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Javorskis T, Rakickas T, Janku̅naitė A, Vaitekonis Š, Ulčinas A, Orentas E. Maskless, Reusable Visible-Light Direct-Write Stamp for Microscale Surface Patterning. ACS APPLIED MATERIALS & INTERFACES 2023; 15:11259-11267. [PMID: 36797999 PMCID: PMC11008783 DOI: 10.1021/acsami.2c20568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
We report a straightforward method for creating large-area, microscale resolution patterns of functional amines on self-assembled monolayers by the photoinduced local acidification of a flat elastomeric stamp enriched with photoacid. The limited diffusivity of the photoactivated merocyanine acid in poly(dimethylsiloxane) (PDMS) enabled to confine efficient deprotection of N-tert-butyloxycarbonyl amino group (N-Boc) to line widths below 10 μm. The experimental setup is very simple and is built around the conventional HD-DVD optical pickup. The method allows cost-efficient, maskless, large-area chemical patterning while avoiding potentially cytotoxic photochemical reaction products. The activation of the embedded photoacid occurs within the stamp upon illumination with the laser beam and the process is fully reversible. Preliminary positive results highlight the possibility of repeatable use of the same stamp for the creation of different patterns.
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Affiliation(s)
- Tomas Javorskis
- Department
of Nanoengineering, Center for Physical
Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
| | - Tomas Rakickas
- Department
of Nanoengineering, Center for Physical
Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
| | - Alberta Janku̅naitė
- Department
of Organic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania
| | - Šaru̅nas Vaitekonis
- Department
of Nanoengineering, Center for Physical
Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
| | - Artu̅ras Ulčinas
- Department
of Nanoengineering, Center for Physical
Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
| | - Edvinas Orentas
- Department
of Nanoengineering, Center for Physical
Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
- Department
of Organic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania
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2
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Son YJ, Kang H, Seong S, Han S, Lee NS, Noh J. Thermally Driven Structural Order of Oligo(Ethylene Glycol)-Terminated Alkanethiol Monolayers on Au(111) Prepared by Vapor Deposition. Molecules 2022; 27:molecules27175377. [PMID: 36080145 PMCID: PMC9457651 DOI: 10.3390/molecules27175377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/22/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
To probe the effects of deposition temperature on the formation and structural order of self-assembled monolayers (SAMs) on Au(111) prepared by vapor deposition of 2-(2-methoxyethoxy)ethanethiol (CH3O(CH2)2O(CH2)2SH, EG2) for 24 h, we examined the surface structure and electrochemical behavior of the resulting EG2 SAMs using scanning tunneling microscopy (STM) and cyclic voltammetry (CV). STM observations clearly revealed that EG2 SAMs vapor-deposited on Au(111) at 298 K were composed of a disordered phase on the entire Au surface, whereas those formed at 323 K showed improved structural order, showing a mixed phase of ordered and disordered phases. Moreover, at 348 K, uniform and highly ordered EG2 SAMs on Au(111) were formed with a (2 × 3√3) packing structure. CV measurements showed sharp reductive desorption (RD) peaks at −0.818, −0.861, and −0.880 V for EG2 SAM-modified Au electrodes formed at 298, 323, and 348 K, respectively. More negative potential shifts of RD peaks with increasing deposition temperature are attributed to an increase in van der Waals interactions between EG2 molecular backbones resulting from the improved structural quality of EG2 SAMs. Our results obtained herein provide new insights into the formation and thermally driven structural order of oligo(ethylene glycol)-terminated SAMs vapor-deposited on Au(111).
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Affiliation(s)
- Young Ji Son
- Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
| | - Hungu Kang
- Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea
| | - Sicheon Seong
- Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
| | - Seulki Han
- Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
| | - Nam-Suk Lee
- National Institute for Nanomaterials Technology, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Jaegeun Noh
- Department of Chemistry, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
- Institute of Nano Science and Technology, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea
- Correspondence:
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3
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Javorskis T, Rakickas T, Jankūnaitė A, Talaikis M, Niaura G, Ulčinas A, Orentas E. Meso-scale surface patterning of self-assembled monolayers with water. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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4
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Cho N, Kang S, Lee H, Kang H, Kong GD, Yoon HJ. Superexchange Coupling-Induced Enhancements of Thermoelectric Performance in Saturated Molecules. NANO LETTERS 2021; 21:360-366. [PMID: 33275442 DOI: 10.1021/acs.nanolett.0c03736] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
To develop thermoelectric devices, it is of the utmost importance to design organic building blocks to have efficient thermopower. Whereas conjugated and aromatic molecules with intrinsic narrow band gaps are attractive candidates to achieve efficient thermoelectric properties, saturated molecules are usually avoided owing to intrinsically poor thermopower. Here we demonstrate that thermopower of saturated molecules can be enhanced by superexchange coupling. Specifically, thermoelectric properties of large-area junctions that contain self-assembled monolayers of oligo(ethylene glycol) thiolates and alkanethiolates are compared. Through large-area thermopower measurements using a liquid metal top electrode, we show that the superexchange coupling enhances the Seebeck coefficient and counterintuitively leads to an increase in the Seebeck coefficient with increasing the length in a certain conformation. The improved thermoelectric performance is attributed to the superexchange-induced enhanced ability to mediate metal wave function in junctions. Our work offers new insights for improving the thermoelectric performance of nonconjugated, saturated molecules.
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Affiliation(s)
- Nayoung Cho
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Seohyun Kang
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hyunju Lee
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hungu Kang
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Gyu Don Kong
- Department of Chemistry, Korea University, Seoul 02841, Korea
| | - Hyo Jae Yoon
- Department of Chemistry, Korea University, Seoul 02841, Korea
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5
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Lee HH, Gavutis M, Ruželė Ž, Valiokas R, Liedberg B. Mixed Self-Assembled Monolayers with Terminal Deuterated Anchors: Characterization and Probing of Model Lipid Membrane Formation. J Phys Chem B 2018; 122:8201-8210. [DOI: 10.1021/acs.jpcb.8b05097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hung-Hsun Lee
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, 581 83 Linköping, Sweden
| | - Martynas Gavutis
- Department of Nanoengineering, Center for Physical Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
| | - Živilė Ruželė
- Department of Nanoengineering, Center for Physical Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
| | - Ramu̅nas Valiokas
- Department of Nanoengineering, Center for Physical Sciences and Technology, Savanorių 231, LT-02300 Vilnius, Lithuania
| | - Bo Liedberg
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, 581 83 Linköping, Sweden
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6
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Yeung SY, Ederth T, Pan G, Cicėnaitė J, Cárdenas M, Arnebrant T, Sellergren B. Reversible Self-Assembled Monolayers (rSAMs) as Robust and Fluidic Lipid Bilayer Mimics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:4107-4115. [PMID: 29553755 DOI: 10.1021/acs.langmuir.8b00226] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Lipid bilayers, forming the outer barrier of cells, display a wide array of proteins and carbohydrates for modulating interfacial biological interactions. Formed by the spontaneous self-assembly of lipid molecules, these bilayers feature liquid crystalline order, while retaining a high degree of lateral mobility. Studies of these dynamic phenomena have been hampered by the fragility and instability of corresponding biomimetic cell membrane models. Here, we present the construct of a series of oligoethylene glycol-terminated reversible self-assembled monolayers (rSAMs) featuring lipid-bilayer-like fluidity, while retaining air and protein stability and resistance. These robust and ordered layers were prepared by simply immersing a carboxylic acid-terminated self-assembled monolayer into 5-50 μM aqueous ω-(4-ethylene glycol-phenoxy)-α-(4-amidinophenoxy)decane solutions. It is anticipated that this new class of robust and fluidic two-dimensional biomimetic surfaces will impact the design of rugged cell surface mimics and high-performance biosensors.
