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  • 1. Cardenas, M
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Lindh, L
    Salivary mucin MUC5B could be an important component of in vitro pellicles of human saliva: An in situ ellipsometry and atomic force microscopy study2007In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 4, p. 1149-1156Article in journal (Refereed)
    Abstract [en]

    This paper describes a combined investigation of the salivary and MUC5B films structure and topography in conditions similar to those found in the oral cavity in terms of ionic strength, pH, and protein concentration. AFM and ellipsometry were successfully used to give a detailed picture of the film structure and topography both on hydrophilic and on hydrophobic substrata. Regardless of the substrata, the salivary film can be described as having a two sublayer structure in which an inner dense layer is decorated by large aggregates. However, the shape and height of these larger aggregates largely depend on the type of substrata used. Additionally, we show that the adsorption of MUC5B is controlled by the type of substrata and the MUC5B film topography is similar to that of the larger aggregates present in the salivary films, especially on hydrophobic substrates. Therefore, we conclude that MUC5B is a major component in the salivary film when formed on hydrophobic substrates. Furthermore, we studied how resistant the salivary and MUC5B films are against elutability by buffer rinsing and addition of SDS solution. We conclude that the adsorbed proteins contain fractions with varying binding strengths to the two types of surfaces. Specifically, we have shown that the large MUC5B biomacromolecules on the hydrophobic substrates are especially resistant to both elution with buffer solution and SDS. Therefore, these large mucins can be responsible for the increased resistance of HWS films on hydrophobic substrates and can protect the intraoral surfaces against surface-active components present in oral health care products.

  • 2. Carlsson, F
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Arnebrant, T
    Malmsten, M
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Interactions between local anaesthetic agents and poly(N-isopropyl acrylamide) through phase behavior, surface tension, and adsorption measurements2001In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 233, p. 320-328Article in journal (Refereed)
    Abstract [en]

    he interaction between the local anaesthetic agents prilocaine and lidocaine, on one hand, and poly(N-isopropyl acrylamide) (pNIPAM), on the other, is investigated through studies of the polymer phase behavior and through surface tension and adsorption measurements. In particular, the cloud points (CP) for pNIPAM in the presence of lidocaine and prilocaine under different conditions were compared to the effects of electrolytes and alcohols. It was found that the electrolytes affect the CP of pNIPAM in a lyotropic manner, whereas alcohols depress the CP of pNIPAM in an alkyl chain length dependent way; i.e., the longer the chain, the larger the decrease in CP. Lidocaine and prilocaine affect the CP of pNIPAM in a pH-dependent manner. Below the p Ka of lidocaine and prilocaine, these cosolutes do not substantially affect the CP in the concentration range investigated, but rather behave analogous to simpler electrolytes. Above the p Ka, on the other hand, they strongly depress the CP already at low concentrations. In parallel, at low pH, the surface tension reduction due to lidocaine or prilocaine is marginal, whereas at high pH the surface tension is reduced considerably. Thus, the poor solubility of prilocaine and lidocaine at high pH causes these to become more surface active and simultaneously interact in a more pronounced way with pNIPAM. Furthermore, it was found from ellipsometry that an adsorbed pNIPAM layer contracts when lidocaine is added, presumably due to a lidocaine-pNIPAM interaction similar to that causing pNIPAM to phase separate. Analogous to this, it was demonstrated that an adsorbed pNIPAM layer shrinks and swells reversibly when the temperature is cycled above and beneath the CP.

  • 3.
    Choi, Jaeyeong
    et al.
    Lund University, Sweden.
    Wahlgren, Marie
    Lund University, Sweden.
    Ek, Vilhelm
    Swedish Orphan Biovitrum AB, Sweden.
    Elofsson, Ulla
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Fransson, Jonas
    Swedish Orphan Biovitrum AB, Sweden.
    Nilsson, Lars
    Lund University, Sweden.
    Terry, Ann
    Lund University, Sweden.
    Söderberg, Christopher
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Characterization of binding between model protein GA-Z and human serum albumin using asymmetrical flow field-flow fractionation and small angle X-ray scattering.2020In: PLOS ONE, E-ISSN 1932-6203, Vol. 15, no 11, article id e0242605Article in journal (Refereed)
    Abstract [en]

    Protein-based drugs often require targeted drug delivery for optimal therapy. A successful strategy to increase the circulation time of the protein in the blood is to link the therapeutic protein with an albumin-binding domain. In this work, we characterized such a protein-based drug, GA-Z. Using asymmetrical flow field-flow fractionation coupled with multi-angle light scattering (AF4-MALS) we investigated the GA-Z monomer-dimer equilibrium as well as the molar binding ratio of GA-Z to HSA. Using small angle X-ray scattering, we studied the structure of GA-Z as well as the complex between GA-Z and HSA. The results show that GA-Z is predominantly dimeric in solution at pH 7 and that it binds to monomeric as well as dimeric HSA. Furthermore, GA-Z binds to HSA both as a monomer and a dimer, and thus, it can be expected to stay bound also upon dilution following injection in the blood stream. The results from SAXS and binding studies indicate that the GA-Z dimer is formed between two target domains (Z-domains). The results also indicate that the binding of GA-Z to HSA does not affect the ratio between HSA dimers and monomers, and that no higher order oligomers of the complex are seen other than those containing dimers of GA-Z and dimers of HSA.

