| 1. |
- Apelgren, Peter, et al.
(författare)
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Biomaterial and biocompatibility evaluation of tunicate nanocellulose for tissue engineering.
- 2022
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Ingår i: Biomaterials advances. - : Elsevier BV. - 2772-9508. ; 137
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Tidskriftsartikel (refereegranskat)abstract
- Extracellular matrix fibril components, such as collagen, are crucial for the structural properties of several tissues and organs. Tunicate-derived cellulose nanofibrils (TNC) combined with living cells could become the next gold standard for cartilage and soft-tissue repair, as TNC fibrils present similar dimensions to collagen, feasible industrial production, and chemically straightforward and cost-efficient extraction procedures. In this study, we characterized the physical properties of TNC derived from aquaculture production in Norwegian fjords and evaluated its biocompatibility regarding induction of an inflammatory response and foreign-body reactions in a Wistar rat model. Additionally, histologic and immunohistochemical analyses were performed for comparison with expanded polytetrafluoroethylene (ePTFE) as a control. The average length of the TNC as determined by atomic force microscopy was tunable from 3μm to 2.4μm via selection of a various number of passages through a microfluidizer, and rheologic analysis showed that the TNC hydrogels were highly shear-thinning and with a viscosity dependent on fibril length and concentration. As a bioink, TNC exhibited excellent rheological and printability properties, with constructs capable of being printed with high resolution and fidelity. We found that post-print cross-linking with alginate stabilized the construct shape and texture, which increased its ease of handling during surgery. Moreover, after 30days in vivo, the constructs showed a highly-preserved shape and fidelity of the grid holes, with these characteristics preserved after 90days and with no signs of necrosis, infection, acute inflammation, invasion of neutrophil granulocytes, or extensive fibrosis. Furthermore, we observed a moderate foreign-body reaction involving macrophages, lymphocytes, and giant cells in both the TNC constructs and PTFE controls, although TNC was considered a non-irritant biomaterial according to ISO 10993-6 as compared with ePTFE. These findings represent a milestone for future clinical application of TNC scaffolds for tissue repair. One sentence summary: In this study, the mechanical properties of tunicate nanocellulose are superior to nanocellulose extracted from other sources, and the biocompatibility is comparable to that of ePTFE.
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| 2. |
- Dahlgren, Kristin, et al.
(författare)
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Seasonal variation in wax ester concentration and gut content in a Baltic Sea copepod [Limnocalanus macrurus (Sars 1863)]
- 2012
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Ingår i: Journal of Plankton Research. - Oxford : Oxford University Press. - 0142-7873 .- 1464-3774. ; 34:4, s. 286-297
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Tidskriftsartikel (refereegranskat)abstract
- Limnocalanus macrurus from Bothnian Bay in the northern part of the Baltic Sea was studied during the ice-free period (AprilDecember) in order to understand its life history and feeding biology. Our data on the population dynamics indicated that reproduction occurred during the ice-covered period, during which lipid storage was reduced to a minimum. From spring to late summer, the lipid reserve increased by a factor of 3, while the gonads of adult females were immature during this period, continuing to December as indicated by the small size of the eggs. Average stomach fullness was always ca. 50 indicating continuous feeding activity. A newly developed denaturing high-performance liquid chromatography method was used to analyse the gut contents over the study period. More than 30 taxa (at different taxonomic levels) could be identified. However, phytoplankton was only represented by one taxon (Diatomophycea), and was restricted to July. Thus, adult L. macrurus seems to have a strongly carnivorous feeding preference in the northern Baltic Sea.
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| 3. |
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| 4. |
- Kjesbu, Joachim S., et al.