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Affiliation(s)
- Sing Yee Yeung
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and Society , Malmö University , 205 06 Malmö , Sweden
| | - Thomas Ederth
- Division of Molecular Physics, Department of Physics, Chemistry and Biology (IFM) , Linköping University , 581 83 Linköping , Sweden
| | - Guoqing Pan
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and Society , Malmö University , 205 06 Malmö , Sweden
| | - Judita Cicėnaitė
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and Society , Malmö University , 205 06 Malmö , Sweden
| | - Marité Cárdenas
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and Society , Malmö University , 205 06 Malmö , Sweden
| | - Thomas Arnebrant
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and Society , Malmö University , 205 06 Malmö , Sweden
| | - Börje Sellergren
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and Society , Malmö University , 205 06 Malmö , Sweden
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7
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Kankate L, Aguf A, Großmann H, Schnietz M, Tampé R, Turchanin A, Gölzhäuser A. Vapor Phase Exchange of Self-Assembled Monolayers for Engineering of Biofunctional Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3847-3854. [PMID: 28340533 DOI: 10.1021/acs.langmuir.6b04207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We show that 4'-nitro-1,1'-biphenyl-4-thiol self-assembled monolayers (NBPT SAMs) on gold can be exchanged with 11-(mercaptoundecyl)triethylene glycol (C11EG3OH) SAMs via vapor deposition (VD). The pristine and the exchanged SAMs obtained by VD as well as solution method (SM) were characterized by X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). Using surface plasmon resonance (SPR), it is shown that C11EG3OH SAMs on gold obtained by vapor deposition exchange (VDEx) have the same protein resistivity as SAMs obtained by the direct self-assembly process. As expected, the cross-linked NBPT SAM are found to be resistive to both exchange processes, VDEx and solution method exchange (SMEx). In this way, VDEx opens up an elegant and new approach of patterning SAM surfaces in situ at vacuum conditions without using any solvents. By combining electron irradiation-induced chemical lithography of NBPT SAMs with VDEx, biofunctional patterned substrates were engineered and used for immobilization of protein arrays.
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Affiliation(s)
- L Kankate
- Department of Physics, Physics of Supramolecular Systems and Surfaces, University of Bielefeld , 33615 Bielefeld, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - A Aguf
- Department of Physics, Physics of Supramolecular Systems and Surfaces, University of Bielefeld , 33615 Bielefeld, Germany
| | - H Großmann
- Institute of Biochemistry, Biocenter, Goethe-University , 60438 Frankfurt, Germany
| | - M Schnietz
- Department of Physics, Physics of Supramolecular Systems and Surfaces, University of Bielefeld , 33615 Bielefeld, Germany
| | - R Tampé
- Institute of Biochemistry, Biocenter, Goethe-University , 60438 Frankfurt, Germany
| | - A Turchanin
- Institute of Physical Chemistry, Friedrich Schiller University Jena , Lessingstr. 10, 07743 Jena, Germany
| | - A Gölzhäuser
- Department of Physics, Physics of Supramolecular Systems and Surfaces, University of Bielefeld , 33615 Bielefeld, Germany
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8
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Koutsoumpeli E, Tiede C, Murray J, Tang A, Bon RS, Tomlinson DC, Johnson S. Antibody Mimetics for the Detection of Small Organic Compounds Using a Quartz Crystal Microbalance. Anal Chem 2017; 89:3051-3058. [PMID: 28192970 DOI: 10.1021/acs.analchem.6b04790] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Conventional immunoassays rely on antibodies that provide high affinity, specificity, and selectivity against a target analyte. However, the use of antibodies for the detection of small-sized, nonimmunogenic targets, such as pharmaceuticals and environmental contaminants, presents a number of challenges. Recent advances in protein engineering have led to the emergence of antibody mimetics that offer the high affinity and specificity associated with antibodies, but with reduced batch-to-batch variability, high stability, and in vitro selection to ensure rapid discovery of binders against a wide range of targets. In this work we explore the potential of Affimers, a recent example of antibody mimetics, as suitable bioreceptors for the detection of small organic target compounds, here methylene blue. Target immobilization for Affimer characterization was achieved using long-chained alkanethiol linkers coupled with oligoethylene glycol (LCAT-OEG). Using quartz crystal microbalance with dissipation monitoring (QCM-D), we determine the affinity constant, KD, of the methylene blue Affimer to be comparable to that of antibodies. Further, we demonstrate the high selectivity of Affimers for its target in complex matrixes, here a limnetic sample. Finally, we demonstrate an Affimer-based competition assay, illustrating the potential of Affimers as bioreceptors in immunoassays for the detection of small-sized, nonimmunogenic compounds.
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Affiliation(s)
- Eleni Koutsoumpeli
- Department of Electronics, University of York , Heslington, York, YO10 5DD, United Kingdom
| | | | | | | | | | | | - Steven Johnson
- Department of Electronics, University of York , Heslington, York, YO10 5DD, United Kingdom
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9
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Cao HH, Nakatsuka N, Serino AC, Liao WS, Cheunkar S, Yang H, Weiss PS, Andrews AM. Controlled DNA Patterning by Chemical Lift-Off Lithography: Matrix Matters. ACS NANO 2015; 9:11439-54. [PMID: 26426585 DOI: 10.1021/acsnano.5b05546] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Nucleotide arrays require controlled surface densities and minimal nucleotide-substrate interactions to enable highly specific and efficient recognition by corresponding targets. We investigated chemical lift-off lithography with hydroxyl- and oligo(ethylene glycol)-terminated alkanethiol self-assembled monolayers as a means to produce substrates optimized for tethered DNA insertion into post-lift-off regions. Residual alkanethiols in the patterned regions after lift-off lithography enabled the formation of patterned DNA monolayers that favored hybridization with target DNA. Nucleotide densities were tunable by altering surface chemistries and alkanethiol ratios prior to lift-off. Lithography-induced conformational changes in oligo(ethylene glycol)-terminated monolayers hindered nucleotide insertion but could be used to advantage via mixed monolayers or double-lift-off lithography. Compared to thiolated DNA self-assembly alone or with alkanethiol backfilling, preparation of functional nucleotide arrays by chemical lift-off lithography enables superior hybridization efficiency and tunability.
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Affiliation(s)
- Huan H Cao
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Nako Nakatsuka
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Andrew C Serino
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Wei-Ssu Liao
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Sarawut Cheunkar
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Hongyan Yang
- Department of Psychiatry and Biobehavioral Health, Semel Institute for Neuroscience and Human Behavior, and Hatos Center for Neuropharmacology, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Paul S Weiss
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Materials Science and Engineering, University of California, Los Angeles , Los Angeles, California 90095, United States
| | - Anne M Andrews
- California NanoSystems Institute, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles , Los Angeles, California 90095, United States
- Department of Psychiatry and Biobehavioral Health, Semel Institute for Neuroscience and Human Behavior, and Hatos Center for Neuropharmacology, University of California, Los Angeles , Los Angeles, California 90095, United States
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10
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Solano I, Parisse P, Gramazio F, Cavalleri O, Bracco G, Castronovo M, Casalis L, Canepa M. Spectroscopic ellipsometry meets AFM nanolithography: about hydration of bio-inert oligo(ethylene glycol)-terminated self assembled monolayers on gold. Phys Chem Chem Phys 2015; 17:28774-81. [PMID: 26445913 DOI: 10.1039/c5cp04028k] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
An accurate thickness determination provides insight into the complex vertical morphology of OEG-terminated SAMs.
