also indicated protein ordering, with an estimated tilt angle of inner β-strands of 40-50° for both variants (one variant more tilted than the other), consistent with SFG results. The combined results demonstrate the power of using complementary techniques to probe protein orientation on surfaces.
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Affiliation(s)
- Loren Baugh
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering, University of Washington, Seattle, WA 98195
| | - Tobias Weidner
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering, University of Washington, Seattle, WA 98195
| | - J.E. Baio
- National ESCA and Surface Analysis Center for Biomedical Problems, Chemical Engineering, University of Washington, Seattle, WA 98195
| | - Phuong Cac Nguyen
- National ESCA and Surface Analysis Center for Biomedical Problems, Chemical Engineering, University of Washington, Seattle, WA 98195
| | - Lara J. Gamble
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering, University of Washington, Seattle, WA 98195
| | - Patrick S. Stayton
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering, University of Washington, Seattle, WA 98195
| | - David G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering, University of Washington, Seattle, WA 98195
- National ESCA and Surface Analysis Center for Biomedical Problems, Chemical Engineering, University of Washington, Seattle, WA 98195
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12
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Baio J, Weidner T, Samuel N, McCrea K, Baugh L, Stayton PS, Castner DG. Multi-technique Characterization of Adsorbed Peptide and Protein Orientation: LK3 10 and Protein G B1. JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY. B, NANOTECHNOLOGY & MICROELECTRONICS : MATERIALS, PROCESSING, MEASUREMENT, & PHENOMENA : JVST B 2010; 28:C5D1. [PMID: 23976839 PMCID: PMC3749848 DOI: 10.1116/1.3456176] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The ability to orient biologically active proteins on surfaces is a major challenge in the design, construction, and successful deployment of many medical technologies. As methods to orient biomolecules are developed, it is also essential to develop techniques that can an accurately determine the orientation and structure of these materials. In this study, two model protein and peptide systems are presented to highlight the strengths of three surface analysis techniques for characterizing protein films: time-of-flight secondary ion mass spectrometry (ToF-SIMS), sum-frequency generation (SFG) vibrational spectroscopy, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. First, the orientation of Protein G B1, a rigid 6 kDa domain covalently attached to a maleimide-functionalized self-assembled monolayer, was examined using ToF-SIMS. Although the thickness of the Protein G layer was similar to the ToF-SIMS sampling depth, orientation of Protein G was successfully determined by analyzing the C2H5S+ intensity, a secondary ion derived from a methionine residue located at one end of the protein. Next, the secondary structure of a 13-mer leucine-lysine peptide (LK310) adsorbed onto hydrophilic quartz and hydrophobic fluorocarbon surfaces was examined. SFG spectra indicated that the peptide's lysine side chains were ordered on the quartz surface, while the peptide's leucine side chains were ordered on the fluorocarbon surface. NEXAFS results provided complementary information about the structure of the LK310 film and the orientations of amide bonds within the LK310 peptide.
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Affiliation(s)
- J.E. Baio
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Chemical, University of Washington, Seattle, WA 98195
| | - T. Weidner
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle, WA 98195
| | - N.T. Samuel
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Chemical, University of Washington, Seattle, WA 98195
| | - Keith McCrea
- Emergence Venture Partners, LLC, Berkeley, CA 94710, USA
| | - Loren Baugh
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle, WA 98195
| | - Patrick S. Stayton
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle, WA 98195
| | - David G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Chemical, University of Washington, Seattle, WA 98195
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Seattle, WA 98195
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13
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Weidner T, Samuel NT, McCrea K, Gamble LJ, Ward RS, Castner DG. Assembly and structure of alpha-helical peptide films on hydrophobic fluorocarbon surfaces. Biointerphases 2010; 5:9-16. [PMID: 20408730 PMCID: PMC3912757 DOI: 10.1116/1.3317116] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The structure, orientation, and formation of amphiphilic alpha-helix model peptide films on fluorocarbon surfaces has been monitored with sum frequency generation (SFG) vibrational spectroscopy, near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, and x-ray photoelectron spectroscopy (XPS). The alpha-helix peptide is a 14-mer of hydrophilic lysine and hydrophobic leucine residues with a hydrophobic periodicity of 3.5. This periodicity yields a rigid amphiphilic peptide with leucine and lysine side chains located on opposite sides. XPS composition analysis confirms the formation of a peptide film that covers about 75% of the surface. NEXAFS data are consistent with chemically intact adsorption of the peptides. A weak linear dichroism of the amide pi( *) is likely due to the broad distribution of amide bond orientations inherent to the alpha-helical secondary structure. SFG spectra exhibit strong peaks near 2865 and 2935 cm(-1) related to aligned leucine side chains interacting with the hydrophobic surface. Water modes near 3200 and 3400 cm(-1) indicate ordering of water molecules in the adsorbed-peptide fluorocarbon surface interfacial region. Amide I peaks observed near 1655 cm(-1) confirm that the secondary structure is preserved in the adsorbed peptide. A kinetic study of the film formation process using XPS and SFG showed rapid adsorption of the peptides followed by a longer assembly process. Peptide SFG spectra taken at the air-buffer interface showed features related to well-ordered peptide films. Moving samples through the buffer surface led to the transfer of ordered peptide films onto the substrates.
