| 1. |
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| 2. |
- Fromell, Karin, et al.
(author)
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A particulate platform for bioluminescent immunosensing
- 2007
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 79:22, s. 8601-8607
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Journal article (peer-reviewed)abstract
- The present study examines pyruvate kinase-conjugated antibodies for potential use in EUSA applications. The conjugates had an acceptable stability, and the coupling inflicted only minor impairment on the kinase activity. To mimic the setup of an immunoassay under development, a test antigen (BSA) was attached to polystyrene nanoparticles. This arrangement was found to be suitable as solid support for presentation of antigens in sensitive bioluminescence assays. The nanoparticles were well characterized in terms of protein surface load and were used to establish the number of conjugate complexes needed to generate a detectable signal. Under the biochemical conditions employed here, the detection limit of the pyruvate kinase conjugate lies in the femtomole range.
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| 3. |
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| 4. |
- Gullberg, Elisabet, et al.
(author)
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Identification of Cell Adhesion Molecules in the Human Follicle-Associated Epithelium That Improve Nanoparticle Uptake into the Peyer's Patches
- 2006
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In: Journal of Pharmacology and Experimental Therapeutics. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0022-3565 .- 1521-0103. ; 319:2, s. 632-639
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Journal article (peer-reviewed)abstract
- The aim of this study was to identify cell adhesion molecules that could serve as targets of the human follicle-associated epithelium (FAE) overlying Peyer's patches and to assess nanoparticle uptake levels across this epithelium. We first studied the expression of the mouse M-cell marker beta(1)-integrin and used a model of human FAE derived from intestinal epithelial Caco-2 cells and Raji B-cells to identify additional potential targets by cDNA array. The protein expression of potential targets in the model FAE and in human ileal FAE tissues was quantified by immunofluorescence. Integrin targeting was studied by investigating the transport of Arg-Gly-Asp (RGD)-coated (integrin- binding), Arg-Gly-Glu (RGE)-coated (nonintegrin-binding), and uncoated nanoparticles across ileal specimens mounted in Ussing chambers. Both beta(1)-integrin and the cell adhesion molecule CD9 were more abundantly expressed in the model and human FAE compared with the Caco-2 control cells or villus epithelium (VE). Uncoated nanoparticles were not taken up across either FAE or VE. General integrin targeting with RGD improved the nanoparticle transport dramatically across the FAE and to a lower extent across the VE. Compared with RGE, RGD improved transport 4-fold across the FAE. There was no difference in the transport of RGD- and RGE-coated nanoparticles across the VE. In conclusion, beta(1)-integrin and CD9 were identified as targets in human FAE. The difference in RGD- and RGE-mediated transport across the FAE, but not the VE, suggests that a specific integrin interaction was the dominating mechanism for improved nanoparticle uptake across the FAE., whereas charge interaction contributed substantially to the improved VE uptake.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Caldwell, Karin D., et al.
(author)
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The Origin of Sepahdex
- 2006
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In: GIT Laboratory Journal: Europe. ; 10:5, s. 18-20
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Journal article (other academic/artistic)
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| 10. |
- Dahlin, Andreas P., et al.
(author)
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Methodological aspects on microdialysis protein sampling and quantification in biological fluids : an in vitro study on human ventricular CSF.