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Affiliation(s)
- Ilaria Solano
- Dipartimento di Fisica
- Università di Genova and CNISM
- Genova
- Italy
| | | | | | | | | | - Matteo Castronovo
- Department of Medical and Biological Sciences – University of Udine
- Udine
- Italy
| | | | - Maurizio Canepa
- Dipartimento di Fisica
- Università di Genova and CNISM
- Genova
- Italy
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11
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Modification of silicon oxide surfaces by monolayers of an oligoethylene glycol-terminated perfluoroalkyl silane. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2014.02.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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12
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Malysheva L, Kapitanchuk O, Onipko A. Three-dimensional networks of hydrogen bonds in periodic arrays of molecular modules containing amide-(ethylene glycol) and amide-(ethylene glycol)-amide: Ab initio picture. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2013.11.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Uzarski JR, Mello CM. Detection and Classification of Related Lipopolysaccharides via a Small Array of Immobilized Antimicrobial Peptides. Anal Chem 2012; 84:7359-66. [DOI: 10.1021/ac300987h] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joshua R. Uzarski
- U.S. Army Natick Solider Research, Development, and Engineering Center, Natick, Massachusetts 01760,
United States
- Chemistry and Biochemistry Department, University of Massachusetts Dartmouth, North Dartmouth,
Massachusetts 02747, United States
| | - Charlene M. Mello
- U.S. Army Natick Solider Research, Development, and Engineering Center, Natick, Massachusetts 01760,
United States
- Chemistry and Biochemistry Department, University of Massachusetts Dartmouth, North Dartmouth,
Massachusetts 02747, United States
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14
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Fyrner T, Lee HH, Mangone A, Ekblad T, Pettitt ME, Callow ME, Callow JA, Conlan SL, Mutton R, Clare AS, Konradsson P, Liedberg B, Ederth T. Saccharide-functionalized alkanethiols for fouling-resistant self-assembled monolayers: synthesis, monolayer properties, and antifouling behavior. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:15034-15047. [PMID: 22053781 DOI: 10.1021/la202774e] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We describe the synthesis of a series of mono-, di-, and trisaccharide-functionalized alkanethiols as well as the formation of fouling-resistant self-assembled monolayers (SAMs) from these. The SAMs were characterized using ellipsometry, wetting measurements, and infrared reflection-absorption spectroscopy (IRAS). We show that the structure of the carbohydrate moiety affects the packing density and that this also alters the alkane chain organization. Upon increasing the size of the sugar moieties (from mono- to di- and trisaccharides), the structural qualities of the monolayers deteriorated with increasing disorder, and for the trisaccharide, slow reorganization dynamics in response to changes in the environmental polarity were observed. The antifouling properties of these SAMs were investigated through protein adsorption experiments from buffer solutions as well as settlement (attachment) tests using two common marine fouling species, zoospores of the green macroalga Ulva linza and cypris larvae of the barnacle Balanus amphitrite. The SAMs showed overall good resistance to fouling by both the proteins and the tested marine organisms. To improve the packing density of the SAMs with bulky headgroups, we employed mixed SAMs where the saccharide-thiols are diluted with a filler molecule having a small 2-hydroxyethyl headgroup. This method also provides a means by which the steric availability of sugar moieties can be varied, which is of interest for specific interaction studies with surface-bound sugars. The results of the surface dilution study and the low nonspecific adsorption onto the SAMs both indicate the feasibility of this approach.
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Affiliation(s)
- Timmy Fyrner
- Division of Chemistry, IFM, Linköping University, SE-581 83 Linköping, Sweden
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15
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Protein resistant oligo(ethylene glycol) terminated self-assembled monolayers of thiols on gold by vapor deposition in vacuum. Biointerphases 2010; 5:30-36. [PMID: 20831346 DOI: 10.1116/1.3407483] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Protein resistant oligo(ethylene glycol) (OEG) terminated self-assembled monolayers (SAMs) of thiols on gold are commonly used for suppression of nonspecific protein adsorption in biology and biotechnology. The standard preparation for these SAMs is the solution method (SM) that involves immersion of the gold surface in an OEG solution. Here the authors present the preparation of 11-(mercaptoundecyl)-triethylene glycol [HS(CH(2))(11)(OCH(2)CH(2))(3)OH] SAMs on gold surface by vapor deposition (VD) in vacuum. They compare the properties of SAMs prepared by VD and SM using x-ray photoelectron spectroscopy (XPS), polarization modulation infrared reflection absorption spectroscopy, and surface plasmon resonance measurements. VD and SM SAMs exhibit similar packing density and show a similar resistance to the nonspecific adsorption of various proteins (bovine serum albumin, trypsin, and myoglobin) under physiological conditions. A very high sensitivity of the OEG SAMs to x-ray radiation is found, which allows tuning their protein resistance. These results show a new path to in situ engineering, analysis, and patterning of protein resistant OEG SAMs by high vacuum and ultrahigh vacuum techniques.
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16
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Wong LS, Janusz SJ, Sun S, Leggett GJ, Micklefield J. Nanoscale Biomolecular Structures on Self-Assembled Monolayers Generated from Modular Pegylated Disulfides. Chemistry 2010; 16:12234-43. [DOI: 10.1002/chem.200902439] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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17
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Analysing protein competition on self-assembled mono-layers studied with quartz crystal microbalance. Acta Biomater 2010; 6:3499-505. [PMID: 20332036 DOI: 10.1016/j.actbio.2010.03.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 02/10/2010] [Accepted: 03/18/2010] [Indexed: 11/23/2022]
Abstract
The mechanisms by which proteins adsorb to surfaces of biomaterials have long been of interest. The present work started with the premise that small/hard and large/soft proteins will yield different sets of normalized frequency shift and dissipation signals when studied with a quartz crystal microbalance. The aim was to evaluate the usefulness of these raw data to study protein competition using protein incubations in sequence and from mixtures of albumin (BSA) and gamma-globulin (BGG) at various ratios. Increasing the concentration of BSA decreases the adsorption of subsequently incubated BGG. For BSA/BGG mixtures the dissipation is similar for all logarithmic molar ratios BGG/BSA below 1 but soon decreases when the molar ratio of BSA/BGG (and opposite for the normalized frequency shift) is above 1, indicating preferential binding of BGG. Modelling indicated that differences in the film shear modulus and viscosity depend more on the properties of the self-assembling mono-layers (SAMs) than on the proteins. Films high in BSA tentatively differ in film shear modulus and viscosity from that of films high in BGG but only on the hydrophobic surfaces. The results were encouraging as the raw data were deemed to be able to point at protein adsorption competition.
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Sobota M, Wang X, Fekete M, Happel M, Meyer K, Wasserscheid P, Laurin M, Libuda J. Ordering and Phase Transitions in Ionic Liquid-Crystalline Films. Chemphyschem 2010; 11:1632-6. [DOI: 10.1002/cphc.201000144] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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19
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Brand I, Nullmeier M, Klüner T, Jogireddy R, Christoffers J, Wittstock G. Structural analysis of HS(CD(2))(12)(O-CH(2)-CH(2))(6)OCH(3) monolayers on gold by means of polarization modulation infrared reflection absorption spectroscopy. progress of the reaction with bromine. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:362-370. [PMID: 19711923 DOI: 10.1021/la9020993] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A self-assembled monolayer (SAM) on gold was formed with specifically perdeuterated hexaethylene glycol-terminated alkanethiol HS(CD(2))(12)(O-CH(2)-CH(2))(6)OCH(3) (D-OEG). The structure of the d-alkane and the oligoethylene glycol (OEG) parts of the molecule in a SAM was studied by means of polarization modulation infrared reflection absorption spectroscopy. The D-OEG monolayers are highly ordered and exist in a crystalline phase. The d-alkane chain adopts an all-trans conformation. Both, the d-alkane chain and long axis of the OEG part make an angle of 26.0 degrees +/- 1.5 degrees with respect to the surface normal, a value characteristic for the tilt of solid n-alkane thiols in the SAMs on Au. The positions of nu(as)(COC) and CH(2) wagging and rocking modes indicate a helical arrangement of the OEG chains. The D-OEG SAMs were exposed to 25 muM Br(2) in two ways: (i) by immersion into the Br(2) solution and (ii) in the galvanic cell Au|D-OEG SAM|25 muM Br(2) + 0.1 M Na(2)SO(4)|| 50 muM KBr + 0.1 M Na(2)SO(4)|Au. In the galvanic cell, the oxidant (Br(2)) is scavenged by a heterogeneous electron transfer reaction, slowing the reaction of D-OEG with Br(2). The slow progress of the reaction with Br(2) allowed us to draw conclusions about molecular rearrangements taking place during this reaction. The reaction with Br(2) starts on boundaries and/or defects present in the SAM. First, at the defect place, the alpha-C atom of the OEG chain reacts with Br(2) and the OEG part of the molecule is removed from the monolayer. In consequence an increase in disorder in the OEG part of the SAM is observed. The same mechanism of the reaction with Br(2) is applied for the d-dodecane alkanethiol part of the molecule. This reaction is slow, thus the order and the tilt of the hydrocarbon chain changes only a little during the reaction time.
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Affiliation(s)
- Izabella Brand
- Carl von Ossietzky University of Oldenburg, Center of Interface Science (CIS) and Department of Pure and Applied Chemistry, D-26111 Oldenburg, Germany.
