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Larsson (Kaiser), Andréas
Publications (10 of 10) Show all publications
Ekblad, T., Faxälv, L., Andersson, O., Wallmark, N., Larsson (Kaiser), A., Lindahl, T. L. & Liedberg, B. (2010). Patterned Hydrogels for Controlled Platelet Adhesion from Whole Blood and Plasma. Advanced Functional Materials, 20(15), 2396-2403
Open this publication in new window or tab >>Patterned Hydrogels for Controlled Platelet Adhesion from Whole Blood and Plasma
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2010 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 20, no 15, p. 2396-2403Article in journal (Refereed) Published
Abstract [en]

This work describes the preparation and properties of hydrogel surface chemistries enabling controlled and well-defined cell adhesion. The hydrogels may be prepared directly on plastic substrates, such as polystyrene slides or dishes, using a quick and experimentally simple photopolymerization process, compatible with photolithographic and microfluidic patterning methods. The intended application for these materials is as substrates for diagnostic cell adhesion assays, particularly for the analysis of human platelet function. The adsorption of fibrinogen and other platelet promoting molecules is shown to be completely inhibited by the hydrogel, provided that the film thickness is sufficient (>5 nm). This allows the hydrogel to be used as a matrix for presenting selected bioactive ligands without risking interference from nonspecifically adsorbed platelet adhesion factors, even in undiluted whole blood and blood plasma. This concept is demonstrated by preparing patterns of proteins on hydrogel surfaces, resulting in highly controlled platelet adhesion. Further insights into the protein immobilization and platelet adhesion processes are provided by studies using imaging surface plasmon resonance. The hydrogel surfaces used in this work appear to provide an ideal platform for cell adhesion studies of platelets, and potentially also for other cell types.

Place, publisher, year, edition, pages
John Wiley & Sons, 2010
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-54301 (URN)10.1002/adfm.201000083 (DOI)000281058900003 ()
Available from: 2010-03-08 Created: 2010-03-08 Last updated: 2017-12-12
Andersson, O., Larsson (Kaiser), A., Ekblad, T. & Liedberg, B. (2009). Gradient Hydrogel Matrix for Microarray and Biosensor Applications: An Imaging SPR Study. Biomacromolecules, 10(1), 142-148
Open this publication in new window or tab >>Gradient Hydrogel Matrix for Microarray and Biosensor Applications: An Imaging SPR Study
2009 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 1, p. 142-148Article in journal (Refereed) Published
Abstract [en]

A biosensor matrix based on UV-initiated graft copolymerized poly(ethylene glycol) methacrylate and 2-hydroxyethyl methacrylate has been studied using imaging surface plasmon resonance (iSPR). By using a photo mask and a programmable shutter to vary the exposure time laterally, a gradient of matrix spots with physical thicknesses ranging from a few to tens of nanometers was generated. To maximize the dynamic range, imaging SPR was employed in wavelength interrogation mode. By finding the minimum in the reflectance spectra from each pixel of an image, SPR wavelength maps were constructed. The shift in SPR wavelength upon biospecific interaction was then measured both as a function of matrix thickness and composition. The performance of the matrix was evaluated in terms of immobilization of human serum albumin, biomolecular interaction with its antibody, and nonspecific binding of human fibrinogen. In addition, a low molecular weight interaction pair based on a synthetic polypeptide and calmodulin was also studied to explore the size selectivity of the hydrogel matrix. Our results show that the gradient matrix exhibits excellent properties for quick evaluation and screening of optimal hydrogel performance. The mixed hydrogel matrices display very low levels of nonspecific binding. It is also evident that the low molecular weight calmodulin is capable of freely diffusing and interacting throughout the entire hydrogel matrix, whereas the much larger albumin and its corresponding antibody, in particular, are partly/completely hindered from penetrating the interior of the matrix. This size-selectivity is attributed to a significant UV-initiated cross-linking or branching of the matrix during fabrication and/or protein mediated multipoint attachment during immobilization.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-16523 (URN)10.1021/bm801029b (DOI)
Available from: 2009-01-30 Created: 2009-01-30 Last updated: 2017-12-14
Andersson, O., Larsson (Kaiser), A., Ekblad, T. & Liedberg, B. (2008). Imaging surface plasmon resonance studies of hydrogel and gradient surfaces for biosensor and array applications. In: Europtrode IX,2008: . Paper presented at Europtrode IX - Dublin, March 30th – April 2nd, 2008.
Open this publication in new window or tab >>Imaging surface plasmon resonance studies of hydrogel and gradient surfaces for biosensor and array applications
2008 (English)In: Europtrode IX,2008, 2008Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-43327 (URN)73524 (Local ID)73524 (Archive number)73524 (OAI)
Conference
Europtrode IX - Dublin, March 30th – April 2nd, 2008
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-10-13
Viljanen, J., Larsson, J., Larsson (Kaiser), A. & Broo, K. S. (2007). A Multipurpose Receptor Composed of Promiscuous Proteins. Analyte Detection through Pattern Recognition. Bioconjugate Chemistry, 18(6), 1935-1945
Open this publication in new window or tab >>A Multipurpose Receptor Composed of Promiscuous Proteins. Analyte Detection through Pattern Recognition
2007 (English)In: Bioconjugate Chemistry, ISSN 1043-1802, Vol. 18, no 6, p. 1935-1945Article in journal (Refereed) Published
Abstract [en]