  • 4.
    Elofsson, Ulla
    et al.
    Lund University, Sweden.
    Dejmek, P.
    Lund University, Sweden.
    Paulsson, M. A.
    Lund University, Sweden.
    Heat-induced aggregation of β-lactoglobulin studied by dynamic light scattering1996In: International Dairy Journal, ISSN 0958-6946, E-ISSN 1879-0143, Vol. 6, no 4, p. 343-357Article in journal (Refereed)
    Abstract [en]

    The in situ heat-induced aggregation of commercial β-lactoglobulin as such, or after further purification, was followed to a z-average hydrodynamic diameter of 15-20 nm at 59-63°C by dynamic light scattering. In this temperature range, measurable increase of hydrodynamic diameter occurred after an apparent lag period, which was strongly dependent on heating temperature, pH and initial protein concentration. The changes in time scale of the aggregation process agreed with changes in amount of unfolded β- lactoglobulin, assuming a two-state model of the denaturation. The pH dependence reflected the midpoint unfolding temperature and not the sulphydryl group reactivity, suggesting that this reactivity was not rate limiting in the aggregation. The aggregation process was modelled numerically with Fuchs-Smoluchowski kinetics.

  • 5.
    Elofsson, Ulla
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Millqvist-Fureby, A
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Drying of probiotic micro-organisms in aqueous two-phase systems2000In: Minerva biotecnologica (Testo stampato), ISSN 1120-4826, E-ISSN 1827-160X, Vol. 12, p. 279-286Article in journal (Refereed)
    Abstract [en]

    Spray-drying has been investigated as a method for preparation of dry formulations of live bacteria with high viability and high cell density. The concept used in this study has been to disperse the bacteria in an aqueous polymer containing two-phase system (ATPS), compatible with the micro-organisms. The cells partition to one phase, which is separated from the other phase in a droplet dispersion or bi-continuous system. The exclusion of the dispersed phase and the bacteria from the particle surface is studied by ESCA (electron spectroscopy for chemical analysis), which gives an estimate of the molecular composition at the powders surface. A measure of the powder dissolution rate was obtained, this property was highly related to the molecular composition at the powder surface. The effect of additives was studied by adding disaccharides and proteins to the ATPS before drying. The probiotic bacteria Enterococcus faecium M74 and Lactobacillus plantarum have been used as model organisms for this study. The viability after drying and 5 weeks storage has been evaluated by plate counting and was found to be higher in the ATPS compared to when single phase polymer solutions were used as drying matrices. Comparisons were made with freeze-drying of the same systems and also the effect of cell status before the drying step has been evaluated.

  • 6.
    Elofsson, Ulla
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Millqvist-Fureby, Anna
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Stability of spray-dried protein-stabilized emulsions: Effects of different carbohydrate additives2003In: Food Colloids, Biopolymers and Materials / [ed] Eric Dickinson, Ton van Vliet, Royal Society of Chemistry, 2003, p. 265-274Chapter in book (Refereed)
  • 7.
    Elofsson, Ulla
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Millqvist-Fureby, Anna
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Gerde, Per
    Inhalation Sciences Sweden AB, Sweden.
    Pulmonary delivery of antimicrobial peptides2015In: ONdrugDelivery, ISSN 2049-145X, Vol. 57, p. 4-7Article in journal (Refereed)
    Abstract [en]

    Anna Fureby, PhD, Group Manager & Senior Scientist, Life Science, and Ulla Elofsson, PhD, Senior Scientist, both of SP Technical Research Institute of Sweden, and Per Gerde, PhD, Chief Scientific Officer, Inhalation Sciences Sweden, discuss the serious problem of antibiotic resistance and the potential role of antimicrobial peptides in the treatment of resistant bacterial strains. For pulmonary infections, optimising the formulation and delivery method is a crucial factor for success.

  • 8. Elversson, J
    et al.
    Millqvist-Fureby, Anna
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Alderborn, G
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet. RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Droplet and particle size relationship and shell thickness of inhalable lactose particles during spray drying2003In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 92, p. 900-910Article in journal (Refereed)
    Abstract [en]

    To find means of controlling the size and density of particles intended for inhalation the relationship between droplet and particle size during spray drying was investigated. Lactose solutions were atomized with a two-fluid nozzle and dried in a laboratory spray drier. The effects of nozzle orifice diameter, atomization airflow and feed concentration on droplet and particle size were examined. Mass median diameter of both droplets and particles were analyzed with laser diffraction. In addition, scanning electron microscopy and transmission electron microscopy were used for studies of particle shape and morphology. It was demonstrated that nozzle orifice diameter and airflow, but not feed concentration controlled the droplet size during atomization. Increasing droplet size increased particle size but the effect was also influenced by feed concentration. Particles from solutions of a low concentration (1% w/w) were smaller than those from higher concentrations (5-20% w/w). This may be partly explained by lower yields at higher feed concentrations, but may also be related to differences in drying rate. Spray-dried lactose solutions formed hollow particles, and it was suggested that the shell thickness of the particles increased with increasing feed concentration

  • 9. Hahn Berg, IC
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Joiner, A
    Malmsten, M
    Arnebrant, T
    Salivary protein adsorption onto hydroxyapatite and SDS-mediated elution studied by in situ ellipsometry2001In: Biofouling (Print), ISSN 0892-7014, E-ISSN 1029-2454, Vol. 17, p. 173-187Article in journal (Refereed)
    Abstract [en]

    Whole unstimulated saliva from two donors was investigated both with respect to adsorption characteristics and SDS-induced elutability. Salivary protein adsorption onto hydroxyapatite (HA) discs was studied by means of in situ ellipsometry in the concentration range 0.1-20% saliva. The adsorbed amounts on HA were found to be similar to those on silica, but the rates of adsorption were lower. Protein adsorption was virtually unaffected by the presence of Na+, whereas Ca2+ induced nucleation of calcium phosphate at the surface, the deposition rate being influenced by the pellicle age but not by the presence of saliva in bulk solution. The SDS elutability of adsorbed pellicles was determined on HA as well as on silica surfaces. Desorption from both surfaces was found to occur in the same SDS concentration range, although a residual layer was observed on HA. The slight net positive charge and lower charge density of HA as compared to the strongly negatively charged silica, may, at least partly, account for this observation by causing a reduction in the repulsive force between protein-surfactant complexes and the surface. Interindividual differences, observed in the adsorption as well as elution experiments, are thought to relate to the compositional differences observed by SDS-PAGE