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20
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Lee HH, Ruzele Z, Malysheva L, Onipko A, Gutés A, Björefors F, Valiokas R, Liedberg B. Long-chain alkylthiol assemblies containing buried in-plane stabilizing architectures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:13959-13971. [PMID: 19791763 DOI: 10.1021/la901668u] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A series of alkylthiol compounds were synthesized to study the formation and structure of complex self-assembled monolayers (SAMs) consisting of interchanging structural modules stabilized by intermolecular hydrogen bonds. The chemical structure of the synthesized compounds, HS(CH(2))(15)CONH(CH(2)CH(2)O)(6)CH(2)CONH-X, where X refers to the extended chains of either -(CH(2))(n)CH(3) or -(CD(2))(n)CD(3), with n = 0, 1, 7, 8, 15, was confirmed by NMR and elemental analysis. The formation of highly ordered, methyl-terminated SAMs on gold from diluted ethanolic solutions of these compounds was revealed using contact angle goniometry, null ellipsometry, cyclic voltammetry, and infrared reflection absorption spectroscopy. The experimental work was complemented with extensive DFT modeling of infrared spectra and molecular orientation. New assignments were introduced for both nondeuterated and deuterated compounds. The latter set of compounds also served as a convenient tool to resolve the packing, conformation, and orientation of the buried and extended modules within the SAM. Thus, it was shown that the lower alkyl portion together with the hexa(ethylene glycol) portion is stabilized by the two layers of lateral hydrogen bonding networks between the amide groups, and they provide a structurally robust support for the extended alkyls. The presented system can be considered to be an extension of the well-known alkyl SAM platform, enabling precise engineering of nanoscopic architectures on the length scale from a few to approximately 60 A for applications such as cell membrane mimetics, molecular nanolithography, and so forth.
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Affiliation(s)
- Hung-Hsun Lee
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden
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21
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Leitch J, Kunze J, Goddard JD, Schwan AL, Faragher RJ, Naumann R, Knoll W, Dutcher JR, Lipkowski J. In situ PM-IRRAS studies of an archaea analogue thiolipid assembled on a au(111) electrode surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:10354-10363. [PMID: 19499931 DOI: 10.1021/la900907d] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) has been applied to determine the conformation, orientation, and hydration of a monolayer of 2,3-di-O-phytanyl-sn-glycerol-1-tetraethylene glycol-dl-alpha-lipoic acid ester (DPTL) self-assembled at a gold electrode surface. This Archaea analogue thiolipid has been recently employed to build tethered lipid bilayers. By synthesizing DPT(d16)L, a DPTL molecule with a deuterium substituted tetraethylene glycol spacer, it was possible to differentiate the C-H stretch vibrations of the phytanyl chains from the tetraethylene glycol spacer and acquire the characteristic IR spectra for the chains, spacer, and lipoic acid headgroup separately. Our results show that the structure of the monolayer displays remarkable stability in a broad range of electrode potentials and that the phytanyl chains remain in a liquid crystalline state. The tetraethylene glycol chains are coiled, and the IR spectrum for this region shows that it is in the disordered state. The most significant result of this study is the information that in contrast to expectations the spacer region is poorly hydrated. Our results have implications for the design of a tethered lipid membrane based on this thiolipid.
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Affiliation(s)
- Jay Leitch
- Department of Chemistry, University of Guelph, Guelph, Ontario, N1G2W1 Canada
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22
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Wiecinski PN, Metz KM, Mangham AN, Jacobson KH, Hamers RJ, Pedersen JA. Gastrointestinal biodurability of engineered nanoparticles: Development of an in vitro assay. Nanotoxicology 2009; 3:202-214. [PMID: 25197315 PMCID: PMC4156289 DOI: 10.1080/17435390902859556] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The toxicity of engineered nanoparticles is expected to depend in part on their stability in biological systems. To assess the biodurability of engineered nanomaterials in the human digestive system, we adapted an in vitro assay previously used to evaluate the bioaccessibility of metals in contaminated soils. The compositions of the simulated gastric and intestinal fluids, temperature and residence times were designed to closely mimic conditions in the stomach and duodenum of the small intestine. We demonstrated the utility of the assay using CdSecore/ZnSshell quantum dots functionalized with polyethylene glycol (PEG) thiol of two different molecular masses (PEG350 and PEG5000). Under gastric conditions, removal of the PEG ligand diminished the stability of PEG350-quantum dot suspensions, while PEG5000-quantum dots were severely degraded. Inclusion of the glycoprotein mucin, but not the digestive protein pepsin, in simulated gastric fluids provided both PEG350- and PEG5000-coated quantum dots partial protection from transformations induced by gastric conditions.
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Affiliation(s)
- Paige N Wiecinski
- Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI, USA
| | - Kevin M Metz
- Environmental Chemistry and Technology Program, University of Wisconsin, Madison, WI, USA
| | - Andrew N Mangham
- Department of Chemistry, University of Wisconsin, Madison, WI, USA
| | - Kurt H Jacobson
- Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI, USA
| | - Robert J Hamers
- Department of Chemistry, University of Wisconsin, Madison, WI, USA
| | - Joel A Pedersen
- Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI, USA ; Environmental Chemistry and Technology Program, University of Wisconsin, Madison, WI, USA ; Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI, USA ; Department of Soil Science, University of Wisconsin, Madison, WI, USA
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23
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Devouge S, Conti J, Goldsztein A, Gosselin E, Brans A, Voué M, De Coninck J, Homblé F, Goormaghtigh E, Marchand-Brynaert J. Surface functionalization of germanium ATR devices for use in FTIR-biosensors. J Colloid Interface Sci 2008; 332:408-15. [PMID: 19150721 DOI: 10.1016/j.jcis.2008.12.045] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 12/01/2008] [Accepted: 12/17/2008] [Indexed: 11/25/2022]
Abstract
Biosensors based on intrinsic detection methods have attracted growing interest. The use of Fourier transform infra-red (FTIR) spectroscopy with the attenuated internal total reflection (ATR) mode, in the biodetection context, requires appropriate surface functionalization of the ATR optical element. Here, we report the direct grafting of a thin organic layer (about 20 A depth) on the surface of a germanium crystal. This covering, constructed with novel amphiphilic molecules 2b (namely, 2,5,8,11,14,17,20-heptaoxadocosan-22-yl-3-(triethoxysilyl) propylcarbamate), is stable for several hours under phosphate buffered saline (PBS) flux and features protein-repulsive properties. Photografting of molecule 5 (namely, O-succinimidyl 4-(p-azidophenyl)butanoate) affords the activated ATR element, ready for the covalent fixation of receptors, penicillin recognizing proteins BlaR-CTD for instance. The different steps of the previous construction have been monitored by water contact angle (theta(w)) measurements, spectroscopic ellipsometry (covering depth), X-ray photoelectron spectroscopy (XPS) by using a fluorinated tag for the control of surface reactivity, and FTIR-ATR spectroscopy for the structural analysis of grafted molecules. Indeed, contrarily to silicon device, germanium device offers a broad spectral window (1000-4000 cm(-1)) and thus amide I and II absorption bands can be recorded. This work lays the foundations for the construction of novel FTIR biosensors.
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Affiliation(s)
- Sabrina Devouge
- Unité de Chimie Organique et Médicinale, Université Catholique de Louvain, Bâtiment Lavoisier, Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
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24
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Zhao C, Zawisza I, Nullmeier M, Burchardt M, Träuble M, Witte I, Wittstock G. Microelectrochemical modulation of micropatterned cellular environments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:7605-7613. [PMID: 18547087 DOI: 10.1021/la8003432] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Patterned cell cultures obtained by microcontact printing have been modified in situ by a microelectrochemical technique. It relies on lifting cell-repellent properties of oligo(ethylene glycol)-terminated self-assembled monolayers (SAMs) by Br2, which is produced locally by an ultramicroelectrode of a scanning electrochemical microscope (SECM). After Br2 treatment the SAM shows increased permeability and terminal hydrophobicity as characterized by SECM approach curves and contact angle measurements, respectively. Polarization-modulation Fourier transform infrared reflection-absorption spectroscopic (PM FTIRRAS) studies on macroscopic samples show that the Br2 treatment removes the oligo(ethelyene glycol) part of the monolayer within a second time scale while the alkyl part of the SAM degrades with a much slower rate. The lateral extension of the modification can be limited because heterogeneous electron transfer from the gold support destroys part of the electrogenerated Br2 once the monolayer is locally damaged in a SECM feedback configuration. This effect has been reproduced and analyzed by exposing SAM-modified samples to Br2 in the galvanic cell Au|SAM|5 microM Br2 + 0.1 M Na2SO4||10 microM KBr + 0.1 M Na2SO4|Au followed by an PM FTIRRAS characterization of the changes in the monolayer system.