- 2010
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 82:11, s. 4376-4385
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Journal article (peer-reviewed)abstract
- There is growing interest in sampling of protein biomarkers from the interstitial compartment of the brain and other organs using high molecular cutoff membrane microdialysis (MD) catheters. However, recent data suggest that protein sampling across such MD membranes is a highly complex process that needs to be further studied. Here, we report three major improvements for microdialysis sampling of proteins in complex biological matrixes. The improvements in this in vitro study using human ventricular cerebrospinal fluid as the sample matrix include increased fluid recovery control, decreased protein adsorption on the microdialysis membrane and materials, and novel quantitative mass spectrometry analysis. Dextrans in different concentrations and sizes were added to the perfusion fluid. It was found that dextrans with molecular mass 250 and 500 kDa provided a fluid recovery close to 100%. An improved fluid recovery precision could be obtained by self-assembly triblock polymer surface modification of the MD catheters. The modified catheters also delivered a significantly increased extraction efficiency for some of the investigated proteins. The final improvement was to analyze the dialysates with isobaric tagged (iTRAQ) proteomics, followed by tandem mass spectrometric analysis. By using this technique, 48 proteins could be quantified and analyzed with respect to their extraction efficiencies. The novel aspects of microdialysis protein sampling, detection, and quantification in biological fluids presented in this study should be considered as a first step toward better understanding and handling of the challenges associated with microdialysis sampling of proteins. The next step is to optimize the developed methodology in vivo.
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| 11. |
- Feiler, Adam A., et al.
(author)
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Adsorption and viscoelastic properties of fractionated mucin (BSM) and bovine serum albumin (BSA) studied with quartz crystal microbalance (QCM-D)
- 2007
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In: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 315:2, s. 475-481
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Journal article (peer-reviewed)abstract
- The adsorption profile and viscoelastic properties of bovine submaxillary gland mucin (BSM) and bovine serum albumin (BSA), extracted from a commercial mucin preparation, adsorbing to polystyrene surfaces has been studied using quartz crystal microbalance with dissipation monitoring (QCM-D). A significant difference in the adsorption properties of the different proteins was detected; with the BSA adsorbing in a flat rigid layer whilst the mucin adsorbed in a diffuse, highly viscoelastic layer. Subsequent addition of BSA to the preadsorbed mucin layer resulted in stiffening of the protein layer which was attributed to complexation of the mucin by BSA. In contrast, a preadsorbed layer of BSA prevented mucin adsorption altogether. Combined mixtures of mucin and BSA in well defined ratios revealed intermediate properties between the two separate protein species which varied systematically with the protein ratios. The results shed light on the synergistic effects of complexation of lower molecular weight biomolecular species with mucin. The possibility to selectively control protein uptake and tailor the physical properties of the adsorbed layer makes mucin an attractive option for application in biomaterial coatings.
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| 12. |
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| 13. |
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| 14. |
- Huang, Shao-Chie, et al.
(author)
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Structural integrity in protein immobilization.
- 1997
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In: Polymer Preprints. - : The Division of PolymerChemistry, Inc.; American Chemical Society. ; , s. 561-562
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Conference paper (other academic/artistic)
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| 15. |
- Lundin, Maria, et al.
(author)
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Comparison of the adsorption kinetics and surface arrangement of "as received" and purified bovine submaxillary gland mucin (BSM) on hydrophilic surfaces
- 2009
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In: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 336:1, s. 30-39
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Journal article (peer-reviewed)abstract
- The effect of bovine serum albumin (BSA) as impurity in a commercial bovine submaxillary gland mucin preparation (BSM; Sigma M3895) on the adsorption of BSM to hydrophilic surfaces (mica and silica) has been Studied in terms of adsorption kinetics, amount and structure of the formed adlayer. The Surface Force Apparatus (SFA) was used to gain information about the extended and compressed structure of adsorbed "as received" BSM, purified BSM, BSA extracted from the "as received" BSM and mixtures of the latter Purified proteins. The adsorbed amount was estimated using a combination of X-ray Photoelectron Spectroscopy (XPS), Enzyme-Linked Immuno Sorbent Assay (ELISA), Enzyme-Linked Lectin Assay (ELLA), Dual Polarization Interferometry (DPI) and Quartz Crystal Microbalance (QCM-D) measurements. Under the used conditions, purified BSM showed very low affinity for silica and only small amounts were found to adsorb on mica. Initially, the BSM molecules adopted an extended conformation on the mica surface with tails extending into the bulk phase. These tails were irreversibly compressed into a very thin (10 A) layer upon applying a high load. "As received" BSM formed considerably thicker Compressed layers (35 A); however, the extended layer structure was qualitatively the same. When Mixtures of purified BSM and BSA were coadsorbed on mica, a 9 wt-% albumin content gave a comparable layer thickness as the "as received" BSM and from XPS data we draw the conclusion that the albumin content in the layer adsorbed from "as received" BSM was approximately 5 wt-%. Adsorption from an equal amount of BSM and BSA revealed that even though the amount of BSM is scarce in the mixed layer, the few BSM molecules have a drastic effect on the adsorbed thickness and Structure. Clearly, this study shows the importance of characterizing the mucin used since differences in purity give rise to different adsorption behaviours in terms of both adsorbed amount and layer Structure. (C) 2009 Elsevier Inc. All rights reserved.