  • 10. Halthur, TJ
    et al.
    Björklund, A
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Self-assembly/aggegation behavior, and adsorption of enamel matrix derivate protein to silica surfaces2006In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, p. 2227-2234Article in journal (Refereed)
    Abstract [en]

    Adsorption of the amelogein protein mixture enamel matrix derivate (EMD) to silica surfaces has been studied by in situ ellipsometry and quartz crystal microbalance with dissipation (QCM-D). The protein was found to adsorb as nanospheres in mono- or multilayers, depending on the concentration of “free” nanospheres available in solution. The concentration of free nanospheres is determined by the competitive processes of adsorption and rapid aggregation into microscopic particles, measured by dynamic light scattering (DLS). Multilayers could also be formed by sequential injections of fresh EMD solution. At higher temperature, an up to 6 times thicker gel-like film was formed on the substrate surface, and decreasing the pH lead to disruption of the multilayer/aggregate formation and a decreased amount adsorbed.

  • 11. Halthur, TJ
    et al.
    Claesson, PM
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Immobilization of enamel matrix derivate protein onto polypeptide multilayers. Comparative in situ measurements using ellipsometry, quartz crystal microbalance with dissipation, and dual polarization interferometry2006In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, p. 11065-11071Article in journal (Refereed)
    Abstract [en]

    The buildup of biodegradable poly(l-glutamic acid) (PGA) and poly(l-lysine) (PLL) multilayers on silica and titanium surfaces and the immobilization of Enamel Matrix Derivate protein (EMD) was followed by utilizing in situ using ellipsometry, Quartz Crystal Microbalance with Dissipation (QCM-D), and Dual Polarization Interferometry (DPI). The use of the relatively new DPI technique validated earlier published ellipsometry measurements of the PLL/PGA polypeptide films. The hydrophobic aggregating EMD protein was successfully immobilized both on top of as well as within the multilayer structures at pH 5.0. DPI measurements further indicated that the immobilization of EMD is influenced by the flow-pattern during adsorption. The formed polypeptide/EMD multilayer films are of interest since it is known that EMD is able to trigger cell response and induce biomineralization. The multilayer films thus have potential to be useful as bioactive and biodegradable coatings for future dental implants.

  • 12. Halthur, TJ
    et al.
    Claesson, PM
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Stability of polypeptide multilayers as studied by in situ ellipsometry: Effects of drying and post-buildup changes in temperature and pH2004In: Journal of The American Ceramic Society, ISSN 0002-7820, E-ISSN 1551-2916, Vol. 126, p. 17009-17015Article in journal (Refereed)
    Abstract [en]

    Polyelectrolyte Multilayers (PEM) of poly(L-glutamic acid) (PGA) and poly(L-lysine) (PLL) with an initial layer of polyethyleneimine (PEI) were built on silica and titanium surfaces using the Layer-by-Layer (LbL) technique. The stability of the film during drying/rewetting, temperature cycles and pH shifts was studied in situ by means of ellipsometry. The filmthickness was found to decrease significantly (approximately 70%) upon drying, but the original film-thickness was regained upon rewetting and the buildup could be continued. The thickness in dry state was found to be extremely sensitive to ambient humidity, needing several hours to equilibrate. Changes in temperature and pH was also found to influence the multilayer thickness, leading to swelling and de-swelling of as much as 8% and 10-20% respectively. The film does not necessarily regain its original thickness as the pH is shifted back, but instead shows clear signs of hysteresis.

  • 13. Halthur, TJ
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Multilayers of charged polypeptides as studied by in situ ellipsometry and quartz crystal microbalance with dissipation2004In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, p. 1739-1745Article in journal (Refereed)
    Abstract [en]

    The buildup of poly(L-glutamic acid) (PGA) and poly(L-lysine) (PLL) multilayers on silica and titanium surfaces, with and without an initial layer of polyethyleneimine (PEI), was investigated and characterized by means of in situ ellipsometry and quartz crystal microbalance with dissipation. A two-regime buildup was found in all systems, where the length of the first slow-growing regime is dependent on the structure of the initial layers. In the second fast-growing regime, the film thickness grows linearly while the mass increases more than linearly (close to exponentially) with the number of deposited layers. The film refractive indices as well as the water contents indicate that the film density changes as the multilayer film builds up. The change in film density was proposed to be due to polypeptides diffusing into the multilayer film as they attach. Furthermore, the use of PEI as the initial layer was found to induce a difference in the thickness increments for PGA and PLL.

  • 14. Johansson, JÅ
    et al.
    Halthur, T
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Herranen, M
    Söderberg, L
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Hilborn, J
    Build-up of collagen and hyaluronic acid polyelectrolyte multilayers2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, p. 1353-1359Article in journal (Refereed)
    Abstract [en]

    We have used a novel polyelectrolyte multilayer (PEM) coating consisting of the polyelectrolytes collagen and hyaluronic acid. The build-up by the layer-by-layer deposition technique is outlined by ex situ and in situ ellipsometric measurements. When collagen was added the thickness of the PEM was increased and the refractive index was decreased. Corresponding but opposite effects were noted when hyaluronic acid was added. These changes are considered to be explained by a diffusion mechanism. It was also found that the PEM layers were unstable at physiological pH. However, by crosslinking using N-(3-Di-methylaminopropyl)-N0-ethylcarbodiimide together with N-hydroxysuccinimide a stable PEM layer resulted. These tissue friendly PEM layers are expected to have a great impact in the design of artificial extra cellular matrices. Also, the insertion of fluorescence labels demonstrates the potential for incorporation of other functionalities