A multipurpose receptor akin to the “electronic nose” was composed of coumarin-labeled mutants of human glutathione transferase A1. We have previously constructed a kit for site-specific modification of a lysine residue (A216K) using a thiol ester of glutathione (GSC-Coubio) as a modifying reagent. In the present investigation, we scrambled the hydrophobic binding site (H-site) of the protein scaffold through mutations at position M208 via random mutagenesis and isolated a representative library of 11 A216K/M208X mutants. All of the double mutants could be site-specifically labeled to form the K216Cou conjugates. The labeled proteins responded to the addition of different analytes with signature changes in their fluorescence spectra resulting in a matrix of 96 data points per analyte. Ligands as diverse as n-valeric acid, fumaric acid monoethyl ester, lithocholic acid, 1-chloro-2,4-dinitrobenzene (CDNB), glutathione (GSH), S-methyl-GSH, S-hexyl-GSH, and GS-DNB all gave rise to signals that potentially can be interpreted through pattern recognition. The measured Kd values range from low micromolar to low millimolar. The cysteine residue C112 was used to anchor the coumarin-labeled protein to a PEG-based hydrogel chip in order to develop surface-based biosensing systems. We have thus initiated the development of a multipurpose, artificial receptor composed of an array of promiscuous proteins where detection of the analyte occurs through pattern recognition of fluorescence signals. In this system, many relatively poor binders each contribute to detailed readout in a truly egalitarian fashion.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-13198 (URN)10.1021/bc700247x (DOI)
Available from: 2008-04-28 Created: 2008-04-28 Last updated: 2015-10-13
Larsson (Kaiser), A. (2007). Biochip design based on tailored ethylene glycols. (Doctoral dissertation). Institutionen för fysik, kemi och biologi
Open this publication in new window or tab >>Biochip design based on tailored ethylene glycols
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Studies of biomolecular interactions are of interest for several reasons. Beside basic research, the knowledge gained from such studies is also very valuable in for example drug target identification. Medical care is another area where biomolecules may be used as biomarkers to aid physicians in making correct diagnosis. In addition, the highly specific interactions between antibodies and almost any substance opens up the possibilities to design systems for detection of trace amounts of both biological and non-biological substances within environmental restoration, law enforcement, correctional care, customs service and national security. A biochip, which contains a biologically active material, offers a means of monitoring the molecular interactions in the above applications in a sensitive and specific manner. The biochip is a key component of a biosensor, which also includes components for transforming the interaction events into a human-readable signal.

This thesis describes the use of poly(ethylene glycol) (PEG) in biochip design. Two different approaches are presented, the first based on ethylene glycol (EG)-containing alkyl thiol self-assembled monolayers (SAMs) on flat gold and the second on photo-induced graft copolymerisation of PEG-containing methacrylate monomers onto various substrates. The former is a two dimensional system where EG-terminated thiols are mixed with similar thiols presenting tail groups that mimic the explosive substance 2,4,6-trinitrotoluene (TNT). In an immunoassay, the detection limit for TNT was determined to fall in the range 1-10 µg/L. In the second approach, a branched three dimensional biosensor matrix (hydrogel) is proposed. The carboxymethylated (CM) dextran matrix, which is commonly used within the biosensing community, is not always ideal for studies of biointeractions, due to the non-specific binding frequently encountered in work with complex biological solutions and various proteins. To employ PEG, which displays a low non-specific binding of such species, is therefore an interesting option worth investigating. The use of a branched graft polymerised PEG matrix in biosensor applications is novel as compared to previous reports which have focused on linear PEG chains. The latter approach provides, at maximum, one functional group, per surface anchoring point, for immobilisation of sensor elements. Thus, it has the inherited disadvantage that it limits the number of available immobilisation sites. The present PEG matrix contains a large number of functional groups, for immobilisation of sensor elements, per grafting site and offers the potential of improved response upon binding to the analyte as demonstrated in a series of successful sensor experiments.