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| 16. |
- Margreiter, Gerd, et al.
(author)
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Size characterization of inclusion bodies by sedimentation field-flow fractionation
- 2008
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In: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 138:3-4, s. 67-73
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Journal article (peer-reviewed)abstract
- Sedimentation field-flow fractionation (sedFFF) was evaluated to characterize the size of Delta(4-23)TEM-beta-lactamase inclusion bodies (IBs) overexpressed in fed-batch cultivations of Escherichia coli. Heterologous Delta(4-23)TEM-beta-lactamase protein formed different sizes of IBs, depending upon the induction conditions. In the early phases of recombinant protein expression, induced with low concentrations of IPTG (isopropyl-beta-d-thiogalactoside), IB masses were larger than expected and showed heterogeneous size distributions. During cultivation, IB sizes showed a Gaussian distribution and reached a broad range by the end of the fed-batch cultivations. The obtained result proved the aptitude of sedFFF to rapidly assess the size distribution of IBs in a culture.
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| 17. |
- Nilsson, Lars, et al.
(author)
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Starch and other polysaccharides
- 2012. - 1
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In: Field-flow fractionation in biopolymer analysis. - Vienna : Springer Vienna. - 9783709101537 - 9783709101544 ; , s. 165-185
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Book chapter (peer-reviewed)abstract
- Polysaccharides constitute one of the major groups of biological macromolecules and they include some of the most abundant macromolecules in nature. In this chapter instrumental considerations when analyzing polysaccharides with flow field-flow fractionation (flow FFF) are briefly discussed. Furthermore, an overview of characterized properties is given with special attention to multi angle light scattering. Included is an extensive review of literature on applications regarding flow FFF and polysaccharides.
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| 18. |
- Sandberg, Tomas, et al.
(author)
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Potential use of mucins as biomaterial coatings. I. Fractionation, characterization, and model adsorption of bovine, porcine, and human mucins
- 2009
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In: Journal of Biomedical Materials Research Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 91A:3, s. 762-772
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Journal article (peer-reviewed)abstract
- Previously, we presented evidence that mucins have potential as biomaterial coatings. Here, we reveal substantial batch-to-batch variations for a frequently used commercial bovine salivary mucin preparation (BSM) and stress the importance of standardizing mucins intended for comparative purposes. "Mild" fractionation strategies, aiming at preserving natural mucin functions, were used to prepare two more defined BSM fractions as well as three mucin fractions from porcine gastric (PGM) and human salivary (MG1) sources. While the BSM and PGM were highly purified and mainly adopted random coil conformations in solution, the MG1 contained mucin-bound components (1.6 wt% albumin) and appeared compact. Average molar masses and root-mean-square radii for the predominant BSM, PGM, and MG1 species spanned 0.8-4.2 MDa and 46-86 nm, respectively. An ellipsometric evaluation, using hydrophilic and hydrophobic silica, showed the mucin adsorption to be slow and related to mucin charge, size, conformation, and compositional complexity. The mass uptakes on hydrophobic silica averaged 2.6, 2.6, and 5.0 mg/m(2), for BSM, PGM, and MG1, respectively. Finally, we find that stable mucin coatings can be formed on polymers of different wettability. The reported mucin preparations serve as platforms for a series of studies on the biocompatibility of mucin coatings.
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| 19. |
- Sandberg, Tomas, et al.