  • 15. Joiner, A
    et al.
    Muller, D
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Arnebrant, T
    Ellipsometry analysis of the in vitro adsorption of tea polyphenols onto salivary pellicles2004In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 112, p. 510-515Article in journal (Refereed)
  • 16. Joiner, A
    et al.
    Muller, D
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Malmsten, M
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Arnebrant, T
    Adsorption from black tea and red wine onto in vitro salivary pellicles studied by ellipsometry2003In: European Journal of Oral Sciences, ISSN 0909-8836, E-ISSN 1600-0722, Vol. 111, p. 417-422Article in journal (Refereed)
    Abstract [en]

    The adsorption of black tea and red wine components onto a pellicle-like protein layer formed in vitro by adsorption from whole unstimulated saliva on hydroxyapatite discs were studied by in situ ellipsometry. It was found that components from black tea readily adsorbed to the pellicle. Subsequent exposure to saliva led to further adsorption of salivary components to give an overall increase in the amounts adsorbed. The amounts adsorbed increased still further following a third tea and saliva exposure. Components of red wine gave significantly greater amounts of adsorption to the pellicle than black tea. The adsorption of components of black tea gave a concomitant increase in colour or stain as measured by a reflectance chromameter. In all cases, the black tea- and red wine-modified pellicles were not eluted by either phosphate buffer or sodium dodecyl sulphate (SDS) rinses. Thus, black tea and red wine components have been shown to have a profound effect on in vitro pellicle maturation, causing thickened layers of stained material to build up, which are not readily removed.

  • 17.
    Karalius, Antanas
    et al.
    KTH Royal Institute of Technology, Sweden.
    Zhang, Yang
    KTH Royal Institute of Technology, Sweden.
    Kravchenko, Oleksandr
    KTH Royal Institute of Technology, Sweden.
    Elofsson, Ulla
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Szabó, Zoltan
    KTH Royal Institute of Technology, Sweden.
    Yan, Mingdi
    KTH Royal Institute of Technology, Sweden; University of Massachusetts Lowell, US.
    Ramström, Olof
    KTH Royal Institute of Technology, Sweden, University of Massachusetts Lowell, US; Linnaeus University, Sweden.
    Formation and Out-of-Equilibrium, High/Low State Switching of a Nitroaldol Dynamer in Neutral Aqueous Media2020In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 59, no 9, p. 3434-3438Article in journal (Refereed)
    Abstract [en]

    The nitroaldol reaction is demonstrated as an efficient dynamic covalent reaction in phosphate buffers at neutral pH. Rapid equilibration was recorded with pyridine-based aldehydes, and dynamic oligomerization could be achieved, leading to nitroaldol dynamers of up to 17 repeating units. The dynamers were applied in a coherent stimuli-responsive molecular system in which larger dynamers transiently existed out-of-equilibrium in a neutral aqueous system rich in formaldehyde, controlled by nitromethane.

  • 18. Lundin, Maria
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Blomberg, Eva
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Rutland, Mark W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Adsorption of lysozyme, beta-casein and their layer-by-layer formation on hydrophilic surfaces: Effect of ionic strength2010In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 77, no 1, p. 1-11Article in journal (Refereed)
    Abstract [en]

    The adsorbed amount and layer structure of lysozyme, _x0002_-casein and mixed layers of the two proteins were studied on hydrophilic silica and quartz surfaces using the following techniques: ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D) and total internal reflection fluorescence (TIRF). Particular emphasis was put on the effect of solution ionic strength on the layer formation. Both lysozyme and _x0002_-casein showed a higher affinity for the silica surface when adsorbed from a solution of low ionic strength even though _x0002_-casein and silica are negatively charged at the pH used. No _x0002_-casein remained adsorbed after rinsing with a 150mMbuffer solution. The adsorbed amount of lysozyme on silica exceeded a monolayer coverage irrespective of the solution conditions and displayed a rigid structure. _x0002_-Casein forms more than a single layer on pre-adsorbed lysozyme; an inner flat layer and an outer layer with an extended structure, which largely desorbs on rinsing. The build-up through sequential adsorption of lysozyme and _x0002_-casein is favoured at intermediate and high ionic strength. The total adsorbed amount increased slightly with each deposition cycle and the mixed lysozyme/_x0002_-casein layers contain higher amounts of protein compared to those of pure lysozyme or _x0002_-casein. Sequential adsorption gives rise to a proteinaceous layer consisting of both lysozyme and _x0002_-casein. The protein layers are probably highly interpenetrated with no clear separation between them.

  • 19.
    Martínez, Claudia
    et al.
    Uppsala University, Sweden; University of Barcelona, Spain.
    Amery, Leanne
    AstraZeneca, UK.
    De Paoli, Giorgia
    University of Dundee, uk.
    Elofsson, Ulla
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Millqvist-Fureby, Anna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Kwok, Stanley
    AstraZeneca, USA.
    López-Cabezas, Carmen
    Hospital Clínic Barcelona, Spain.
    Rosenberger, Marika
    Sanofi-Aventis Deutschland GmbH, Germany.
    Schoenau, Christian
    Sanofi-Aventis Deutschland GmbH, Germany.
    Wahlgren, Marie
    Lund University,Sweden.
    Paulsson, Mattias
    Uppsala University, Sweden.
    Examination of the Protein Drug Supply Chain in a Swedish University Hospital: Focus on Handling Risks and Mitigation Measures2023In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017Article in journal (Refereed)
    Abstract [en]

    Protein drugs, such as monoclonal antibodies, have proved successful in treating cancer and immune system diseases. The structural complexity of these molecules requires careful handling to ensure integrity and stability of the drug. In this study, a failure mode and effects analysis was performed based on a Gemba Walk method in a Swedish University Hospital. The Gemba Walk is focused on pharmacists observing the actual supply process steps from distributor, pharmacy cleanroom to patient administration. Relevant protein drugs are chosen based on sales statistics within the hospital and the corresponding wards were observed. Further is the Double Diamond design method used to identify major risks and deliver mitigation strategies. The study identified potential stress factors such as temperature, shock by impact, shaking, vibration and light exposure. There were also risks associated with porters’ and healthcare professionals’ lack of awareness and access to information. These risk factors may cause loss of efficacy and quality of the protein drug, potentially leading to patient safety concerns. In this study, a simulation is also performed to list measures that theoretically should be in place to ensure the quality of the protein drug, for example validated and protocol-based compounding in cleanroom, training and validated transports. © 2023 The Authors