(författare)
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Alginate and tunicate nanocellulose composite microbeads – Preparation, characterization and cell encapsulation
- 2022
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 286
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Tidskriftsartikel (refereegranskat)abstract
- Alginate has been used for decades for cell encapsulation. Cellulose nanofibrils (CNF) from tunicates are desirable in biomedicine due to high molecular weight, purity, crystallinity, and sustainable production. We prepared microbeads of 400–600 μm of alginate and tunicate CNF. Greater size, dispersity and aspect ratio were observed in microbeads with higher fractions of CNF. CNF content in Ca-crosslinked alginate microbeads decreased stability upon saline exposure, whereas crosslinking with calcium (50 mM) and barium (1 mM) yielded stable microbeads. The Young's moduli of gel cylinders decreased when exchanging alginate with CNF, and slightly increased permeability to dextran was observed in microbeads containing CNF. Encapsulation of MC3T3 cells revealed high cell viability after encapsulation (83.6 ± 0.4%) in beads of alginate and CNF. NHDFs showed lower viability but optimizing mixing and production techniques of microbeads increased cell viability (from 66.2 ± 5.3% to 72.7 ± 7.5%).
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| 5. |
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| 6. |
- Olsen, Bernt Rydland, et al.
(författare)
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PCR-DHPLC assay for the identification of predator-prey interactions
- 2012
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Ingår i: Journal of Plankton Research. - Oxford : Oxford University Press. - 0142-7873 .- 1464-3774. ; 34:4, s. 277-285
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Tidskriftsartikel (refereegranskat)abstract
- Denaturing high-performance liquid chromatography (DHPLC) is a relatively new method for separating amplicons in a mixture, and was recently developed for parasite detection in the blue crab Callinectes sapidus. That assay used a peptide nucleic acid (PNA) PCR hybridization blocking probe (PNAPCRDHPLC) to decrease the generic PCR bias of dominant templates (the host) in the mixture prior to separation on the DHPLC column, thus enhancing the less abundant parasite DNA. The same assay and rational can be used to investigate predatorprey interactions. However, in ecosystem studies with many predatorprey relationships, development of specific PNA-blocking probes for each predator would be too laborious. Here, we have developed a PCRDHPLC assay excluding the dominant predator amplicons in a first DHPLC run, followed by re-amplification of the non-predator retention volumes and further separation and characterization in a second DHPLC run. This assay generated data on the specific trophic interactions between the calanoid copepod Limnocalanus macrurus and its prey from a seasonal sampling programme. The assay provides an efficient way for an unbiased screening of predatorprey relationships, and although developed for L. macrurus in this study, the approach has wide applicability for any predatorprey interaction.
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| 7. |
- Oskarsdotter, Kristin, 1995, et al.
(författare)
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Injectable In Situ Crosslinking Hydrogel for Autologous Fat Grafting
- 2023
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Ingår i: Gels. - 2310-2861. ; 9:10
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Tidskriftsartikel (refereegranskat)abstract
- Autologous fat grafting is hampered by unpredictable outcomes due to high tissue resorption. Hydrogels based on enzymatically pretreated tunicate nanocellulose (ETC) and alginate (ALG) are biocompatible, safe, and present physiochemical properties capable of promoting cell survival. Here, we compared in situ and ex situ crosslinking of ETC/ALG hydrogels combined with lipoaspirate human adipose tissue (LAT) to generate an injectable formulation capable of retaining dimensional stability in vivo. We performed in situ crosslinking using two different approaches; inducing Ca2+ release from CaCO3 microparticles (CMPs) and physiologically available Ca2+ in vivo. Additionally, we generated ex situ-crosslinked, 3D-bioprinted hydrogel-fat grafts. We found that in vitro optimization generated a CMP-crosslinking system with comparable stiffness to ex situ-crosslinked gels. Comparison of outcomes following in vivo injection of each respective crosslinked hydrogel revealed that after 30 days, in situ crosslinking generated fat grafts with less shape retention than 3D-bioprinted constructs that had undergone ex situ crosslinking. However, CMP addition improved fat-cell distribution and cell survival relative to grafts dependent on physiological Ca2+ alone. These findings suggested that in situ crosslinking using CMP might promote the dimensional stability of injectable fat-hydrogel grafts, although 3D bioprinting with ex situ crosslinking more effectively ensured proper shape stability in vivo.
