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- Andersson, Margaretha, et al.
(författare)
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Surface attachment of nanoparticles using oligonucleotides
- 2004
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Ingår i: Colloids and Surfaces B: Biointerfaces. ; 34, s. 165-171
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal polymer particles are widely used in a variety of applications ranging from chromatography to surface modified bioreactors in protein arrays. In the present study, surface attachment of polystyrene particles to a polystyrene substrate has been p
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| 5. |
- Ekeroth, Johan, 1974-
(författare)
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Phosphorylated Monomolecular Layers : Design, Synthesis, Characterization and Application
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the design, synthesis and characterization of organo-phosphatemonomolecular layers, so called self-assembled monolayers, using the strategy of linking organosulfur substances to a gold surface. Moreover there is also a paper included, which describes the development of synthetic pathways to various phospholipids, for which I have developed an interest in later projects.For the first study of the properties of phosphates, and also for concomitant application of developed systems, analogues of the amino acids serine, threonine and tyrosine, phosphorylated and non-phosphorylated, were synthesized. 16-Mercaptohexadecanamide based analogues were characterized as monolayers and large polar and charge effects were observed, introduced by the phosphate. Problems were, however, encountered as a post modification of phosphates was applied and a disordering of the monolayers observed. Moreover there were no expected effects observable upon interaction with Ca2+ and Mg2+.Based on the conclusions from the first study 3-mercaptopropionamide based analogues were used instead. Characterization of the analogues including counter ion exchange (H+,Na+, Ca2+ and Mg2+) revealed large electronic and possible structural differences depending on the counter ion.Again the charge and polar effects induced by the phosphate were investigated, and the study was also extended to interaction of the phosphate with Ca2+ and Mg2+. Strong effects were observed, which were also dependent on the ion concentration within a significant range. The polarity and charge properties of the phosphate layer were thus found to be variable.In the fourth study an additional Ca2+ and Mg2+ sensitive system was applied in combination with the phosphate surface. Phosphate surface/phospholipid vesicle interactions were studied under different conditions of Mg2+ (Ca2+) treatment. For comparison, the corresponding hydroxyl and sulphate surfaces were included and also the most well characterized surface concerning phospholipid vesicle interaction, SiO2. Most importantly, supported phospholipid bilayer (SPB) formation was found to be inducible on both the phosphate and sulphate surfaces, however at defined conditions of Mg2+ (Ca2+) treatment and concentration. The conclusion is that the processes of phospholipid vesicle adsorption and SPB formation are largely dependent on vesicle/surface interaction and vesicle stability.The last paper included in this thesis is a synthetic method development aimed at easy preparations of various phospholipid derivatives. In the future these methods could be used for synthesis of functionalized lipids and aid in the development of models mimicking biological systems such as artificial cell membranes.
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| 7. |
- Karlsson, Marjam, 1975-
(författare)
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Nano-porous Alumina, a Potential Bone Implant Coating
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes a method of growing a highly adherent nano-porous alumina coating on titanium implant materials, a design which might be useful in hard tissue replacement. Alumina layers were formed by anodisation of aluminium, which had been deposited on titanium and titanium alloys by electron beam evaporation. Mechanical testing showed the coatings’ shear and tensile strength to be ~20MPa and ~10MPa respectively. Human osteoblasts were cultured on purchased membranes, produced in the same way with similar characteristics as the coating mentioned above. Cell viability, proliferation and phenotype were assessed by measuring redox reactions, DNA, tritiated thymidine incorporation and alkaline phosphatase production. Results showed normal osteoblastic growth patterns with increasing cell numbers the first two weeks after which cell growth decreased and alkaline phosphatase production increased, indicating that osteoblastic phenotype was retained on the alumina. Flattened cell morphology with filipodia attached to the pores of the material was seen. Implants frequently trigger inflammatory responses due to accumulation and activation of cells such as polymorphonuclear granulocytes (PMN), also called neutrophils. Activation and morphology of human PMN in response to nano-porous alumina with two pore sizes (20 and 200 nm) was investigated by luminol-amplified chemiluminescence, granule enzyme deposition measurement, optical and scanning electron microscopy. Activation was observed on both membrane types, however less pronounced on the 200 nm alumina. For both membranes a decrease in activation was seen after coating with fibrinogen, collagen I and serum (more pronounced for the two latter). On fibrinogen-coated alumina many flattened cells were observed, indicating frustrated phagocytosis. Finally when culturing osteoblasts on non-coated and collagen-coated membranes (after exposure to PMN) many more cells had established on the protein-coated surface after 24 h. The overall results indicate that it might be possible to produce a novel bone implant coating by anodisation of aluminium deposited on titanium and that this material will support osteoblast adhesion and proliferation. Furthermore neutrophil activation can be suppressed when coating the alumina with collagen I, which is beneficial considering the fact that this protein also is essential for bone formation.