  • 20.
    Millqvist-Fureby, Anna
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Bergenståhl, B
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Surface composition of spray-dried milk protein-stabilised emulsions in relation to pre-heat treatment of proteins2001In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 21, p. 47-58Article in journal (Refereed)
    Abstract [en]

    Several important technical properties of spray-dried food powders depend on particle-liquid interactions (e.g. wettability, dispersability) and particle-particle interactions (e.g. flowability). It can be assumed that the chemical composition of the surface layer of the particles to a large extent determine these properties. The present study has been aimed to investigate the relation between the surface composition of spray-dried milk protein-stabilised emulsions and pre-heat treatment of the proteins. Solutions of WPC were heat-treated at low (60-90°C) and high (140°C) temperature and the degree of denaturation was determined, prior to the preparation of emulsions with rapeseed oil. The surface composition of the dry powders were established by using ESCA (electron spectroscopy of chemical analysis).The emulsions were characterised by droplet size distribution before spray drying and after dissolution of the powders. Also free fat extractions and estimations of wettability (dissolution rates) were performed. The powder surface coverage of protein decreased with increasing degree of protein denaturation before the emulsification, whereas the emulsion droplet size increased both before spray drying and after reconstitution of powders. The free fat extraction as well as the dissolution rate, whereof the latter decreased with increasing surface fat coverage, correlated well with the fat coverage of the powder surface.

  • 21. Mollmann, SH
    et al.
    Bukrinsky, JT
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Elversson, J
    Frokjaer, S
    Thalberg, K
    The stability of insulin in solid formulations containing melezitose and starch. Effects of processing and excipients2006In: Drug Development and Industrial Pharmacy, ISSN 0363-9045, E-ISSN 1520-5762, Vol. 32, no 6, p. 765-778Article in journal (Refereed)
    Abstract [en]

    Solid insulin formulations obtained by different methods of preparation were compared with respect to chemical stability and morphology. Spray- and freeze-drying, solution enhanced dispersion by supercritical fluids (SEDS) and precipitation into starch microspheres were the methods used for preparation of solid powders. The excipients applied were melezitose, starch and sodium taurocholate. The stability of the samples was evaluated after storage in open containers at 25°C and 30% RH for 6 months. All samples were amorphous after processing and storage as detected by XRD, except for the starch microspheres which were semi-crystalline. The spray- and freeze-dried samples containing melezitose and sodium taurocholate experienced a significant water uptake during storage, resulting in changes in morphology and disappearance of Tg. However, the chemical stability of these samples did not seem to be affected by the water uptake. Changes in morphology were not observed for the SEDS powders and the starch microspheres. The chemical stability of the samples was assessed by HPLC. In general, conventional spray and freeze drying resulted in samples with higher chemical stability compared to SEDS powders and starch microspheres. Nevertheless, the excipients applied were observed to be of major importance, and further optimization of the formulation as well as processing conditions may lead to slightly different conclusions.

  • 22. Mollmann, SH
    et al.
    Bukrinsky, JT
    Frokjaer, S
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Adsorption of human insulin and AspB28 insulin on a PTFE-like surface2005In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 286, p. 28-35Article in journal (Refereed)
    Abstract [en]

    The interactions of human insulin, Zn-free human insulin, and AspB28 insulin with a hydrophobic surface were studied by ellipsometry. All three insulin types investigated adsorbed with high affinity onto the hydrophobic surface, as the plateau of the adsorption isotherm, represented by the irreversible bound fraction, was reached at concentrations >10-3 mg/ml. The plateau values for human insulin and Zn-free human insulin could not be distinguished with statistical significance, whereas the plateau value for AspB28 insulin was lower than those for the two others, with an adsorbed amount corresponding to a monolayer of insulin monomers. The results observed may be explained by differences in self-association patterns of the insulin types or by enhanced charge repulsion between the AspB28 analog and the negatively charged surface

  • 23. Mollmann, SH
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Bukrinsky, JT
    Frokjaer, S
    Displacement of adsorbed insulin by Tween 80 monitored using total internal reflection fluorescence and ellipsometry2005In: Pharmaceutical research, ISSN 0724-8741, E-ISSN 1573-904X, Vol. 22, p. 1931-1941Article in journal (Refereed)
    Abstract [en]

    This study was conducted to investigate the mechanism of action in the displacement of adsorbed insulin from a hydrophobic surface by Tween 80 and of the competitive adsorption of the two species. Methods Total internal reflection fluorescence (TIRF) and ellipsometry were used as in situ methods to examine the processes taking place at hydrophobic model surfaces in the presence of insulin and Tween 80. Results TIRF studies showed that the displacement of insulin by Tween 80 could be fitted to a sigmoidal function, indicating a nucleation-dependent process. Furthermore, a linear dependence between the apparent rate constant and the logarithm of the Tween 80 concentration was found. Competitive adsorption from solution mixtures of insulin and Tween 80 indicated that insulin was adsorbed first, but subsequently displaced by the surfactant. This displacement proved also to be dependent on the concentration of Tween 80 in the mixture. Conclusions The results indicate that Tween 80 at concentrations above critical micelle concentration can be used to protect insulin against surface adsorption. The presence of a lag phase in the displacement at low surfactant concentration indicates that the mechanism of action for Tween 80 to reduce adsorption of insulin may be by competing for sites at the surface.