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| 8. |
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| 9. |
- Troedsson, Christofer, et al.
(författare)
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Effects of ocean acidification, temperature and nutrient regimes on the appendicularian Oikopleura dioica: A mesocosm study
- 2013
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Ingår i: Marine Biology. - 0025-3162. ; 160:8, s. 2175-2187
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Tidskriftsartikel (refereegranskat)abstract
- ncreasing pCO2 is hypothesized to induce shifts in plankton communities toward smaller cells, reduced carbon export rates and increased roles of gelatinous zooplankton. Appendicularians, among the most numerous pan-global “gelatinous” zooplankton, continuously produce filter-feeding houses, shortcutting marine food webs by ingesting submicron particles, and their discarded houses contribute significantly to carbon fluxes. We present a first mesocosm-scale study on the effects of temperature, pCO2 and bloom structures on the appendicularian, Oikopleura dioica. There were effects of temperature and nutrients on phytoplankton communities. No shifts in functional phytoplankton groups, nor changes in particle sizes/morphotypes, known to impact appendicularian feeding, were observed under manipulated pCO2 conditions. However, appendicularian abundance was positively correlated with increased pCO2, temperature and nutrient levels, consistent with hypotheses concerning gelatinous zooplankton in future oceans. This suggests appendicularians will play more important roles in marine pelagic communities and vertical carbon transport under projected ocean acidification and elevated temperature scenarios.
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| 10. |
- Winder, Monika, et al.
(författare)
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Increased appendicularian zooplankton alter carbon cycling under warmer more acidified ocean conditions
- 2017
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Ingår i: Limnology and Oceanography. - : John Wiley & Sons. - 0024-3590 .- 1939-5590. ; 62:4, s. 1541-1551
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic atmospheric loading of CO2 raises concerns about combined effects of increasing ocean temperature and acidification, on biological processes. In particular, the response of appendicularian zooplankton to climate change may have significant ecosystem implications as they can alter biogeochemical cycling compared to classical copepod dominated food webs. However, the response of appendicularians to multiple climate drivers and effect on carbon cycling are still not well understood. Here, we investigated how gelatinous zooplankton (appendicularians) affect carbon cycling of marine food webs under conditions predicted by future climate scenarios. Appendicularians performed well in warmer conditions and benefited from low pH levels, which in turn altered the direction of carbon flow. Increased appendicularians removed particles from the water column that might otherwise nourish copepods by increasing carbon transport to depth from continuous discarding of filtration houses and fecal pellets. This helps to remove CO2 from the atmosphere, and may also have fisheries implications.
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| 11. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Mechanically Reinforced, Flexible, Hydrophobic and UV Impermeable Starch-Cellulose Nanofibers (CNF)-Lignin Composites with Good Barrier and Thermal Properties
- 2021
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 13:24, s. 4346-
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Tidskriftsartikel (refereegranskat)abstract
- Bio-based composite films have been widely studied as potential substitutes for conventional plastics in food packaging. The aim of this study was to develop multifunctional composite films by introducing cellulose nanofibers (CNF) and lignin into starch-based films. Instead of costly and complicated chemical modification or covalent coupling, this study optimized the performance of the composite films by simply tuning the formulation. We found that starch films were mechanically reinforced by CNF, with lignin dispersing as nanoparticles embedded in the matrix. The newly built-up hydrogen bonding between these three components improves the integration of the films, while the introduction of CNF and lignin improved the thermal stability of the starch-based films. Lignin, as a functional additive, improved hydrophobicity and blocked UV transmission. The inherent barrier property of CNF and the dense starch matrix provided the composite films with good gas barrier properties. The prepared flexible films were optically transparent, and exhibited UV blocking ability, good oxygen-barrier properties, high hydrophobicity, appreciable mechanical strength and good thermal stability. These characteristics indicate potential utilization as a green alternative to synthetic plastics especially for food packaging applications.
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