| 1. |
- Borde, Annika, 1979, et al.
(författare)
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Increased water transport in PDMS silicone films by addition of excipients
- 2012
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1742-7061 .- 1878-7568. ; 8:2, s. 579-588
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Tidskriftsartikel (refereegranskat)abstract
- The development of new adhesive wound care products intended for an application over a prolonged time requires good water transporting properties of the adhesive for the maintenance of a suitable environment around the wound. The ability of polydimethylsiloxane (PDMS)-based silicone films to transport water has led to its use in skin pressure-sensitive adhesives and it would be advantageous to find ways for controlling or increasing water transport across PDMS films in order to be able to develop improved skin adhesives. In this study we present a way to increase water transport in such films by the addition of hydrophilic excipients. Three hydrophilic additives, highly water-soluble sucrose and the two superabsorbent polymers (SAP) Carbopol® and Pemulen™, were investigated. The effect of the excipients was characterized by water transport studies, swelling tests, scanning electron microscopy imaging and confocal microscopy. The cross-linked polymers, primarily Pemulen™, were efficient water transport enhancers, whereas sucrose did not show any effect. The effect of the additives seemed to correlate with their water binding capacity. For SAPs the formation of a percolating structure by swollen polymer was also suggested, which enhances water penetration by the higher volume fraction of areas with a higher diffusion constant (swollen SAP), leading to a faster transport through the entire film. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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| 2. |
- Larsson, Mikael, 1982, et al.
(författare)
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Evaluation of Carboxymethyl-Hexanoyl Chitosan as a Protein Nanocarrier
- 2013
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Ingår i: Nanomaterials and Nanotechnology. - : SAGE Publications. - 1847-9804. ; 3:1, s. Art. no. 7-
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Tidskriftsartikel (refereegranskat)abstract
- Carboxymethyl‐hexanoyl chitosan (CHC) has the ability to self‐assemble into nanocapsules in anaqueous solution and it has recently shown potentialin numerous biomedical applications. Here weinvestigate the protein loading efficiency and release,as well as the structural properties of CHC proteinnanocarriers. Bovine serum albumin (BSA) or itschromophore labelled version, fluorescein‐BSA, wasused as a model protein and the loading wasperformed with a simple mixing of pre‐formednanocapsules and protein. Dynamic light scatteringand zeta potential analysis revealed that proteinloaded nanocarriers with high positive zeta potentialwere formed. The protein loaded nanocarriersdisplayed a loading efficiency of 75% and a very slowprotein release. In summary, our results highlight thepotential of CHC as a protein nanocarrier, but alsoindicate that protein‐CHC interactions need to beconsidered in protein containing CHC formulationswhere protein release is not the main function.
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| 3. |
- Borde, Annika, 1979, et al.
(författare)
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Effect of protein release rates from tablet formulations on the immune response after sublingual immunization
- 2012
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 47:4, s. 695-700
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Tidskriftsartikel (refereegranskat)abstract
- Dry vaccine formulations for sublingual administration would provide great advantages for public health use, especially in developing countries, since they are easy to administer and might also have improved stability properties. This study investigates the influence of protein release rate from mucoadhesive twolayer tablets on the elicited antibody responses after sublingual immunization. Two fast release tablets, one based on a mixture of lactose and microcrystalline cellulose (MCC) and one protein coated ethylcellulose (EC) tablet, and three hydrophilic matrix tablets with extended release (ER) properties based on HPMC 90 SH 100000 or Carbopol® 974-P NF were tested. The in vitro release profiles of the model protein ovalbumin (OVA) from these tablets were characterized and correlated to the in vivo potential of the tablets to induce an immune response after sublingual immunization in BALB/c mice. It could be concluded that a tablet with fast protein release elicits antibody titres not significantly different from titres obtained with OVA in solution, whereas low immune responses were observed with a slow release of OVA from the ER formulations. Thus, an ER tablet seems not favorable for vaccine delivery to the sublingual mucosa. Thus, we can present a fast releasing tablet formulation with attractive features for sublingual immunization, whereas the use of ER formulations for sublingual vaccination has to be investigated more in detail.
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| 4. |
- Borde, Annika, 1979, et al.