(author)
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Potential use of mucins as biomaterial coatings. II. Mucin coatings affect the conformation and neutrophil-activating properties of adsorbed host proteins – Towards a mucosal mimic
- 2009
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In: Journal of Biomedical Materials Research: Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 91A:3, s. 773-785
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Journal article (peer-reviewed)abstract
- In continuation of our recent fractionation and characterization study on mucins of bovine salivary (BSM), porcine gastric (PGM), and human salivary (MG1) origin, this study evaluates the effect of mucin precoating on the conformation and neutrophil-activating properties of host proteins adsorbed to a polyethylene terephthalate-based model biomaterial. Microscopy combined with assays for the neutrophil releases of reactive oxygen species and human neutrophil lipocalin showed that mucin precoating greatly reduced the strong immune-response normally induced by adsorbed immunoglobulin G (IgG) and secretory immunoglobulin A (sIgA), respectively. A similar finding was made for the proinflammatory fibrinogen. Although the total uptakes of these proteins depended on the mucin surface concentration, a detailed composite analysis suggested the fraction Of surface-exposed protein to be a stronger determinant of coating performance. The unexpectedly low neutrophil activation showed by composites containing near-monolayer concentrations of exposed IgG and sIgA, respectively, suggested that these act synergistically with mucin on the surface. In support of this hypothesis, quartz crystal microbalance with dissipation monitoring measurements revealed that a preadsorbed BSM layer stabilizes IgG through complexation on a polymeric model surface. Our findings link well to the complex in vivo situation and suggest that functional mucosal mimics can be created in situ for improved biomaterials performance.
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| 20. |
- Sandberg, Tomas, et al.
(author)
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Surface analysis of pure and complex mucin coatings
- 2009
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In: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 333:1, s. 180-187
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Journal article (peer-reviewed)abstract
- In the past, we introduced the idea of using mucin coatings to improve biomaterials performance. Here, we evaluate non-radioactive methods for the analysis of pure and human host protein-containing (complex) mucin coatings on a real-type substrate (Thermanox). A common protein quantification assay (mBCA) was combined with mass-calibrated, enzyme-amplified assays based on lectin (ELLA) and antibody (ELISA) recognition, to determine the total and specific amounts of surface-associated proteins. Model studies showed the mBCA assay to be of limited use at low mass loads, and steric effects to influence the ELLA at high surface layer densities. Non-specific responses due to substrate interaction were low for the ELLA and ELISAs. Cross-reactions were observed during ELLA analysis of analytes sharing high degree of O-glycosylation. Combined mBCA-ELLA-ELISA analysis suggested that mucin desorption was low upon protein addition and that low concentrations of ELISA-determined Protein for the complex coatings Could be explained in terms of low accessibility of proteins to the bulk environment. Specifically, a methodology is presented for the determination of the fraction of surface-exposed, presumed bioactive proteins in a complex mucin coating. Finally, X-ray photoelectron spectroscopy and infrared reflectance spectroscopy combined with multivariate data analysis were proven useful in the evaluation of mucin-based coatings.
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| 21. |
- Wahlund, Karl-Gustav, et al.
(author)
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Flow FFF–basics and key applications
- 2012. - 1
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In: Field-flow fractionation in biopolymer analysis. - Vienna : Springer Vienna. - 9783709101537 - 9783709101544 ; , s. 1-21
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Book chapter (peer-reviewed)abstract
- The 1990s and 2000s have seen a rapidly growing use of flow field-flow fractionation (flow FFF, FlFFF). As of today hundreds of publications in many different application areas are presented each year in which flow FFF has been used or is referred to. In this chapter a brief historical overview of flow FFF is given. Channel designs and basic principles are discussed as well as approaches to development of rapid high resolution separations. Finally, an overview of key applications is included with pioneering and ground-breaking papers from literature.
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| 22. |
- Webb, Ken, et al.