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Affiliation(s)
- Chuan Zhao
- Carl von Ossietzky University of Oldenburg, Faculty of Mathematics and Natural Sciences, Center of Interface Science, Institute of Pure and Applied Chemistry and Institute of Chemistry and Biology of the Marine Environment, D-26111 Oldenburg, Germany
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25
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Valiokas R, Klenkar G, Tinazli A, Reichel A, Tampé R, Piehler J, Liedberg B. Self-assembled monolayers containing terminal mono-, bis-, and tris-nitrilotriacetic acid groups: characterization and application. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:4959-4967. [PMID: 18393558 DOI: 10.1021/la703709a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We have undertaken a structural and functional study of self-assembled monolayers (SAMs) formed on gold from a series of alkylthiol compounds containing terminal multivalent chelators (MCHs) composed of mono-, bis-, and tris-nitrilotriacetic acid (NTA) moieties. SAMs were formed from single-component solutions of the mono-, bis-, and tris-NTA compounds, as well as from mixtures with a tri(ethylene glycol)-terminated alkylthiol (EG(3)). Contact angle goniometry, null ellipsometry, and infrared spectroscopy were used to explore the structural characteristics of the MCH SAMs. Ellipsometric measurements show that the amount of the MCH groups on surfaces increases with increasing mol % of the MCH thiols in the loading solution up to about 80 mol %. We also conclude that mixed SAMs, prepared in the solution composition regime 0-30 mol % of the MCH thiols, consist of a densely packed alkyl layer, an amorphous ethylene glycol layer, and an outermost layer of MCH groups exposed toward the ambient. Above 30 mol %, a significant degree of disorder is observed in the SAMs. Finally, functional evaluation of the three MCH SAMs prepared at 0-30 mol% reveals a consistent increase in binding strength with increasing multivalency. The tris-NTA SAM, in particular, is enabled for stable and functional immobilization of a His6-tagged extracellular receptor subunit, even at low chelator surface concentrations, which makes it suitable for applications when a low surface density of capturing sites is desirable, e.g., in kinetic analyses.
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Affiliation(s)
- Ramunas Valiokas
- Department of Functional Nanomaterials, Institute of Physics, Savanoriu; 231, LT-02300 Vilnius, Lithuania.
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26
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Malysheva L, Onipko A, Liedberg B. Ab Initio Modeling of Amide-Stabilized, Oligo(ethylene glycol)-Terminated Self-Assemblies: In-SAM Molecular Geometry, Orientation, and Hydrogen Bonding. J Phys Chem A 2008; 112:1683-7. [DOI: 10.1021/jp711604h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lyuba Malysheva
- Bogolyubov Institute for Theoretical Physics, 03680 Kyiv, Ukraine, and Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping, Sweden
| | - Alexander Onipko
- Bogolyubov Institute for Theoretical Physics, 03680 Kyiv, Ukraine, and Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping, Sweden
| | - Bo Liedberg
- Bogolyubov Institute for Theoretical Physics, 03680 Kyiv, Ukraine, and Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping, Sweden
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27
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Malysheva L, Onipko A, Liedberg B. Ab Initio Modeling of Defect Signatures in Infrared Reflection−Absorption Spectra of SAMs Exposing Methyl- and Hydrogen-Terminated Oligo(ethylene glycols). J Phys Chem A 2008; 112:728-36. [DOI: 10.1021/jp075586r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lyuba Malysheva
- Bogolyubov Institute for Theoretical Physics, 03680 Kyiv, Ukraine, and Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping, Sweden
| | - Alexander Onipko
- Bogolyubov Institute for Theoretical Physics, 03680 Kyiv, Ukraine, and Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping, Sweden
| | - Bo Liedberg
- Bogolyubov Institute for Theoretical Physics, 03680 Kyiv, Ukraine, and Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, S-581 83 Linköping, Sweden
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28
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Shin HS, Kim JH, Kim SB, Jung YM. Thermal characterization of self-assembled monolayers of dialkyl disulfides containing the urea moiety. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:10567-72. [PMID: 17803328 DOI: 10.1021/la7015947] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Thermal behaviors of urea-containing dialkyl disulfides 4-(3-octadecylureido)phenyl disulfide (ODPD) and 3-(octadecylureido)ethane disulfide (ODED) and octadecyl disulfide (ODDS) self-assembled monolayers (SAMs) were investigated by infrared reflection-absorption spectroscopy (IRRAS). Among the SAMs, the alkyl chain of ODPD is thermally reversible in the temperature region between 30 and 138 degrees C, whereas alkyl chains of ODED and ODDS are irreversible. With regard to the thermal stability of alkyl chains, ODED is superior to ODPD and ODDS. It is considered that the good thermal reversibility of the ODPD SAM is due to the rigid phenyl ring and the good thermal stability of the ODED SAM is due to the flexible ethylene linker. Moreover, 2D correlation analysis provides an enhancement of spectral resolution in amide II and CH2 antisymmetric stretching bands and suggests from the comparison of sequences of spectral events of ODPD and ODED SAMs that the last reorientation of the phenyl ring in the ODPD SAM is responsible for the good thermal reversibility.
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Affiliation(s)
- Hyeon Suk Shin
- Department of Chemistry, Pohang University of Science & Technology, Pohang 790-784, Republic of Korea.
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29
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Gnauck M, Jaehne E, Blaettler T, Tosatti S, Textor M, Adler HJP. Carboxy-terminated oligo(ethylene glycol)-alkane phosphate: synthesis and self-assembly on titanium oxide surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:377-81. [PMID: 17209580 DOI: 10.1021/la0606648] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The surface immobilization of oligo- and poly(ethylene glycol) on solids is a widely used approach to prevent the nonspecific adsorption of proteins, bacteria, and cells. A novel tri(ethylene glycol) derivative, phosphoric acid-mono(22-carboxy-12,15,18,21-tetraoxadocosyl) ester, was synthesized with the aim to produce self-assembled monolayers (SAMs) on metal/metal oxide surfaces. This compound contains two reactive, terminal moieties: the phosphoric acid group as anchor to the surface, and the carboxylic group as linker for further attachment of molecules such as peptides and proteins to be present at the surface. The adsorption on titanium-dioxide-coated substrates was studied quantitatively and the resulting SAMs were characterized by angle-dependent X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry. XPS data showed that the monomolecular layer is attached with the phosphate group to the substrate, but not fully ordered. The dry adlayer thickness was determined to be 13.4 A, which is less than expected for a densely packed monolayer. Surface concentration calculated from ellipsometry data resulted in a grafting density of 2.03 molecules/nm2.
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Affiliation(s)
- Mandy Gnauck
- Institute for Macromolecular Chemistry and Textile Chemistry, Department of Chemistry and Food Chemistry, Faculty of Science, Technische Universität Dresden, Dresden, Germany
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30
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Zoulalian V, Monge S, Zürcher S, Textor M, Robin JJ, Tosatti S. Functionalization of Titanium Oxide Surfaces by Means of Poly(alkyl-phosphonates). J Phys Chem B 2006; 110:25603-5. [PMID: 17181194 DOI: 10.1021/jp066811s] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The use of a multiple attachment sites strategy is considered in order to improve the stability of monomolecular adlayers. The hypothesis was tested in the case of PEG-ylated compounds carrying phosphonate groups, known for their affinity toward titanium oxide surfaces. As a result, a new class of co- and terpolymers were synthesized by free-radical polymerization of three different monomers: dialkyl(methacryloyloxyalkyl)phosphonates, PEG methyl ether methacrylate, and/or butyl methacrylate monomers. Adlayers were formed following a simple dip-and-rinse protocol using diluted aqueous polymer solutions and were characterized by evaluating their thicknesses with variable angle spectroscopic ellipsometry (VASE) and their elemental compositions with X-ray photoelectron spectroscopy (XPS). The same techniques were used to determine changes of the adlayer as a function of exposure to electrolytes at different pH values and to monitor nonspecific protein adsorption upon serum exposures. The results indicated that the poly(alkyl-phosphonate)-based adlayers combine multiple site attachment of phosphonic groups and presentation of PEG side chains to the aqueous environment, resulting in both improved stability over a wide pH range in comparison to the tested reference surfaces and excellent resistance to protein adsorption when exposed to full human serum.