(författare)
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Osmotic-driven mass transport of water: Impact on the adhesiveness of hydrophilic polymers
- 2009
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 341:2, s. 255-260
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Tidskriftsartikel (refereegranskat)abstract
- Adhesion is an important property for the functionality of many medical devices. One reason for the development of adhesive forces is dehydration caused by mass transport of water. Osmotic pressure is one main driving force for mass transport and the correlation between osmotic pressure and adhesive force has not been studied yet, which was the aim of the present study. A model system was used where a Carbopol tablet was lowered onto a 1% (w/w) agarose gel. The force required to detach the tablet (adhesive force) and the weight gain of the tablet (as a measure of transported water) were determined. Sodium chloride and mannitol were added to the agarose gel to decrease the osmotic pressure difference between the agarose gel and the partially hydrated Carbopol tablet. This resulted in a decrease of both mass transport and adhesive force. In addition, experiments with restricted water transport within the agarose gel were performed by preparing gels with different agarose concentrations. An increase of the agarose concentration resulted in decreased water transport and higher adhesive forces. Hence, the results confirmed our hypothesis that osmotic-driven mass transport and restricted mass transport of water correlate very well with the adhesive force.
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| 5. |
- Borde, Annika, 1979, et al.
(författare)
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Preparation and evaluation of a freeze-dried oral killed cholera vaccine formulation
- 2011
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 79:3, s. 508-518
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Tidskriftsartikel (refereegranskat)abstract
- Different oral liquid cholera vaccines have proved to be safe and effective, but their formulations present problems for use in low-income countries, since large package volumes have to be transported and cold chain maintenance is required. A solid state formulation would here be more advantageous, and consequently, the possibility to develop a dry cholera vaccine formulation by freeze-drying was investigated. The ability of sucrose, trehalose and mannitol to provide process stabilization during freeze-drying was tested on a formalin-killed whole-cell Vibrio cholerae model vaccine. A matrix of sucrose or trehalose prevented bacterial aggregation, preserved cell morphology and maintained practically completely the protective lipopolysaccharide (LPS) antigen on the cell surface and its reactivity with specific antibody in vitro. After reconstitution, this formulation also retained the capacity to elicit a strong serum and gut mucosal anti-LPS antibody response in orally immunized mice, as compared to the corresponding liquid vaccine formulation. The full preservation of the in vivo immunogenicity was also maintained when the internationally widely licensed oral cholera vaccine Dukoral (TM), which comprises a cocktail of inactivated V. cholerae together with cholera toxin B-subunit (CTB), was freeze-dried using sucrose for stabilization. Thus, we present a process generating a dry oral inactivated whole-cell cholera vaccine formulation with attractive features for public health use in cholera-afflicted settings.
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| 6. |
- Borde, Annika, 1979, et al.
(författare)
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Preparation and preclinical evaluation of a freeze-dried formulation of a novel combined multivalent whole-cell/B-subunit oral vaccine against enterotoxigenic Escherichia coli diarrhea
- 2016
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Ingår i: European Journal of Pharmaceutics and Biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 108, s. 18-24
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Tidskriftsartikel (refereegranskat)abstract
- A promising liquid killed multivalent whole-cell plus enterotoxin B-subunit oral vaccine against enterotoxigenic Escherichia coli (ETEC), the primary cause of diarrhea among children in low-income countries and travelers to these areas, has recently been developed and tested in preclinical and phase-I and phase-II clinical studies. The vaccine contains killed E. coli bacteria over-expressing the main ETEC colonization factors (CFs) CFA/I, CS3, C5 and C6, and a recombinant enterotoxin B subunit protein (LCTBA) given together with a recently developed enterotoxin-derived adjuvant, dmLT. A dry-powder vaccine formulation should be advantageous especially for use in low-income countries. Here we describe a method to produce a dry-powder formulation by freeze-drying of the vaccine using inulin as stabilizer. Although not completely preventing aggregation of bacteria during freeze-drying, the stabilizer provided both improved overall bacterial morphology and almost complete recovery of the CF and B subunit antigens. Most importantly, oral-intragastric immunization of mice with the freeze-dried vaccine together with dmLT adjuvant elicited strong intestinal mucosal and serum antibody responses against all vaccine antigens, which were comparable to those achieved with the liquid vaccine. Our results indicate the feasibility to use freeze-drying with inulin as stabilizer for preparing a dry-powder formulation of the novel ETEC vaccine with retained oral-mucosal immunogenicity compared to the liquid formulation. © 2016 Elsevier B.V.
