| 1. |
- Abadpour, Shadab, et al.
(författare)
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Adipose-Derived Stromal Cells Preserve Pancreatic Islet Function in a Transplantable 3D Bioprinted Scaffold
- 2023
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Ingår i: Advanced healthcare materials. - 2192-2640 .- 2192-2659. ; 12:32
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Tidskriftsartikel (refereegranskat)abstract
- Intra-portal islet transplantation is currently the only clinically approved beta cell replacement therapy, but its outcome is hindered by limited cell survival due to a multifactorial reaction against the allogeneic tissue in liver. Adipose-derived stromal cells (ASCs) can potentially improve the islet micro-environment by their immunomodulatory action. The challenge is to combine both islets and ASCs in a relatively easy and consistent long-term manner in a deliverable scaffold. Manufacturing the 3D bioprinted double-layered scaffolds with primary islets and ASCs using a mix of alginate/nanofibrillated cellulose (NFC) bioink is reported. The diffusion properties of the bioink and the supportive effect of human ASCs on islet viability, glucose sensing, insulin secretion, and reducing the secretion of pro-inflammatory cytokines are demonstrated. Diabetic mice transplanted with islet-ASC scaffolds reach normoglycemia seven days post-transplantation with no significant difference between this group and the group received islets under the kidney capsules. In addition, animals transplanted with islet-ASC scaffolds stay normoglycemic and show elevated levels of C-peptide compared to mice transplanted with islet-only scaffolds. The data present a functional 3D bioprinted scaffold for islets and ASCs transplanted to the extrahepatic site and suggest a possible role of ASCs on improving the islet micro-environment.
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| 2. |
- Kallas, Pawel, et al.
(författare)
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Adhesion of Escherichia Coli to Nanostructured Surfaces and the Role of Type 1 Fimbriae
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial fimbriae are an important virulence factor mediating adhesion to both biotic and abiotic surfaces and facilitating biofilm formation. The expression of type 1 fimbriae of Escherichia coli is a key virulence factor for urinary tract infections and catheter-associated urinary tract infections, which represent the most common nosocomial infections. New strategies to reduce adhesion of bacteria to surfaces is therefore warranted. The aim of the present study was to investigate how surfaces with different nanotopography-influenced fimbriae-mediated adhesion. Surfaces with three different nanopattern surface coverages made in polycarbonate were fabricated by injection molding from electron beam lithography nanopatterned templates. The surfaces were constructed with features of approximately 40 nm width and 25 nm height with 100 nm, 250 nm, and 500 nm interspace distance, respectively. The role of fimbriae type 1-mediated adhesion was investigated using the E. coli wild type BW25113 and Delta fimA (with a knockout of major pilus protein FimA) and Delta fimH (with a knockout of minor protein FimH) mutants. For the surfaces with nanotopography, all strains adhered least to areas with the largest interpillar distance (500 nm). For the E. coli wild type, no difference in adhesion between surfaces without pillars and the largest interpillar distance was observed. For the deletion mutants, increased adhesion was observed for surfaces without pillars compared to surfaces with the largest interpillar distance. The presence of a fully functional type 1 fimbria decreased the bacterial adhesion to the nanopatterned surfaces in comparison to the mutants.
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| 3. |
- Kallas, Pawel, et al.
(författare)
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Protein-coated nanostructured surfaces affect the adhesion of Escherichia coli
- 2022
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 14:20, s. 7736-7746
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Tidskriftsartikel (refereegranskat)abstract
- Developing new implant surfaces with anti-adhesion bacterial properties used for medical devices remains a challenge. Here we describe a novel study investigating nanotopography influences on bacterial adhesion on surfaces with controlled interspatial nanopillar distances. The surfaces were coated with proteins (fibrinogen, collagen, serum and saliva) prior to E. coli-WT adhesion under flow conditions. PiFM provided chemical mapping and showed that proteins adsorbed both between and onto the nanopillars with a preference for areas between the nanopillars. E. coli-WT adhered least to protein-coated areas with low surface nanopillar coverage, most to surfaces coated with saliva, while human serum led to the lowest adhesion. Protein-coated nanostructured surfaces affected the adhesion of E. coli-WT.
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| 4. |
- Wiedmer, David, et al.
(författare)
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Oxidative power of aqueous non-irradiated TiO2-H2O2 suspensions : Methylene blue degradation and the role of reactive oxygen species
- 2016
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 198, s. 9-15
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the degradation of methylene blue in non-irradiated TiO2-H2O2 suspensions was investigated. Five commercially available catalysts were characterized (BET surface area, zeta potential, hydrodynamic diameter) and their oxidative power was assessed by means of the degradation of methylene blue. A subsequent EPR study was made to verify and identify potential oxidative radicals. The results showed that all suspensions could degrade methylene blue significantly stronger compared to hydrogen peroxide alone. A broad variation between the different catalysts in their capability to adsorb dye molecules was found which was essential for decomposition of methylene blue in darkness. The highest degradation rate of all samples was found for Degussa P25 at neutral pH. EPR studies of this sample verified the presence of oxygen centred radicals namely hydroxyl ((OH)-O-center dot) and superoxide radicals (O-2(-center dot)/(OOH)-O-center dot). Non-irradiated TiO2-H2O2 systems show great potential not only in dye removal applications but also in the field of disinfection where low concentrations of hydrogen peroxide are required and irradiation may not be feasible.
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