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  • 1.
    Ericsson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Biosensor surface chemistry for oriented protein immobilization and biochip patterning2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis is focused on two methods for protein immobilization to biosensor surfaces for future applications in protein microarray formats. The common denominator is a surface chemistry based on a gold substrate with a self-assembled monolayer (SAM) of functionalized alkanethiolates. Both methods involve photochemistry, in the first case for direct immobilization of proteins to the surface, in the other for grafting a hydrogel, which is then used for protein immobilization.

    Paper I describes the development and characterization of Chelation Assisted Photoimmobilization (CAP), a three-component surface chemistry that allows for covalent attachment and controlled orientation of the immobilized recognition molecule (ligand) and thereby provides a robust sensor surface for detection of analyte in solution. The concept was demonstrated using His-tagged IgG-Fc as the ligand and protein A as the analyte. Surprisingly, as concluded from IR spectroscopy and surface plasmon resonance (SPR) analysis, the binding ability of this bivalent ligand was found to be more than two times higher with random orientation obtained by amine coupling than with homogeneous orientation obtained by CAP. It is suggested that a multivalent ligand is less sensitive to orientation effects than a monovalent ligand and that island formation of the alkanethiolates used for CAP results in a locally high ligand density and steric hindrance.

    Paper II describes the development of nanoscale hydrogel structures. These were photografted on a SAM pattern obtained by dip-pen nanolithography (DPN) and subsequent backfilling. The hydrogel grew fast on the hydrophilic patterns and slower on the hydrophobic background, which contained a buried oligo(ethylene glycol) (OEG) chain. Using IR spectroscopy, it was found that the OEG part was degraded during UV light irradiation and acted as a sacrificial layer. In this process other OEG residues were exposed and acted as new starting points for the self-initiated photografting and photopolymerization (SIPGP). A biotin derivative was immobilized to the hydrogel density pattern and interaction with streptavidin was demonstrated by epifluorescence microscopy.

    List of papers
    1. Controlled Orientation and Covalent Attachment of Proteins on Biosensor Surfaces by Chelation Assisted Photoimmobilization
    Open this publication in new window or tab >>Controlled Orientation and Covalent Attachment of Proteins on Biosensor Surfaces by Chelation Assisted Photoimmobilization
    Show others...
    2013 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This report presents a novel method for uniform orientation and covalent attachment of proteins to sensing surfaces, termed Chelation Assisted Photoimmobilization (CAP). Alkanethiols terminated with either nitrilotriacetic acid (NTA), benzophenone (BP) or oligo(ethylene glycol) were synthesized and mixed self-assembled monolayers (SAMs) were prepared on gold and thoroughly characterized by infrared reflection absorption spectroscopy (IRAS), ellipsometry and contact angle goniometry. In the process of CAP, NTA chelates Ni2+ and the complex coordinates a His-tagged ligand in an oriented assembly. The ligand is then photoimmobilized via BP, which forms covalent bonds upon UV light activation. The CAP concept was demonstrated using human IgG-Fc modified with C-terminal hexahistidine tags (His-IgGFc) as the ligand and protein A as the analyte.

    In the development of affinity biosensors, uniform orientation of ligand molecules where all analyte binding sites are accessible is often preferred to random orientation. In order to monitor the effect of ligand orientation on analyte response, the ligand-analyte interaction was quantified by surface plasmon resonance analysis, both in the case of CAP and when the ligand was attached by conventional amine coupling on surfaces presenting NTA. Responses were adjusted for differences in ligand immobilization level using IRAS. The normalized analyte response with randomly oriented ligand was 2.5 times higher than that with ligand immobilized by CAP, probably due to molecular crowding effects on the surface and the fact that His-IgGFc is bivalent for protein A. This is a reminder that many other factors than orientation alone may play a decisive role in analyte binding on biosensor surfaces.