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| 8. |
- Lindholm, Johan, 1974-
(författare)
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Development and Validation of HPLC Methods for Analytical and Preparative Purposes
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the development and validation of high performance liquid chromatography (HPLC) methods aimed for two industrially important areas: (i) analysis of biotechnological synthesis and (ii) determination of adsorption isotherm parameters. There is today a lack of detailed recommendations for analytical procedures in the field of biotechnological production of drugs. Therefore, guidelines were given for analytical development and validation in this field; the production of 9α-hydroxyprogesterone was used as model. In addition, a rapid method using HPLC coupled with diode-array-detection (DAD) and mass spectrometry (MS), was developed for the preliminary identification and quantification of the product. In addition, requirements and recommendations were developed for the selection of the internal standard and for its inclusion in the process liquid. By using this approach the precision and accuracy of the quantitative method were considerably improved. Preparative chromatography is a powerful separation method for the purification of pure compounds from more or less complex sample mixtures. One such mixture can be the process liquid from a fermentation, another example can be a racemic mixture of compounds whose enantiomeric constituents must be isolated. Computer-assisted modeling can be used to optimize preparative chromatography. However, competitive adsorption isotherm parameters are required as input data for the computer simulations. In this thesis, a new injection technique, based on a firm theoretical basis, was developed for the peak perturbation (PP) method allowing the determination of binary competitive adsorption isotherm parameters from a broad concentration range. With the new method the determination of adsorption isotherm parameters from a quaternary mixture could be done for the first time. The profiles simulated with these parameters showed excellent agreement with the corresponding experimental profiles, validating the accuracy of the adsorption isotherm parameters derived by the new method.
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| 9. |
- Lindholm, Johan, et al.
(författare)
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Use of liquid chromatography-diode-array detection and mass spectrometry for rapid product identification in biotechnological synthesis of a hydroxyprogesterone
- 2003
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Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 992:1-2, s. 85-100
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Tidskriftsartikel (refereegranskat)abstract
- In exploratory scale biotechnological process development, the product must be rapidly identified although a reference compound may not always be available. LC-diode-array detection and MS were used for this purpose in a process producing 9alpha-hydroxyprogesterone from progesterone as substrate. The electrospray ionization mass spectrometer was combined with an ion trap mass spectrometer for the second generation MS. The preliminary identification, which could be carried out within the course of a day, confirmed that the product was a hydroxyprogesterone. The final identification step, which was much more material intensive and hence time consuming, involved a two-step preparative separation to yield quantities necessary for definitive product identification based on 1H- and 13C NMR.
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| 12. |
- Webb, Ken, et al.
(författare)
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A novel surfactant-based immobilization method for varying substrate-bound fibronectin
- 2001
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Ingår i: JOURNAL OF BIOMEDICAL MATERIALS RESEARCH. - : JOHN WILEY & SONS INC. - 0021-9304. ; 54:4, s. 509-518
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Tidskriftsartikel (refereegranskat)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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