Furthermore, the nature of the process enables easy preparation of matrix patterns and gradients. In a PEG matrix gradient, protein permeability is studied and the capabilities of immobilising proteins are demonstrated. By combining the patterning technique with different monomers in a two-step process, an inert platform, lacking chemical attachment sites, is provided with arrays of spots (with immobilisation capabilities), which are conveniently addressed via microdispensing and used for biosensor purposes. The EG-terminated thiols present another means of generating such inert platforms, a route which is also investigated. To further explore the sensor quality of these spots, the concepts of patterning and gradient formation are combined and studied.

Abstract [sv]

Det är intressant att studera biomolekylära interaktioner av många anledningar. För att kunna bedriva framgångsrik läkemedelsutveckling är det oerhört viktigt att känna till hur olika molekyler samverkar i människokroppen. Inom sjukvården kan biomolekyler användas som biomarkörer, då närvaro av dem eller förändringar av deras koncentrationer är kopplade till sjukdomstillstånd, och därmed hjälper läkaren att ställa rätt diagnos. Dessutom kan de mycket specifika interaktionerna mellan antikroppar och (i princip) valfri substans användas för detektion av spårämnen vid miljösaneringsarbete, gränskontroller, polisarbete, fängelser och arbete med nationell säkerhet.

Den här avhandlingen beskriver hur polymeren polyetylenglykol (PEG) kan användas vid design av biochip. Ett biochip är en liten anordning, som kan användas för att detektera specifika molekyler med hjälp av en biologisk interaktion. Traditionellt har PEG använts inom biomaterialsektorn, men återfinns även i hygienartiklar som tvål och tandkräm. Ett annat användningsområde är konservering av bärgade träskepp och i en del litiumjonbatterier ingår PEG som en komponent. Dessutom pågår utveckling av PEG-innehållande skyddsvästar. I det här arbetet används PEG framför allt på grund av sin förmåga att minimera ospecifik inbindning av proteiner, som utgör en stor del av gruppen biomolekyler, till ytor på biochip. Två olika typer av ytbeläggningar, som innehåller den här polymeren, har använts. Den första typen ger mycket tunna (~0.000003 mm), tvådimensionella filmer medan den andra ger en något tjockare (~0.00005 mm), tredimensionell struktur (matris). De tvådimensionella filmerna har använts för att utveckla en sprängämnesdetektor med mycket hög känslighet (detektionsgräns mellan 1-10 ppb). En viktig beståndsdel i detta system är antikroppar riktade mot sprängämnet trinitrotoluen (TNT). Den tredimensionella matrisen är mer generell och kan användas för att studera många olika molekylära interaktioner. Tillverkningsmetoden av matrisen är baserad på belysning med ultraviolett ljus och är därmed lämpad för att skapa mönstrade ytor. Genom att blockera delar av ljusflödet begränsas tillväxten av matrisen till de belysta delarna. På så sätt har bland annat så kallade mikro-arrayer, bestående av mikrometerstora (tusendels millimeter) strukturer i ett regelbundet mönster, tillverkats. Tekniken tillåter även tillverkning av gradienter, där matrisens tjocklek varierar längs med provet, genom att belysa olika delar av provytan olika länge. Genom att undersöka dessa gradienter har information om matrisens genomsläpplighet för proteiner kunnat extraheras. Gradientkonceptet har även kombinerats med mikro-arraytillverkningen och gett möjlighet att studera interaktioner mellan flera olika modellproteiner och deras motsvarande antikroppar i olika tjocka matriser på en och samma yta.