    Keywords
    Biosensor, Surface chemistry, Protein immobilization, Orientation
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-87929 (URN)
    Available from: 2013-01-29 Created: 2013-01-28 Last updated: 2013-01-31
    2. Functional Hydrogel Density Patterns Fabricated by Dip-Pen Nanolithography and Photografting
    Open this publication in new window or tab >>Functional Hydrogel Density Patterns Fabricated by Dip-Pen Nanolithography and Photografting
    Show others...
    2011 (English)In: SMALL, ISSN 1613-6810, Vol. 7, no 15, p. 2153-2157Article in journal (Refereed) Published
    Abstract [en]

    n/a

    Place, publisher, year, edition, pages
    Wiley-VCH Verlag Berlin, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-70751 (URN)10.1002/smll.201002278 (DOI)000294361200003 ()
    Note

    |

    Available from: 2011-09-16 Created: 2011-09-16 Last updated: 2015-05-29
  • 2.
    Ericsson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Bui, Lan
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Oriented Protein Immobilization by Chelate Associated PhotochemistryManuscript (preprint) (Other academic)
    Abstract [en]

    We demonstrate herein the synthesis, characterization and application of a novel chelateassociated photochemistry (CAP) for oriented and robust attachment of biomolecular ligandsto sensing surfaces. The chelation agent is nitrilotriacetic acid (NTA) which is capable ofcoordinating two histidine (His) molecules in the presence of Nickel. Therefore a ligandmodified with a His-sequence can be attached to NTA to form an oriented assembly ofligands on the sensor surface. The ligand is then covalently bound to the surface via a nearbyphotolabile benzophenone (BP) which attacks C-H bonds upon UV light activation. Theligand is then available for analyte interaction. The synthesized compounds used in this studyare based on the well-known organosulphur surface chemistry for proper attachment to goldsurfaces. Besides the two BP and NTA alkane thiols/disulphides we also synthesized a fillermolecule with an oligo (ethylene glycol) (OEG) tail to fine tune the surface composition andto reduce non-specific binding. Results from surface plasmon resonance (SPR) measurementsusing a Biacore 3000 instrument indicate that up to 55% larger analyte response is obtainedwith CAP as compared to the response obtained with the random orientation achieved byphotoimmobilization alone.

  • 3.
    Ericsson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Bui, Lan
    Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Controlled Orientation and Covalent Attachment of Proteins on Biosensor Surfaces by Chelation Assisted Photoimmobilization2013Manuscript (preprint) (Other academic)
    Abstract [en]

    This report presents a novel method for uniform orientation and covalent attachment of proteins to sensing surfaces, termed Chelation Assisted Photoimmobilization (CAP). Alkanethiols terminated with either nitrilotriacetic acid (NTA), benzophenone (BP) or oligo(ethylene glycol) were synthesized and mixed self-assembled monolayers (SAMs) were prepared on gold and thoroughly characterized by infrared reflection absorption spectroscopy (IRAS), ellipsometry and contact angle goniometry. In the process of CAP, NTA chelates Ni2+ and the complex coordinates a His-tagged ligand in an oriented assembly. The ligand is then photoimmobilized via BP, which forms covalent bonds upon UV light activation. The CAP concept was demonstrated using human IgG-Fc modified with C-terminal hexahistidine tags (His-IgGFc) as the ligand and protein A as the analyte.

    In the development of affinity biosensors, uniform orientation of ligand molecules where all analyte binding sites are accessible is often preferred to random orientation. In order to monitor the effect of ligand orientation on analyte response, the ligand-analyte interaction was quantified by surface plasmon resonance analysis, both in the case of CAP and when the ligand was attached by conventional amine coupling on surfaces presenting NTA. Responses were adjusted for differences in ligand immobilization level using IRAS. The normalized analyte response with randomly oriented ligand was 2.5 times higher than that with ligand immobilized by CAP, probably due to molecular crowding effects on the surface and the fact that His-IgGFc is bivalent for protein A. This is a reminder that many other factors than orientation alone may play a decisive role in analyte binding on biosensor surfaces.