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| 7. |
- Brackmann, Christian, 1973, et al.
(författare)
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CARS microscopy of lipid stores in yeast: the impact of nutritional state and genetic background
- 2009
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 40:7, s. 748-756
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a protocol for sub-micrometer resolved and chemically specific imaging of lipid storage in vivo employing coherent anti-Stokes Raman scattering (CARS) microscopy of one of the most important model organisms Saccharomyces cerevisiae - the yeast cell. By probing the carbon-hydrogen vibration using the nonlinear process of CARS, lipid droplets in the yeast cells clearly appear, as confirmed by comparative studies on relevant labeled organelles using two-photon fluorescence microscopy. From the images, unique quantitative data can be deduced with high three-dimensional resolution, such as the volume, shape, number, and intracellular location of the neutral lipid stores. We exemplify the strength and usability of the method for two cases: the impact on lipid storage of the nutritional condition (starvation and type of carbon source available) as well as of genetic modification of two fundamental metabolic regulation pathways involving carbohydrate and lipid storage (BCY1 and DGA1, LRO1, ARE1/2 deletions), respectively. While the impact of carbon source on the total cellular lipid volume was minimal, long-term starvation induces a significant accumulation of lipid droplets. We also confirm that the lipid-storage-deficient mutant is indeed unable to synthesize lipid droplets, and that the inability of the bcy1-mutant to store carbohydrates is compensated by a two-fold increase in stored neutral lipids. We note that there is a significant cell-to-cell variability in neutral lipid storage in general, i.e. that there is a correspondence to the noise found for gene expression also in lipidomics. Copyright (C) 2009 John Wiley & Sons, Ltd.
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| 8. |
- Carlsson, Nils, 1978, et al.
(författare)
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Quantification of protein concentration by the Bradford method in the presence of pharmaceutical polymers
- 2011
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 411:1, s. 116-121
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Tidskriftsartikel (refereegranskat)abstract
- We investigated how the Bradford assay for measurements of protein released from a drug formulation may be affected by a concomitant release of a pharmaceutical polymer used to formulate the protein delivery device. The main result is that polymer-caused perturbations of the Coomassie dye absorbance at the Bradford monitoring wavelength (595 nm) can be identified and corrected by recording absorptionspectra in the region of 350–850 mm. The pharmaceutical polymers Carbopol and chitosan illustrate two potential types of perturbations in the Bradford assay, whereas the third polymer, hydroxypropylmethylcellulose (HPMC), acts as a nonperturbing control. Carbopol increases the apparent absorbance at 595 nm because the polymer aggregates at the low pH of the Bradford protocol, causing a turbidity contribution that can be corrected quantitatively at 595 nm by measuring the sample absorbance at 850 nm outside the dye absorption band. Chitosan is a cationic polymer under Bradford conditions and interacts directly with the anionic Coomassie dye and perturbs its absorption spectrum, including 595 nm. In this case, the Bradford method remains useful if the polymer concentration is known but should be used with caution in release studies where the polymer concentration may vary and needs to be measured independently.
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| 9. |
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| 10. |
- Kirchner, Kristin, 1987, et al.
(författare)
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Covariance structure of parabolic stochastic partial differential equations with multiplicative Lévy noise
- 2017
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Ingår i: Journal of Differential Equations. - : Elsevier BV. - 1090-2732 .- 0022-0396. ; 262:12, s. 5896-5927
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Tidskriftsartikel (refereegranskat)abstract
- The characterization of the covariance function of the solution process to a stochastic partial differential equation is considered in the parabolic case with multiplicative Lévy noise of affine type. For the second moment of the mild solution, a well-posed deterministic space–time variational problem posed on projective and injective tensor product spaces is derived, which subsequently leads to a deterministic equation for the covariance function.
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