Det finns ett stort antal sätt att utnyttja interaktionerna mellan olika molekyler på ett biochip. Ett tilltalande tillvägagångssätt är exempelvis att i en mikro-array binda in olika molekyler som kan fånga kliniskt intressanta biomolekyler, i syfte att skapa en hälsoprofil. Ett sådant biochip skulle ge möjlighet att parallellt detektera eller bestämma koncentrationen av ett stort antal biomolekyler i till exempel en droppe blod. På så sätt kan en diagnos snabbt ställas, kanske till och med utan att patienten behöver uppsöka sjukvården. Den utvecklade PEG-matrisen har god potential att fungera i en sådan applikation.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi, 2007
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1111
Keywords
Biosensor, biochip, poly(ethylene glycol), self-assembled monolayer, photopolymerisation, microarray, biomolecular interaction, explosives detection
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-9578 (URN)978-91-85831-54-8 (ISBN)
Public defence
2007-09-13, Planck, Fysikhuset, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2007-10-12 Created: 2007-10-12 Last updated: 2015-10-13
Larsson (Kaiser), A., Ekblad, T., Andersson, O. & Liedberg, B. (2007). Photografted poly(ethylene glycol) matrix for affinity interaction studies. Biomacromolecules, 8(1), 287-295
Open this publication in new window or tab >>Photografted poly(ethylene glycol) matrix for affinity interaction studies
2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 1, p. 287-295Article in journal (Refereed) Published
Abstract [en]

A poly(ethylene glycol) (PEG)-based matrix for studies of affinity interactions is developed and demonstrated. The PEG matrix, less than 0.1 μm thick, is graft copolymerized onto a cycloolefin polymer from a mixture of PEG methacrylates using a free radical reaction initiated by UV light at 254 nm. The grafting process is monitored in real time, and characteristics such as thickness, homogeneity, relative composition, photostability, and performance in terms of protein resistance in complex biofluids and sensor qualities are investigated with null ellipsometry, infrared spectroscopy, and surface plasmon resonance. The matrix is subsequently modified to contain carboxyl groups, thereby making it possible to immobilize ligands in a controlled and functional manner. Human serum albumin and fibrinogen are immobilized and successfully detected by antibody recognition using surface plasmon resonance. The results are encouraging and suggest that the PEG matrix is suitable for biochip and biosensor applications in demanding biofluids.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-14606 (URN)10.1021/bm060685g (DOI)
Available from: 2007-10-12 Created: 2007-10-12 Last updated: 2017-12-13
Larsson (Kaiser), A. & Liedberg, B. (2007). Poly(ethylene glycol) gradient for biochip development. Langmuir, 23(22), 11319-11325
Open this publication in new window or tab >>Poly(ethylene glycol) gradient for biochip development
2007 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 22, p. 11319-11325Article in journal (Refereed) Published
Abstract [en]

A novel method of producing a poly(ethylene glycol) (PEG)-based gradient matrix that varies gradually in thickness from 0 to 500 Å over a distance of 5−20 mm is presented. The gradient matrix is graft copolymerized from a mixture of PEG methacrylates onto organic thin films providing free radical polymerization sites initiated by UV irradiation at 254 nm. The films used as grafting platforms consist of either a spin-coated cycloolefin polymer or a self-assembled monolayer on planar gold. The thickness/irradiation gradient is realized by means of a moving shutter that slowly uncovers the modified gold substrate. The structural and functional characteristics of the gradient matrix are investigated with respect to thickness profile, degree of carboxylation, and subsequent immobilization of two model proteins of different sizes and shapes. These characteristics are studied with ellipsometry and infrared reflection−absorption microscopy using a grazing angle objective. It is revealed that the relatively small carboxylation agent used offers homogeneous activation throughout the gradient, even in the thick areas, whereas the diffusion/interpenetration and subsequent immobilization of large proteins is partially hindered. This is crucial information in biosensor design that can be easily obtained from a gradient experiment on a single sample. Moreover, the partially hindered protein interpenetration, the marginal swelling upon hydration, and the unspecific nature of the graft polymerization suggest a matrix growth mechanism that favors the formation of a bushlike polymer structure with a certain degree of cross linking.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-14607 (URN)10.1021/la700729q (DOI)
Available from: 2007-10-12 Created: 2007-10-12 Last updated: 2017-12-13
Larsson (Kaiser), A., Du, C.-X. & Liedberg, B. (2007). UV-patterned poly(ethylene glycol) matrix for microarray applications. Biomacromolecules, 8(11), 3511-3518
Open this publication in new window or tab >>UV-patterned poly(ethylene glycol) matrix for microarray applications
2007 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 11, p. 3511-3518Article in journal (Refereed) Published
Abstract [en]