  • 4.
    Ericsson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Bui, Lan
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Site-Specific and Covalent Attachment of His-Tagged Proteins by Chelation Assisted Photoimmobilization: A Strategy for Microarraying of Protein Ligands2013In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, no 37, p. 11687-11694Article in journal (Refereed)
    Abstract [en]

    A novel strategy for site-specific and covalent attachment of proteins has been developed, intended for robust and controllable immobilization of histidine (His)-tagged ligands in protein microarrays. The method is termed chelation assisted photoimmobilization (CAP) and was demonstrated using human IgG-Fc modified with C-terminal hexahistidines (His-IgGFc) as the ligand and protein A as the analyte. Alkanethiols terminated with either nitrilotriacetic acid (NTA), benzophenone (BP); or oligo(ethylene glycol) were synthesized and mixed self-assembled monolayers (SAMs) were prepared on gold and thoroughly characterized by infrared reflection absorption spectroscopy (IRAS), ellipsometry, and contact angle goniometry. In the process of CAP, NTA chelates Ni2+ and the complex coordinates the His-tagged ligand in an oriented assembly. The ligand is then photoimmobilized via BP, which forms covalent bonds upon UV light activation. In the development of affinity biosensors and protein microarrays, site-specific attachment of ligands in a fashion where analyte binding sites are available is often preferred to random coupling. Analyte binding performance of ligands immobilized either by CAP or by standard amine coupling was characterized by surface plasmon resonance in combination with IRAS. The relative analyte response with randomly coupled ligand was 2.5 times higher than when site-specific attachment was used. This is a reminder that also when immobilizing ligands via residues far from the binding site, there are many other factors influencing availability and activity. Still, CAP provides a valuable expansion of protein immobilization techniques since it offers attractive microarraying possibilities amenable to applications within proteomics.

  • 5.
    Ericsson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Weissenrieder, Anna
    St Paul, USA.
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Glycerol monooleate-blood interactions2009In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 68, no 1, p. 20-26Article in journal (Refereed)
    Abstract [en]

    In the present study the initial blood compatibility of glycerol monooleate (GMO)-coated surfaces was evaluated after deposition to surfaces and in bulk. The model surface was silica onto which multiple layers of fibrinogen or human serum albumin (HSA) was immobilized. The protein-coated surfaces were subsequently dip-coated in GMO in ethanol and used for blood plasma and whole blood experiments. The characterization methods included null ellipsometry, scanning electron microscopy, imaging of coagulation, hemolysis test and whole blood coagulation time by free oscillation rheometry.

    The results showed a GMO film thickness of approximately 350 angstrom (similar to 4 mu g/cm(2)) upon dip-coating in ethanolic solution. A major part of the deposited layer detached in aqueous solutions, especially during shear conditions. The coagulation time on GMO was significantly prolonged compared to that on HSA coated silica. Whole blood tests showed that GMO is a very weak hemolytic agent. Deposited GMO detached easily from surfaces upon rinsing or shearing, although a stable layer with undefined phase structure and a thickness of 50-70 angstrom remained on HSA and fibrinogen precoated surfaces. This indicates that GMO has stronger adhesive forces to its substrate compared to the cohesive forces acting within the bulk GMO. The ability of GMO to detach from itself and tentatively form micelles or lipid bilayers when subjected to flowing blood may be of use in extravascular applications. It is concluded that GMO results in weak blood activation, and the material may in spite of this be suitable in selected biomaterial applications, especially as a biosealant and in colloidal dispersions.