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Affiliation(s)
- V Zoulalian
- Laboratory for Surface Science and Technology, ETH Zurich, CH-8093 Zurich, Switzerland
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31
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Blomberg E, Claesson PM, Konradsson P, Liedberg B. Globotriose- and oligo(ethylene glycol)-terminated self-assembled monolayers: surface forces, wetting, and surfactant adsorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:10038-46. [PMID: 17106997 DOI: 10.1021/la061857y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A set of oligo(ethylene glycol)-terminated and globotriose-terminated self-assembled monolayers (SAMs) has been prepared on gold substrates. Such model surfaces are well defined and have good stability due to the strong binding of thiols and disulfides to the gold substrate. They are thus very suitable for addressing questions related to effects of surface composition on wetting properties, surface interactions, and surfactant adsorption. These issues are addressed in this report. Accurate wetting tension measurements have been performed as a function of temperature using the Wilhelmy plate technique. The results show that the nonpolar character of oligo(ethylene glycol)-terminated SAMs increases slightly but significantly with temperature in the range 20-55 degrees C. On the other hand, globotriose-terminated SAMs are fully wetted by water at room temperature. Surface forces measurements have been performed and demonstrated that the interactions between oligo(ethylene glycol)-terminated SAMs are purely repulsive and similar to those determined between adsorbed surfactant layers with the same terminal headgroup. On the other hand, the interactions between globotriose-terminated SAMs include a short-range attractive force component that is strongly affected by the packing density in the layer. In some cases it is found that the attractive force component increases with contact time. Both these observations are rationalized by an orientation- and conformation-dependent interaction between globotriose headgroups, and it is suggested that hydrogen-bond formation, directly or via bridging water molecules, is the molecular origin of these effects.
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Affiliation(s)
- Eva Blomberg
- Department of Chemistry, Surface Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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32
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Hunks WJ, Jennings MC, Puddephatt RJ. Polymeric and macrocyclic gold(I) complexes with bridging dithiolate and diphosphine ligands. Inorganica Chim Acta 2006. [DOI: 10.1016/j.ica.2006.01.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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33
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Tinazli A, Tang J, Valiokas R, Picuric S, Lata S, Piehler J, Liedberg B, Tampé R. High-affinity chelator thiols for switchable and oriented immobilization of histidine-tagged proteins: a generic platform for protein chip technologies. Chemistry 2006; 11:5249-59. [PMID: 15991207 DOI: 10.1002/chem.200500154] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Protein micro-/nanoarrays are becoming increasingly important in systematic approaches for the exploration of protein-protein interactions and dynamic protein networks, so there is a high demand for specific, generic, stable, uniform, and locally addressable protein immobilization on solid supports. Here we present multivalent metal-chelating thiols that are suitable for stable binding of histidine-tagged proteins on biocompatible self-assembled monolayers (SAMs). The architectures and physicochemical properties of these SAMs have been probed by various surface-sensitive techniques such as contact angle goniometry, ellipsometry, and infrared reflection-absorption spectroscopy. The specific molecular organization of proteins and protein complexes was demonstrated by surface plasmon resonance, confocal laser scanning, and atomic force microscopy. In contrast to the mono-NTA/His6 tag interaction, which has major drawbacks because of its low affinity and fast dissociation, drastically improved stability of protein binding by these multivalent chelator surfaces was observed. The immobilized histidine-tagged proteins are uniformly oriented and retain their function. At the same time, proteins can be removed from the chip surface under mild conditions (switchability). This new platform for switchable and oriented immobilization should assist proteome-wide wide analyses of protein-protein interactions as well as structural and single-molecule studies.
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Affiliation(s)
- Ali Tinazli
- Institute of Biochemistry, Biocenter, Johann Wolfgang Goethe-University, Marie-Curie-Strasse 9, 60439 Frankfurt, Germany
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34
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Suo Z, Arce FT, Avci R, Thieltges K, Spangler B. Dendritic structures of poly(ethylene glycol) on silicon nitride and gold surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:3844-50. [PMID: 16584265 DOI: 10.1021/la053389i] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A hydrophilic silicon nitride surface was grafted with poly(ethylene glycol) monomethyl ether (average formula weight of 5000 Da) in a one-step protocol. The domains of stable dendritic structures of self-assembled monolayer islands on a silicon nitride surface were observed with atomic force microscopy. The moduli of elasticity of these dendritic structures in air and in KCl aqueous solution were compared. The value of the Young's modulus of these structures is reduced by more than 3 orders of magnitude, from approximately 12 GPa measured in air to approximately 5 MPa in KCl solution. This dramatic reduction in elasticity was attributed to the swelling of the dendritic structures in aqueous solution, which was verified by the increased film thickness. These dendritic structures were not stable in the aqueous environment and could be removed by soaking in water for 22 h because of the hydrolysis of the silicate bonds. This fact was confirmed by the reduction of the C1s signal in the X-ray photoelectron spectroscopy experiments. These morphologies are not unique to silicon nitride substrate; similar features were also observed for thiolated poly(ethylene glycol) monomethyl ether molecules absorbed on a gold surface.
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Affiliation(s)
- Zhiyong Suo
- Image and Chemical Analysis Laboratory, Physics Department, Montana State University, Bozeman, Montana 59717, USA
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35
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Structural and kinetic properties of laterally stabilized, oligo(ethylene glycol)-containing alkylthiolates on gold: A modular approach. Biointerphases 2006; 1:22. [DOI: 10.1116/1.2188521] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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36
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Saalmink M, van der Marel C, Stapert HR, Burdinski D. Positive microcontact printing with mercaptoalkyloligo(ethylene glycol)s. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:1016-26. [PMID: 16430261 DOI: 10.1021/la052513v] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The soft lithographic replication of patterns with a low filling ratio by microcontact printing (microCP) is problematic due to the poor mechanical stability of common elastomeric stamps. A recently described strategy to avoid this problem employs a modified patterning method, positive microcontact printing ((+)microCP), in which a stamp with a mechanically more stable inverted relief pattern is used. In contrast to conventional negative microCP ((-)microCP), in the contact areas a self-assembled monolayer (SAM) is printed of a "positive ink", which provides only minor etch protection, whereas the noncontacted areas are subsequently covered with a different, etch-resistant SAM, prior to development by chemical etching. With the aim to identify novel, highly versatile positive inks, the patterning of gold by (+)microCP with mercaptoalkyloligo(ethylene glycol)s (MAOEGs), the subsequent adsorption of octadecanethiol (ODT), and the final development by wet chemical etching have now been studied. A polydisperse mixture of mercaptoundecylocta(ethylene glycol) derivatives was found to provide the best patterning results. The surface spreading of the positive ink during stamping, the exchange of printed MAOEGs with ODT, and the choice of the right etching bath were identified as key parameters that influence the achievable pattern resolution and contrast. Due to the modular composition of functionalized alkyloligo(ethylene glycol) derivatives, (+)microCP with these positive inks has the potential for easy adaptation to a variety of materials and development conditions.
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Affiliation(s)
- Milan Saalmink
- Philips Research, High Tech Campus Eindhoven, 5656 AE Eindhoven, The Netherlands
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37
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Ostblom M, Valiokas R, Konradsson P, Svensson SCT, Liedberg B, Garrett M, Allara DL. Ice Nucleation and Phase Behavior on Oligo(ethylene glycol) and Hydroxyl Self-Assembled Monolayers: Simulations and Experiments. J Phys Chem B 2006; 110:1830-6. [PMID: 16471752 DOI: 10.1021/jp056007q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nucleation and phase behavior of ultrathin D2O-ice overlayers have been studied on oligo(ethylene glycol) (OEG)-terminated and hydroxyl self-assembled monolayers (SAMs) at low temperatures in ultrahigh vacuum. Infrared reflection-absorption spectroscopy (IRAS) is used to characterize the ice overlayers, the SAMs, and the interactions occurring between the ice and the SAM surfaces. Spectral simulations, based on optical models in conjunction with Maxwell Garnett effective medium theory, point out the importance of including voids in the modeling of the ice structures, with void fractions reaching 60% in some overlayers. The kinetics of the phase transition from amorphous-like to crystalline-like ice upon isothermal annealing at 140 K is found to depend on the conformational state of the supporting OEG SAM surface. The rate is fast on the helical OEG SAMs and slow on the corresponding all-trans SAMs. This difference in kinetics is most likely due to a pronounced D2O interpenetration and binding to the all-trans segments of the ethylene glycol portion of the SAM. No such penetration and binding was observed on the helical OEG SAM.