(author)
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A novel surfactant-based immobilization method for varying substrate-bound fibronectin
- 2001
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In: JOURNAL OF BIOMEDICAL MATERIALS RESEARCH. - : JOHN WILEY & SONS INC. - 0021-9304. ; 54:4, s. 509-518
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Journal article (peer-reviewed)abstract
- Most biomaterials can be rendered adhesive for anchorage-dependent cells by adsorption of serum, isolated extracellular matrix proteins, or immobilization of peptide sequences. However, difficulties are frequently encountered in characterizing the adsorbe
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| 23. |
- Williams, S. Kim R., et al.
(author)
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Field-flow fractionation
- 2014
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In: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 406:6, s. 1577-1578
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Journal article (other academic/artistic)
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| 24. |
- Åsberg, Peter, 1973-
(author)
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Hydrogels of conjugated polyelectrolytes for biosensor and biochip applications
- 2005
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Doctoral thesis (other academic/artistic)abstract
- This thesis describes the use of conjugated polyelectrolytes (CPEs) in biosensor devices. The method is based on non-covalent assembly of the biomolecule of interest and the CPE functioning as the reporter, in one case as a transducer, of biomolecular events. Devices of these assemblies on solid supports that can operate in liquid solutions have been the focus. Polythiophenes, both semiconducting and conducting, is the class of materials that has been used in this work. The semiconducting polythiophenes have ionic side chains which makes them water soluble. This ionic side chain is capable of both forming electrostatic and hydrogen bonds, and when paired with the hydrophobic backbone of the polymer a great number of interactions with biomolecules are possible. The highly conducting polythiophene derivative PEDOT -PSS, (PEDOT) doped with ionic and water soluble PSS polyelectrolyte, was used as the conducting material in 3D-electrode. Both the semiconducting and conducting polymers described above forms hydrogels on solid supports if crosslinked with the appropriate ion, biomolecule or polymer. Evaluation of the CPEs, both with and without biomolecules, was performed in liquid, solid and hydrogel state using a number of techniques. This was done to understand how the CPEs behave when exposed to different buffer systems and various biomolecules.Hydrogels of conjugated polyelectrolytes combined with biomolecules are attractive as biosensors. The advantage with the hydrogel format is the high water content, the porous structure and the large capacity of binding molecules. High water content is important to preserve the biomolecules by providing the correct buffered environment. In this thesis we demonstrated a hydrogel of the highly conducting PEDOT -PSS polymer that was crosslinked on a solid support together with horseradish peroxidase (HRP) enzyme, forming an enzyme-enhanced electrode. Further studies of hydrogels were done using in situ quartz crystal microbalance with dissipation (QCM-D). POWT is a CPE withproperties well suited for biochip applications and readily forms hydrogels when exposed to water-based buffer solutions or biomolecule solutions. Detection ofcomplementary DNA and rejection of non-complementary DNA in a POWT hydrogel was demonstrated. The interaction between POWT and DNAoligonucleotides was also evaluated using fluorescence resonance energy transfer (FRET) in solution. Labeled DNA oligonucleotides with energy accepting or donating fluorophores allowed us to determine distance and binding stoichiometry in the non-covalent POWT-DNA complex.Patterning and anchoring of biomolecules and non-covalent assembled CPE-biomolecule complexes to a chip surface was studied; in the adsorbed state these complexes are hydrogels. Our novel method is based on the modification of the surface energy of a hydrophilic substrate surface using hydrophobic poly(dimethylsiloxane) (PDMS) elastomer stamp containing a relief pattern. Different conformations in biomolecules could be detected using fluorescence microscopy, where the CPEs acts as reporters and the PDMS modified substrates as discriminator. Also, excellent enzyme activity in patterned CPE/Horseradish peroxidase (HRP) enzyme was shown.Distances between the individual molecules in solid state devices of conjugated polymers can be small. In luminescence devices, such as light emitting diodes or fluorescence biosensors, there is a chance of interaction between conjugated molecules especially if more than one type of molecule is present. Quenching of the light and fluorescence energy transfer can occur and a simple approach to study this was developed.
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