  • 24. Råvik, M
    et al.
    Cimander, C
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Veide, A
    A method for microbial cell surface fingerprinting based on surface plasmon resonance2007In: Journal of Biochemical and Biophysical Methods, ISSN 0165-022X, E-ISSN 1872-857X, Vol. 70, no 4, p. 595-604Article in journal (Refereed)
    Abstract [en]

    A method for cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different Esherichia coli mutants have been used as model cells, which were cultivated in shake flasks. Cell surface fingerprints were generated by registration of the interaction between the cell mutants and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences between some of the isolates were observed. Comparative measurements of physical property data are also included. A method for microbial cell surface fingerprinting using surface plasmon resonance (SPR) is suggested. Four different Escherichia coli mutants have been used as model cells. Cell surface fingerprints were generated by registration of the interaction between the cell mutants and four different surfaces, with different physical and chemical properties, when a cell suspension was flown over the surface. Significant differences in fingerprint pattern between some of the mutants were observed. At the same time, the physical properties of the cell surfaces were determined using microelectrophoresis, contact angle measurements and aqueous two-phase partitioning and compared to the SPR fingerprints. The generated cell surface fingerprints and the physical property data were evaluated with multivariate data analysis that showed that the cells were separated into individual groups in a similar way using principal component analysis plots (PCA)

  • 25. Sonesson, AW
    et al.
    Blom, H
    Hassler, K
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Callisen, TH
    Widengren, J
    Protein-surfactant interactions at hydrophobic interfaces studied with total internal reflection fluorescence correlation spectroscopy (TIR-FCS)2008In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 317, no 2, p. 449-457Article in journal (Refereed)
  • 26. Sonesson, AW
    et al.
    Brismar, H
    Callisen, TH
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Mobility of Thermomyces lanuginosus lipase on a trimyristin substrate surface2007In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 5, p. 2706-2713Article in journal (Refereed)
    Abstract [en]

    We have studied the mobility of active and inactive Thermomyces lanuginosus lipase (TLL) on a spin-coated trimyristin substrate surface using fluorescence recovery after photobleaching (FRAP) in a confocal microscopy setup. By photobleaching a circular spot of fluorescently labeled TLL adsorbed on a smooth trimyristin surface, both the diffusion coefficient D and the mobile fraction f could be quantified. FRAP was performed on surfaces with different surface density of lipase and as a function of time after adsorption. The data showed that the mobility of TLL was significantly higher on the trimyristin substrate surfaces compared to our previous studies on hydrophobic model surfaces. For both lipase variants, the diffusion decreased to similar rates at high relative surface density of lipase, suggesting that crowding effects are dominant with higher adsorbed amount of lipase. However, the diffusion coefficient at extrapolated infinite surface dilution, D0 , was higher for the active TLL compared to the inactive (D0 = 17.9 x10-11 cm2/s vs D0 = 4.1 x10-11 cm2/s, data for the first time interval after adsorption). Moreover, the diffusion decreased with time after adsorption, most evident for the active TLL. We explain the results by product inhibition, i.e., that the accumulation of negatively charged fatty acid products decreased the diffusion rate of active lipases with time. This was supported by sequential adsorption experiments, where the adsorbed amount under flow conditions was studied as a function of time after adsorption. A second injection of lipase led to a significantly lower increase in adsorbed amount when the trimyristin surface was pretreated with active TLL compared to pretreatment of inactive TLL.

  • 27. Sonesson, AW
    et al.
    Callisen, TH
    Brismar, H
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    A comparison between dual polarization interferometry (DPI) and surface plasmon resonance (SPR) for protein adsorption studies2007In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 54, p. 236-240Article in journal (Refereed)
    Abstract [en]

    This work was performed with the aim of comparing protein adsorption results obtained from the recently developed dual polarization interferometry (DPI) with the well-established surface plasmon resonance (SPR) technique. Both techniques use an evanescent field as the sensing element but completely different methods to calculate the adsorbed mass. As a test system we used adsorption of the lipase from Thermomyces lanuginosus (TLL) on C18 surfaces. The adsorbed amount calculated with both techniques is in good agreement, with both adsorption isotherms saturating at 1.30–1.35 mg/m2 at TLL concentrations of 1000nM and above. Therefore, this supports the use of both SPR and DPI as tools for studying protein adsorption, which is very important when comparing adsorption data obtained from the use different techniques. Due to the spot sensing in SPR, this technique is recommended for initial kinetic studies, whereas DPI is more accurate when the refractive index and thickness of the adsorbed layer is of more interest.

  • 28. Sonesson, AW
    et al.
    Callisen, TH
    Brismar, H
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Lipase surface diffusion studied by fluoroscence recovery after photobleaching2005In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, p. 11949-11956Article in journal (Refereed)
    Abstract [en]

    A Fluorescence Recovery after Photobleaching (FRAP) method to study protein diffusion on solid surfaces was developed using confocal microscopy. By photobleaching a rectangular area of the sample, fluorescence recovery could be analyzed as one-dimensional diffusion, leading to s simplified mathematical expressions for fitting the data. The method was tested by measuring bovine serum albumin (BSA) diffusion on glass, which led to a diffusion coefficient in good correspondence to earlier reports. Furthermore, the method was used to analyze the diffusion of a variant of Thermomyces lanuginosa lipase (TLL) on hydrophilic silica and silica methylated with dichlorodimethylsilane (DDS) or octadecyltrichlorosilane (OTS). Using ellipsometry data of TLL adsorption, fluorescence intensity could be calibrated to surface density of lipase, enabling measurements of the diffusion coefficient at different surface densities. The average diffusion coefficient was calculated in two time intervals after adsorption. Mobile fraction and diffusion coefficient was lowest on the OTS-surface, when extrapolated to infinite surface dilution. Moreover, the diffusion rate decreased with time on the hydrophobic surfaces. Our observations can be explained by the surface dependence on the distribution of orientations and conformations of adsorbed TLL, where the transition from the closed to the catalytically active open and more hydrophobic structure is important