  • 6.
    Ericsson, Emma M
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Bui, Lan
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Controlled orientation and covalent attachment of proteins on biosensor surfaces by Chelation Assisted Photoimmobilization2013Conference paper (Other academic)
    Abstract [en]

    In the context of surface chemistry for affinity biosensor chips, it is widely accepted that uniform orientation of the immobilized recognition element (ligand) is preferred over random orientation. However, this assumption has often been based on studies where differences in ligand immobilization level have not been taken into account. In this contribution, we present a novel two-step method for homogenous orientation and covalent attachment of proteins to sensing surfaces, called Chelation Assisted Photoimmobilization (CAP). Careful quantification of the effect of ligand orientation on analyte responses was performed by comparing this strategy to immobilization by conventional amine coupling.

     In CAP, the chelation agent is nitrilotriacetic acid (NTA) which chelates Ni2+. A His-tagged ligand forms an oriented assembly when binding Ni2+-NTA and is then covalently bound to the surface via photolabile benzophenone (BP), which attacks C-H bonds upon UV light activation. We relied on a surface chemistry based on self-assembled monolayers (SAMs) of oligo(ethylene glycol) (OEG)-containing alkanethiolates on gold. Alkanethiols terminated with either NTA, BP or OEG were synthesized and mixed SAMs were characterized by infrared reflection absorption spectroscopy (IRAS), ellipsometry and contact angle goniometry. IRAS was also used to quantify ligand immobilization levels obtained either by CAP or by amine coupling via the carboxyl groups of an NTA-presenting surface. The model ligand was human IgG-Fc modified with a C-terminal 6xHis-tag and the analyte was Protein A. The ligand-analyte interaction was quantified by a surface plasmon resonance biosensor.

     Analyte responses were normalized with respect to the ligand amounts obtained by the two immobilization strategies. Interestingly, the normalized analyte response with randomly oriented ligand was >2 times higher than that with ligand immobilized by CAP. This shows that oriented ligand immobilization is not necessarily a means of increasing the sensitivity of a biosensor. Factors that may influence performance include the valency of the ligand and constraints related to the surface chemistry used for orientation.

  • 7.
    Linderbäck, Paula
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Ericsson, Emma
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Alendronate release and binding at CaP interfaces2007In: ScanBalt Biomaterials Days,2007, 2007Conference paper (Other academic)
  • 8.
    Peng, Xinsheng
    et al.
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    Jeng, Jian
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    Ericsson, Emma
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    Ichinose, Izumi
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    General method for ultrathin free-standing films of nanofibrous composite materials2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 27, p. 8625-8633Article in journal (Refereed)
    Abstract [en]

    A simple and general method for the preparation of ultrathin, large-area, free-standing films of nanofibrous composite materials was developed. First, positively charged cadmium hydroxide nanostrands of 1.9 nm in diameter and micrometers in length were prepared by mixing dilute aqueous solutions of cadmium chloride and aminoethanol. Negatively charged dye molecules, proteins, nanoparticles, and water-soluble fullerene or carbon nanotubes were mixed with the nanostrands to give a well-dispersed solution of the corresponding nanofibrous composites. After filtration of the dispersions with a polycarbonate membrane filter, uniform films with a thickness of a few tens to hundreds of nanometers and a diameter of a few centimeters were obtained. The films were readily peeled off from the membrane filter by immersion in ethanol. The resultant free-standing films could be further transferred to other substrates, such as quartz plate, gold electrode, and porous alumina membrane, and were characterized by scanning and transmission electron microscopies. We provide herein various nanofibrous free-standing films with optical, biological, metallic, and magnetic properties.

  • 9.
    Rakickas, Tomas
    et al.
    Centre for Physics Science and Technology, Vilnius.
    Ericsson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Ruzele, Zivile
    Centre for Physics Science and Technology, Vilnius.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Valiokas, Ramunas
    Centre for Physics Science and Technology, Vilnius.
    Functional Hydrogel Density Patterns Fabricated by Dip-Pen Nanolithography and Photografting2011In: SMALL, ISSN 1613-6810, Vol. 7, no 15, p. 2153-2157Article in journal (Refereed)
    Abstract [en]

    n/a

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