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Affiliation(s)
- Mattias Ostblom
- Division of Molecular Physics, Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden
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38
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Fabris L, Antonello S, Armelao L, Donkers RL, Polo F, Toniolo C, Maran F. Gold Nanoclusters Protected by Conformationally Constrained Peptides. J Am Chem Soc 2005; 128:326-36. [PMID: 16390162 DOI: 10.1021/ja0560581] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The preparation and properties of a series of gold nanoclusters protected by thiolated peptides based on the alpha-aminoisobutyric acid (Aib) unit are described. The peptides were devised to form 0-3 C=O...H-N intramolecular hydrogen bonds, as required by their 3(10)-helical structure. The monolayer-protected clusters (MPCs) were prepared, using a modified version of the two-phase Brust-Schiffrin preparation, and fully characterized with (1)H NMR spectrometry, IR and UV-vis absorption spectroscopies, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The MPCs were obtained with core diameters in the range of 1.1-2.3 nm, depending on the reaction conditions. Structured peptides formed smaller clusters. The smallest MPC obtained is in agreement with the average formula Au(38)Pep(18). The results showed that the chemical integrity of the peptide is maintained upon monolayer formation and that the average number of peptide ligands per gold cluster is typically 75-85% the value calculated for alkanethiolate MPCs of similar sizes. The IR and NMR spectra indicated that in the monolayer the peptides are involved in both intra- and interligand C=O...H-N hydrogen bonds.
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Affiliation(s)
- Laura Fabris
- Department of Chemistry, University of Padua, via Marzolo 1, 35131 Padua, Italy
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39
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A convenient synthesis of long-chain 4-substituted benzyloxycarbonyl alkanethiols for the formation of self assembled monolayers on metal substrates. OPEN CHEM 2005. [DOI: 10.2478/bf02475194] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractNew 4-substituted benzyl esters of 16-mercaptohexadecanoic acid were prepared by developing a practicable synthetic procedure and using readily available staring materials. The compounds synthesized have been characterized by NMR, MS, IR spectra and elemental analysis. The mercapto derivatives are precursors for the formation of self-assembled monolayers on metal substrates.
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40
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Malysheva L, Onipko A, Valiokas R, Liedberg B. Molecular Orientation in Helical and All-Trans Oligo(ethylene glycol)-Terminated Assemblies on Gold: Results of ab Initio Modeling. J Phys Chem A 2005; 109:7788-96. [PMID: 16834156 DOI: 10.1021/jp052395k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The structural properties of self-assembled monolayers (SAMs) of oligo(ethylene glycol) (OEG)-terminated and amide-containing alkanethiols (HS(CH(2))(15)CONH(CH(2)CH(2)O)(6)H and related molecules with shorter alkyl or OEG portions) on gold are addressed. Optimized geometry of the molecular constituents, characteristic vibration frequencies, and transition dipole moments are obtained using density-functional theory methods with gradient corrections. These data are used to simulate IR reflection-absorption (RA) spectra associated with different OEG conformations. It is shown that the positions and relative intensities of all characteristic peaks in the fingerprint region are accurately reproduced by the model spectra within a narrow range of the tilt and rotation angles of the alkyl plane, which turns out to be nearly the same for the helical and all-trans OEG conformations. In contrast, the tilt of the OEG axis changes considerably under conformational transition from helical to all-trans OEG. By means of ab initio modeling, we also clarify other details of the molecular structure and orientation, including lateral hydrogen bonding, the latter of which is readily possessed by the SAMs in focus. These results are crucial for understanding phase and folding characteristics of OEG SAMs and other complex molecular assemblies. They are also expected to contribute to an improved understanding of the interaction with water, ions, and ultimately biological macromolecules.
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Affiliation(s)
- L Malysheva
- Bogolyubov Institute for Theoretical Physics, Kiev, 03143, Ukraine
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41
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Malysheva L, Onipko A, Valiokas R, Liedberg B. First-Principle DFT and MP2 Modeling of Infrared Reflection−Absorption Spectra of Oriented Helical Ethylene Glycol Oligomers. J Phys Chem B 2005; 109:13221-7. [PMID: 16852649 DOI: 10.1021/jp0503765] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
First-principle modeling is used to obtain a comprehensive understanding of infrared reflection absorption (RA) spectra of helical oligo(ethylene glycol) (OEG) containing self-assembled monolayers (SAMs). Highly ordered SAMs of methyl-terminated 1-thiaoligo(ethylene glycols) [HS(CH2CH2O)(n)CH3, n = 5, 6] on gold recently became accessible for systematic infrared analyses [Vanderah et al., Langmuir, 2003, 19, 3752]. We utilized the quoted experimental data to validate the first-principle modeling of infrared RA spectra of HS(CH2CH2O)(5,6)CH3 obtained by (i) DFT methods with gradient corrections (using different basis sets, including 6-311++G) and (ii) HF method followed by a Møller-Plesset (MP2) correlation energy correction. In focus are fundamental modes in the fingerprint and CH-stretching regions. The frequencies and relative intensities in the calculated spectra for a single molecule are unambiguously identified with the bands observed in the experimental RA spectra of the corresponding SAMs. In addition to confirming our earlier assignment of the dominating peak in the CH-stretching region to CH2 asymmetric stretching vibrations, all other spectral features observed in that region have received an interpretation consistent (but not in all cases coinciding) with previous investigations. The obtained results provide an improved understanding of the orientation and conformation of the molecular building blocks within OEG-containing assemblies, which, in our opinion, is crucial for being able to predict the folding and phase characteristics and interaction of OEG-SAMs with water and proteins.
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Affiliation(s)
- Lyuba Malysheva
- Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine, Division of Physics, Luleå University of Technology, S-971 87 Luleå, Sweden
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42
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Love JC, Estroff LA, Kriebel JK, Nuzzo RG, Whitesides GM. Self-Assembled Monolayers of Thiolates on Metals as a Form of Nanotechnology. Chem Rev 2005; 105:1103-69. [PMID: 15826011 DOI: 10.1021/cr0300789] [Citation(s) in RCA: 4698] [Impact Index Per Article: 247.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- J Christopher Love
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA
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43
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Riepl M, Ostblom M, Lundström I, Svensson SCT, Denier van der Gon AW, Schäferling M, Liedberg B. Molecular gradients: an efficient approach for optimizing the surface properties of biomaterials and biochips. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:1042-1050. [PMID: 15667187 DOI: 10.1021/la048358m] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A variety of molecular gradients of alkanethiols with the structure HS-(CH(2))(m)-X (m = 15; X = COOH, CH(2)NH(2), or CH(3)) and oligo(ethylene glycol)-terminated alkanethiols with the structures HS-(CH(2))(15)-CO-NH-Eg(n) (n = 2, 4, or 6), HS-(CH(2))(15)-CO-NH-Eg(2)-(CH(2))(2)-NH-CO-(CH(2))(4)-biotin, and HS-(CH(2))(15)-CO-NH-Eg(6)-CH(2)-COOH were prepared on polycrystalline gold films. These gradients were designed to serve as model surfaces for fundamental studies of protein adsorption and immobilization phenomena. Ellipsometry, infrared spectroscopy, and X-ray photoelectron spectroscopy, operating in scanning mode, were used to monitor the layer composition, gradient profiles, tail group conformation, and overall structural quality of the gradient assemblies. The gradient profiles were found to be 4-10 mm wide, and they increased in width with increasing difference in molecular complexity between the thiols used to form the gradient. The oligo(ethylene glycol) thiols are particularly interesting because they can be used to prepare so-called conformational gradients, that is, gradients that display a variation in oligo(ethylene glycol) chain conformation from all trans on the extreme Eg(2,4) sides, via an amorphous-like phase in the mixing regimes, to helical at the extreme Eg(6) sides. We demonstrate herein a series of experiments where the above gradients are used to evaluate nonspecific binding of the plasma protein fibrinogen, and in agreement with previous studies, the highest amounts of nonspecifically bound fibrinogen were observed on all-trans monolayers, that is, on the extreme Eg(2,4) sides. Moreover, gradients between Eg(2) and a biotinylated analogue have been prepared to optimize the conditions for the immobilization of streptavidin. Ellipsometry and infrared spectroscopy reveal high levels of immobilization over a fairly broad range of compositions in the gradient regime, with a maximum between 50 and 60% of the biotinylated analogue in the monolayer. A pI gradient composed of (NH(3)(+)/COO(-))-terminated thiols was also prepared and evaluated with respect to its ability to separate differently charged proteins, pepsin, and lysozyme, on a solid surface.