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Affiliation(s)
- Tobias Weidner
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Newton T. Samuel
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Keith McCrea
- The Polymer Technology Group, Berkeley, CA 94710, USA
| | - Lara J. Gamble
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | | | - David G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Bioengineering and Chemical Engineering, University of Washington, Seattle, WA 98195, USA
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14
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Baio JE, Weidner T, Brison J, Graham D, Gamble LJ, Castner DG. Amine Terminated SAMs: Investigating Why Oxygen is Present in these Films. JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA 2009; 172:2-8. [PMID: 20161353 PMCID: PMC2776750 DOI: 10.1016/j.elspec.2009.02.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Self-assembled monolayers (SAMs) on gold prepared from amine-terminated alkanethiols have long been employed as model positively charged surfaces. Yet in previous studies significant amounts of unexpected oxygen containing species are always detected in amine terminated SAMs. Thus, the goal of this investigation was to determine the source of these oxygen species and minimize their presence in the SAM. The surface composition, structure, and order of amine-terminated SAMs on Au were characterized by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), sum frequency generation (SFG) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. XPS determined compositions of amine-terminated SAMs in the current study exhibited oxygen concentrations of 2.4 ± 0.4 atomic %, a substantially lower amount of oxygen than reported in previously published studies. High-resolution XPS results from the S(2p), C(1s) and N(1s) regions did not detect any oxidized species. Angle-resolved XPS indicated that the small amount of oxygen detected was located at or near the amine head group. Small amounts of oxidized nitrogen, carbon and sulfur secondary ions, as well as ions attributed to water, were detected in the ToF-SIMS data due to the higher sensitivity of ToF-SIMS. The lack of N-O, S-O, and C-O stretches in the SFG spectra are consistent with the XPS and ToF-SIMS results and together show that oxidation of the amine-terminated thiols alone can only account for, at most, a small fraction of the oxygen detected by XPS. Both the SFG and angle-dependent NEXAFS indicated the presence of gauche defects in the amine SAMs. However, the SFG spectral features near 2865 cm(-1), assigned to the stretch of the methylene group next to the terminal amine unit, demonstrate the SAM is reasonably ordered. The SFG results also show another broad feature near 3200 cm(-1) related to hydrogen-bonded water. From this multi-technique investigation it is clear that the majority of the oxygen detected within these amine-terminated SAMs arises from the presence of oxygen containing adsorbates such as tightly bound water.
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Affiliation(s)
- J. E. Baio
- National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Departments of Bioengineering and Chemical Engineering, Box 351750, Seattle, WA 98195
| | - T. Weidner
- National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Departments of Bioengineering and Chemical Engineering, Box 351750, Seattle, WA 98195
| | - J. Brison
- National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Departments of Bioengineering and Chemical Engineering, Box 351750, Seattle, WA 98195
| | - D.J. Graham
- Asemblon, 15340 NE 92 Street, Suite B, Redmond, WA 98052
| | - Lara J. Gamble
- National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Departments of Bioengineering and Chemical Engineering, Box 351750, Seattle, WA 98195
| | - David G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, University of Washington, Departments of Bioengineering and Chemical Engineering, Box 351750, Seattle, WA 98195
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Moreira NH, Dolgonos G, Aradi B, da Rosa AL, Frauenheim T. Toward an Accurate Density-Functional Tight-Binding Description of Zinc-Containing Compounds. J Chem Theory Comput 2009; 5:605-14. [DOI: 10.1021/ct800455a] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ney H. Moreira
- Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany
| | - Grygoriy Dolgonos
- Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany
| | - Bálint Aradi
- Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany
| | - Andreia L. da Rosa
- Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany
| | - Thomas Frauenheim
- Bremen Center for Computational Materials Science, University of Bremen, Am Fallturm 1, 28359 Bremen, Germany
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16
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Westerberg S, Wang C, Chou K, Somorjai GA. High-Pressure Ammonia Adsorption and Dissociation on Clean Fe(111) and Oxygen-Precovered Fe(111) Studied by Sum Frequency Generation Vibrational Spectroscopy. J Phys Chem B 2004; 108:6374-80. [DOI: 10.1021/jp037357k] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Staffan Westerberg
- Department of Chemistry, University of Berkeley, and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, Laboratory of Materials and Semiconductor Physics, Royal Institute of Technology, Electrum 229, SE-164 40, Sweden, and Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100080, China
| | - Chen Wang
- Department of Chemistry, University of Berkeley, and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, Laboratory of Materials and Semiconductor Physics, Royal Institute of Technology, Electrum 229, SE-164 40, Sweden, and Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100080, China
| | - Keng Chou
- Department of Chemistry, University of Berkeley, and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, Laboratory of Materials and Semiconductor Physics, Royal Institute of Technology, Electrum 229, SE-164 40, Sweden, and Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100080, China
| | - Gabor A. Somorjai
- Department of Chemistry, University of Berkeley, and Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, Laboratory of Materials and Semiconductor Physics, Royal Institute of Technology, Electrum 229, SE-164 40, Sweden, and Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100080, China
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