A versatile method to fabricate polymeric matrixes for microarray applications is demonstrated. Several different design strategies are presented where a variety of organic films, such as plastic polymers and self-assembled monolayers (SAMs) on planar silica and gold substrates, act as supports for the graft polymerization procedure. An ensemble of poly(ethylene glycol) methacrylate monomers are combined to obtain a matrix with desired properties:  low nonspecific binding and easily accessible groups for postimmobilization of ligands. The free radical graft polymerization process occurs under irradiation with UV light in the 254−266 nm range, which offers the possibility to introduce patterns by means of a photomask. The arrays are created on inert and homogeneous coatings prepared either by graft polymerization of a methoxy-terminated PEG−methacrylate or self-assembly of a methoxy-terminated oligo(ethylene glycol) thiol. Carboxylic acid groups, introduced in the array spots either during graft polymerization or upon wet chemical conversion of hydroxyls, grant the capability to immobilize proteins and other molecules via free amine groups. Immobilization of fluorescent species as well as biotin followed by exposure to a fluorescently labeled antibody directed toward biotin display both excellent integrity of the spots and low nonspecific binding to the surrounding framework. Beside patterns of uniform height and size, an array of spots with varying thickness (a sort of gradient) is demonstrated. Such gradient samples enable us to address critical issues regarding the mechanism(s) behind spatially resolved free radical polymerization of methacrylates. It also offers a convenient route to optimize the matrix properties with respect to thickness, loading capacity, protein diffusion/penetration, and nonspecific binding.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-14608 (URN)10.1021/bm700707s (DOI)
Available from: 2007-10-12 Created: 2007-10-12 Last updated: 2017-12-13
Larsson (Kaiser), A., Angbrant, J., Ekeroth, J., Månsson, P. & Liedberg, B. (2006). A novel biochip technology for detection of explosives - TNT: Synthesis, characterisation and application. Sensors and Actuators B: Chemical, 113(2), 730-748
Open this publication in new window or tab >>A novel biochip technology for detection of explosives - TNT: Synthesis, characterisation and application
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2006 (English)In: Sensors and Actuators B: Chemical, ISSN 0925-4005, Vol. 113, no 2, p. 730-748Article in journal (Refereed) Published
Abstract [en]

This contribution describes the synthesis, characterisation and evaluation of a novel biochip technology for the detection of the explosive substance 2,4,6-trinitrotoluene (TNT). Two types of thiols are self-assembled to produce the biochip on gold, namely oligo(ethylene glycol) (OEG)-alkyl thiols terminated with a hydroxyl group and a TNT-analogue (2,4-dinitrobenzene), respectively. Three different TNT-analogues are mixed in various proportions with hydroxyl-terminated OEG-thiols to obtain highly selective and sensitive biochips with a low non-specific binding. The produced self-assembled monolayers (SAMs) are thoroughly characterised with null ellipsometry, contact angle goniometry, infrared reflection absorption spectroscopy (IRAS) and X-ray photoelectron spectroscopy (XPS) and they all meet high standards in terms of molecular conformation, packing and orientation. The biochip is designed to function as a platform for a competitive label-free immunoassay and two real-time transducers – surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) – are used to monitor the dissociation of on-line immobilised monoclonal antibodies produced against TNT. The three TNT-analogues are all potential candidates for the development of a functional biochip, though one of them displayed superior properties in terms of shorter recovery/stabilisation time after antibody immobilisation and a better response/loading capacity ratio. This is particularly evident when using low antigen (TNT-analogue) content in the mixed SAM.

Keywords
Explosives; Competitive immunoassay; Self-assembled monolayers; Quartz crystal microbalance; Surface plasmon resonance
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-14605 (URN)10.1016/j.snb.2005.07.025 (DOI)
Available from: 2007-10-12 Created: 2007-10-12 Last updated: 2015-10-13
Liedberg, B., Larsson (Kaiser), A., Ekblad, T. & Andersson, O. (2006). Photografted PEG matrix for biosensor applications. In: Proceedings of the 9th Biosensors Congress,2006: . Paper presented at 9th World Congress on Biosensors, 2006-05-10 - 2006-05-12, Toronto, Canada. Columbus: American Chemical Society
Open this publication in new window or tab >>Photografted PEG matrix for biosensor applications
2006 (English)In: Proceedings of the 9th Biosensors Congress,2006, Columbus: American Chemical Society , 2006Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Columbus: American Chemical Society, 2006
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-35752 (URN)28429 (Local ID)28429 (Archive number)28429 (OAI)
Conference
9th World Congress on Biosensors, 2006-05-10 - 2006-05-12, Toronto, Canada
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-10-13Bibliographically approved
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