  • 29. Sonesson, AW
    et al.
    Callisen, TH
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Brismar, H
    Adsorption and activity of Thermomyces lanuginosus lipase on hydrophobic and hydrophilic surfaces measured with dual polarization interferometry (DPI) and confocal microscopy2008In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 61, p. 208-215Article in journal (Refereed)
    Abstract [en]

    The adsorption and activity of Thermomyces lanuginosus lipase (TLL) was measured with dual polarization interferometry (DPI) and confocal microscopy at a hydrophilic and hydrophobic surface. In the adsorption isotherms, it was evident that TLL both had higher affinity for the hydrophobic surface and adsorbed to a higher adsorbed amount (1.90 mg/m2) compared to the hydrophilic surface (1.40–1.50 mg/m2). The thickness of the adsorbed layer was constant (not, vert, similar3.5 nm) on both surfaces at an adsorbed amount >1.0 mg/m2, but decreased on the hydrophilic surface at lower surface coverage, which might be explained by partially unfolding of the TLL structure. However, a linear dependence of the refractive index of the adsorbed layer on adsorbed amount of TLL on C18 surfaces indicated that the structure of TLL was similar at low and high surface coverage. The activity of adsorbed TLL was measured towards carboxyfluorescein diacetate (CFDA) in solution, which upon lipase activity formed a fluorescent product. The surface fluorescence intensity increase was measured in a confocal microscope as a function of time after lipase adsorption. It was evident that TLL was more active on the hydrophilic surface, which suggested that a larger fraction of adsorbed TLL molecules were oriented with the active site facing the solution compared to the hydrophobic surface. Moreover, most of the activity remained when the TLL surface coverage decreased. Earlier reports on TLL surface mobility on the same surfaces have found that the lateral diffusion was highest on hydrophilic surfaces and at low surface coverage of TLL. Hence, a high lateral mobility might lead to a longer exposure time of the active site towards solution, thereby increasing the activity against a water-soluble substrate.

  • 30. Sonesson, AW
    et al.
    Callisen, TH
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Brismar, H
    Imaging the detergency of single cotton fibers with confocal microscopy: the effect of surfactants and lipases2007In: Journal of Surfactants and Detergents (JSD), ISSN 1097-3958, E-ISSN 1558-9293, Vol. 10, no 4, p. 211-218Article in journal (Refereed)
    Abstract [en]

    Detergency mechanisms of lipids from single cotton fibers were visualized by means of confocal laser scanning microscopy (CLSM). Fibers were soiled with different types of lipids: olive oil, lard and tri-C10, and subsequently stained with the fluorescent probe Nile Red. A surfactant composition of 300 μM C12E6/LAS (1:2 mol%) was used to mimic the surfactants used in a common washing solution. It was evident from the captured image series that the different kinds of soiling were removed by different mechanisms by the surfactants, depending on the fluidity of the lipid. Roll-up was the main mechanism when removing olive oil, whereas emulsification (necking) and/or solubilization were observed in the removal of lard and tri-C10. Only 20–25% of the olive oil remained after treatment with surfactants, which was much less compared to the solid fats where roughly 50% remained at end of treatment. The effect of adding lipases to the detergent formulation was clearly seen, both by an apparently higher rate of removal of olive oil but also using double injection when removing lard. A first injection of only surfactants removed a certain part of the lard as emulsion droplets stuck onto the fiber. A second injection of both lipases and surfactants was able to remove some of the preformed emulsion particles and reduce the overall remaining lard content on the cotton fiber.

  • 31. Sonesson, AW
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Brismar, H
    Callisen, TH
    Adsorption and mobility of a lipase at a hydrophobic surface in the presence of surfactants2006In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, p. 5810-5817Article in journal (Refereed)
    Abstract [en]

    With the aim of being able to manipulate the processes involved in interfacial catalysis, we have studied the effects of a mixture of nonionic/anionic surfactants, C12E6/LAS (1:2 mol %), on the adsorption and surface mobility of a lipase obtained from Thermomyces lanuginosus (TLL). Surface plasmon resonance (SPR) and ellipsometry were used to analyze the competitive adsorption process between surfactants and TLL onto hydrophobic model surfaces intended to mimic an oily substrate for the lipase. We obtained the surface diffusion coefficient of a fluorescently labeled TLL variant on silica silanized with octadecyltrichlorosilane (OTS) by fluorescence recovery after photobleaching (FRAP) on a confocal laser scanning microscope. By means of ellipsometry we calibrated the fluorescence intensity with the surface density of the lipase. The TLL diffusion was measured at different surface densities of the enzyme and at two time intervals after coadsorption with different concentrations of C12E6/LAS. The surfactant concentrations were chosen to represent concentrations below the critical micelle concentration (CMC), in the CMC region, and above the CMC. The apparent TLL surface diffusion was extrapolated to infinite surface dilution, D0. We found that the presence of surfactants strongly modulated the surface mobility of TLL: with D0 = 0.8 x 10-11 cm2/s without surfactants and D0 = 13.1 x 10-11 cm2/s with surfactants above the CMC. The increase in lipase mobility on passing the CMC was also accompanied by a 2-fold increase in the mobile fraction of TLL. SPR analysis revealed that surface bound TLL was displaced by C12E6/LAS in a concentration-dependent manner, suggesting that the observed increase in surface mobility imparts bulk-mediated diffusion and so-called rebinding of TLL to the surface. Our combined results on lipase/surfactant competitive adsorption and lipase surface mobility show how surfactants may play an important role in regulating interfacial catalysis from physiological digestion to technical applications such as detergency.