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Affiliation(s)
- Michael Riepl
- Division of Sensor Science and Molecular Physics, Department of Physics and Measurement Technology, Linköping University, SE-58183 Linköping, Sweden
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44
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Zhou Y, Valiokas R, Liedberg B. Structural characterization of microcontact printed arrays of hexa(ethylene glycol)-terminated alkanethiols on gold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:6206-15. [PMID: 15248704 DOI: 10.1021/la049421a] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This paper reports on the structural characteristics of microcontact printed oligo(ethylene glycol)-terminated alkanethiol layers, HS(CH2)15CONH-(CH2CH2O)6-H (hereafter EG6), on gold. Microwetting, contact angle goniometry, imaging null ellipsometry, and infrared reflection-absorption spectroscopy (IRAS) are used to characterize the printed EG6 layers, and the quality of these layers in terms of layer thickness and the crystallinity of the alkyl and ethylene glycol portions is compared with data obtained from analogous layers prepared by solution self-assembly. The outcome of the printing process is critically dependent on the experimental parameters used to prepare the patterns. It is found that high quality layers, consisting of densely packed all-trans alkyl chains terminated with relatively helical hexa(ethylene glycol) tails, are formed by inking the poly(dimethylsiloxane) (PDMS) stamp with a 1 mM EG6 solution and contacting it with gold for 15 min. The homogeneity of printed layers is not as good as the homogeneity of those prepared from solution under similar conditions, most likely because of simultaneous transfer of low molecular weight residues from the PDMS stamp. These residues, however, can be easily removed upon ultrasonication in ethanol without affecting the quality of the printed layer. Further on, the microscopic square-shaped bare gold patterns formed after microcontact printing (muCP) are subsequently filled with 16-hexadecanoic acid (hereafter THA) or HS(CH2)15CONH-(CH2CH2O)6-COOH (hereafter EG6COOH) to provide a microarray platform for further covalent attachment of biomolecules. Well-defined structures in terms of wettability contrast, sharpness, and height differences between the printed and back-filled areas are confirmed by imaging null ellipsometry and microscopic wetting.
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Affiliation(s)
- Ye Zhou
- S-SENCE and Division of Sensor Science and Molecular Physics, Linköping University, S-581 83 Linköping, Sweden
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45
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Valentine MT, Perlman ZE, Gardel ML, Shin JH, Matsudaira P, Mitchison TJ, Weitz DA. Colloid surface chemistry critically affects multiple particle tracking measurements of biomaterials. Biophys J 2004; 86:4004-14. [PMID: 15189896 PMCID: PMC1304301 DOI: 10.1529/biophysj.103.037812] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2003] [Accepted: 02/23/2004] [Indexed: 11/18/2022] Open
Abstract
Characterization of the properties of complex biomaterials using microrheological techniques has the promise of providing fundamental insights into their biomechanical functions; however, precise interpretations of such measurements are hindered by inadequate characterization of the interactions between tracers and the networks they probe. We here show that colloid surface chemistry can profoundly affect multiple particle tracking measurements of networks of fibrin, entangled F-actin solutions, and networks of cross-linked F-actin. We present a simple protocol to render the surface of colloidal probe particles protein-resistant by grafting short amine-terminated methoxy-poly(ethylene glycol) to the surface of carboxylated microspheres. We demonstrate that these poly(ethylene glycol)-coated tracers adsorb significantly less protein than particles coated with bovine serum albumin or unmodified probe particles. We establish that varying particle surface chemistry selectively tunes the sensitivity of the particles to different physical properties of their microenvironments. Specifically, particles that are weakly bound to a heterogeneous network are sensitive to changes in network stiffness, whereas protein-resistant tracers measure changes in the viscosity of the fluid and in the network microstructure. We demonstrate experimentally that two-particle microrheology analysis significantly reduces differences arising from tracer surface chemistry, indicating that modifications of network properties near the particle do not introduce large-scale heterogeneities. Our results establish that controlling colloid-protein interactions is crucial to the successful application of multiple particle tracking techniques to reconstituted protein networks, cytoplasm, and cells.
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Affiliation(s)
- M T Valentine
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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46
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Herrwerth S, Eck W, Reinhardt S, Grunze M. Factors that determine the protein resistance of oligoether self-assembled monolayers --internal hydrophilicity, terminal hydrophilicity, and lateral packing density. J Am Chem Soc 2003; 125:9359-66. [PMID: 12889964 DOI: 10.1021/ja034820y] [Citation(s) in RCA: 486] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein resistance of oligoether self-assembled monolayers (SAMs) on gold and silver surfaces has been investigated systematically to elucidate structural factors that determine whether a SAM will be able to resist protein adsorption. Oligo(ethylene glycol) (OEG)-, oligo(propylene glycol)-, and oligo(trimethylene glycol)-terminated alkanethiols with different chain lengths and alkyl termination were synthesized as monolayer constituents. The packing density and chemical composition of the SAMs were examined by XPS spectroscopy; the terminal hydrophilicity was characterized by contact angle measurements. IRRAS spectroscopy gave information about the chain conformation of specific monolayers; the amount of adsorbed protein as compared to alkanethiol monolayers was determined by ellipsometry. We found several factors that in combination or by themselves suppress the protein resistance of oligoether monolayers. Monolayers with a hydrophobic interior, such as those containing oligo(propylene glycol), show no protein resistance. The lateral compression of oligo(ethylene glycol) monolayers on silver generates more highly ordered monolayers and may cause decreased protein resistance, but does not necessarily lead to an all-trans chain conformation of the OEG moieties. Water contact angles higher than 70 degrees on gold or 65 degrees on silver reduce full protein resistance. We conclude that both internal and terminal hydrophilicity favor the protein resistance of an oligoether monolayer. It is suggested that the penetration of water molecules in the interior of the SAM is a necessary prerequisite for protein resistance. We discuss and summarize the various factors which are critical for the functionality of "inert" organic films.
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Affiliation(s)
- Sascha Herrwerth
- Angewandte Physikalische Chemie, Universität Heidelberg, INF 253, D 69120 Heidelberg, Germany
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47
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Malysheva L, Klymenko Y, Onipko A, Valiokas R, Liedberg B. Ab initio calculations of equilibrium geometries and vibrational excitations of helical ethylene-glycol oligomers: application to modeling of monolayer infrared spectra. Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(03)00116-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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48
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Valiokas R, Östblom M, Svedhem S, Svensson SCT, Liedberg B. Thermal Stability of Self-Assembled Monolayers: Influence of Lateral Hydrogen Bonding. J Phys Chem B 2002. [DOI: 10.1021/jp0200526] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ramūnas Valiokas
- Division of Applied Physics and Division of Chemistry, Department of Physics and Measurement Technology, Linköpings universitet, S-581 83 Linköping, Sweden
| | - Mattias Östblom
- Division of Applied Physics and Division of Chemistry, Department of Physics and Measurement Technology, Linköpings universitet, S-581 83 Linköping, Sweden
| | - Sofia Svedhem
- Division of Applied Physics and Division of Chemistry, Department of Physics and Measurement Technology, Linköpings universitet, S-581 83 Linköping, Sweden
| | - Stefan C. T. Svensson
- Division of Applied Physics and Division of Chemistry, Department of Physics and Measurement Technology, Linköpings universitet, S-581 83 Linköping, Sweden
| | - Bo Liedberg
- Division of Applied Physics and Division of Chemistry, Department of Physics and Measurement Technology, Linköpings universitet, S-581 83 Linköping, Sweden
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