  • 32. Sonesson, AW
    et al.
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Callisen, TH
    Brismar, H
    Tracking single lipase molecules on a trimyristin substrate surface using quantum dots2007In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 16, p. 8352-8356Article in journal (Refereed)
    Abstract [en]

    : The mobility of single lipase molecules has been analyzed using single molecule tracking on a trimyristin substrate surface. This was achieved by conjugating lipases to quantum dots and imaging on spin-coated trimyristin surfaces by means of confocal laser scanning microscopy. Image series of single lipase molecules were collected, and the diffusion coefficient was quantified by analyzing the mean square displacement of the calculated trajectories. During no-flow conditions, the lipase diffusion coefficient was (8.0 +/- 5.0) x 10(-10) cm(2)/s. The trajectories had a "bead on a string" appearance, with the lipase molecule restricted in certain regions of the surface and then migrating to another region where the restricted diffusion continued. This gave rise to clusters in the trajectories. When a flow was applied to the system, the total distance and average step length between the clusters increased, but the restricted diffusion in the cluster regions was unaffected. This can be explained by the lipase operating in two different modes on the surface. In the cluster regions, the lipase is likely oriented with the active site toward the surface and hydrolyzes the substrate. Between these regions, a diffusion process is proposed where the lipase is in contact with the surface but affected by the external flow

  • 33. Svendsen, IE
    et al.
    Lindh, L
    Elofsson, Ulla
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, YKI – Ytkemiska institutet.
    Arnebrant, T
    Studies on the exchange of early pellicle proteins by mucin and whole saliva2008In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 321, no 1, p. 52-59Article in journal (Refereed)
    Abstract [en]

    Adsorption of small pellicle proteins statherin or proline-rich protein 1 (PRP1), respectively, and subsequent adsorption of human whole saliva (HWS) or salivary mucin MUC5B, respectively, was studied using ellipsometry and total internal reflectance fluorescence. Differences in elution (using sodium dodecyl sulphate (SDS) solutions) between mixed and single protein films were also investigated. On both hydrophilic and hydrophobized surfaces HWS and MUC5B were found to adsorb to pre-adsorbed layers of statherin and PRP1, respectively. Statherin adsorption on both substrate types showed no or minor exchange by HWS or MUC5B and no change in SDS elution between mixed and single protein films. Small amounts of PRP1 were exchanged by HWS on both surface types and the SDS elutable fractions were similar or larger for mixed films compared to single protein films. PRP1 and MUC5B in sequence showed minor exchange of PRP1 on hydrophilic surfaces, while no exchange could be established on hydrophobized substrates. SDS elutable fractions decreased for PRP1 and MUC5B mixed films compared to single protein films. In conclusion, minor amounts of statherin and PRP1 are exchanged during the time course of the experiments, which indicates that these proteins may to a large extent remain incorporated in the pellicle.

  • 34.
    Västberg, Amanda
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development. Lund University, Sweden.
    Bolinsson, Hans
    Lund University, Sweden.
    Leeman, Mats
    Solve Research & Consultancy, Sweden.
    Nilsson, Lars
    Lund University, Sweden.
    Nylander, Tommy
    Lund University, Sweden.
    Sejwal, Kushal
    Vironova AB, Sweden.
    Sintorn, Ida-Maria
    Vironova AB, Sweden.
    Lidayová, Kristina
    Vironova AB, Sweden.
    Sjögren, Helen
    Ferring Pharmaceuticals, Denmark.
    Wahlgren, Maria
    Lund University, Sweden.
    Elofsson, Ulla
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Investigating thermally induced aggregation of Somatropin- new insights using orthogonal techniques2023In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 637, article id 122829Article in journal (Refereed)
    Abstract [en]

    Three orthogonal techniques were used to provide new insights into thermally induced aggregation of the therapeutic protein Somatropin at pH 5.8 and 7.0. The techniques were Dynamic Light Scattering (DLS), Asymmetric Flow-Field Flow-Fractionation (AF4), and the TEM-based analysis system MiniTEM™. In addition, Differential Scanning Calorimetry (DSC) was used to study the thermal unfolding and stability. DSC and DLS were used to explain the initial aggregation process and aggregation rate at the two pH values. The results suggest that less electrostatic stabilization seems to be the main reason for the faster initial aggregation at pH 5.8, i.e., closer to the isoelectric point of Somatropin. AF4 and MiniTEM were used to investigate the aggregation pathway further. Combining the results allowed us to demonstrate Somatropin's thermal aggregation pathway at pH 7.0. The growth of the aggregates appears to follow two steps. Smaller elongated aggregates are formed in the first step, possibly initiated by partly unfolded species. In the second step, occurring during longer heating, the smaller aggregates assemble into larger aggregates with more complex structures. © 2023 The Author(s)

  • 35.
    Åkerlund, Thomas
    et al.
    Public Health Agency of Sweden, Sweden.
    Zakikhany, Katherina
    Public Health Agency of Sweden, Sweden.
    Löfström, Charlotta
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Lindmark, Evelina
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Källberg, Henrik
    Public Health Agency of Sweden, Sweden.
    Elofsson, Ulla
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Cederbrant, Karin
    RISE Research Institutes of Sweden.
    Nygren, Erik
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Kallin, Anders
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Lagerqvist, Nina
    Public Health Agency of Sweden, Sweden.
    Nilsson, Peter
    KTH Royal Institute of Technology, Sweden.
    Hober, Sophia
    KTH Royal Institute of Technology, Sweden.
    Ridderstad Wollberg, Anna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Chemical Process and Pharmaceutical Development.
    Björndal, Åsa Szekely
    Public Health Agency of Sweden, Sweden.
    Stable IgG-antibody levels in patients with mild SARS-CoV-2 infection2021In: MedrxivArticle in journal (Refereed)
    Abstract [en]

    More knowledge regarding persistence of antibody response to SARS-CoV-2 infections in the general population with mild symptoms is needed. We measured and compared levels of SARS CoV-2 spike- and nucleocapsid-specific IgG-antibodies in serum samples from 145 laboratory confirmed COVID-19 cases and 324 non-cases. The IgG-antibody levels against the spike protein in cases were stable over the time-period studied (14 to 256 days), while antibody levels against the nucleocapsid protein decreased over time

1 - 35 of 35
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