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| 2. |
- Benitez, Patrick L, et al.
(författare)
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Sequence-Specific Crosslinking of Electrospun, Elastin-Like Protein Preserves Bioactivity and Native-Like Mechanics.
- 2013
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Ingår i: Advanced healthcare materials. - : Wiley. - 2192-2640 .- 2192-2659. ; 2:1, s. 114-118
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Tidskriftsartikel (refereegranskat)abstract
- A nanoscale mimic of the extracellular matrix is electrospun from a highly tunable family of elastin-like proteins. A sequence-specific, two-step crosslinking procedure is developed to preserve the nanofiber morphology, elastin-like mechanics, and specific bioactivity. Rodent marrow stromal cells show sequence-specific adhesion on the matrices, which are imaged using label-free coherent anti-Stokes Raman scattering (CARS) microscopy.
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| 3. |
- Bodin, Aase Katarina, 1977, et al.
(författare)
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Influence of cultivation conditions on mechanical and morphological properties of bacterial cellulose tubes
- 2007
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 97:2, s. 425-434
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial cellulose (BC) was deposited in tubular form by fermenting Acetobacter xylinum on top of silicone tubes as an oxygenated support and by blowing different concns. of oxygen, i.e., 21% (air), 35%, 50%, and 100%. Mech. properties such as burst pressure and tensile properties were evaluated for all tubes. The burst pressure of the tubes increased with an increase in oxygen ratio and reached a top value of 880 mmHg at 100% oxygen. The Young's modulus was approx. 5 MPa for all tubes, irresp. of the oxygen ratio. The elongation to break decreased from 30% to 10-20% when the oxygen ratio was increased. The morphol. of the tubes was characterized by SEM (SEM). All tubes had an even inner side and a more porous outer side. The cross section indicated that the tubes are composed of layers and that the amt. of layers and the yield of cellulose increased with an increase in oxygen ratio. We propose that an internal vessel wall with high d. is required for the tube to sustain a certain pressure. An increase in wall thickness by an increase in oxygen ratio might explain the increasing burst pressure with increasing oxygen ratio. The fermn. method used renders it possible to produce branched tubes, tubes with unlimited length and inner diams. Endothelial cells (ECs) were grown onto the lumen of the tubes. The cells formed a confluent layer after 7 days. The tubes potential as a vascular graft is currently under investigation in a large animal model at the Center of Vascular Engineering, Sahlgrenska University Hospital, Gothenburg.
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| 4. |
- Bodin, Aase Katarina, 1977, et al.
(författare)
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Modification of nanocellulose with a xyloglucan-RGD conjugate enhances adhesion and proliferation of endothelial cells: implications for tissue engineering.
- 2007
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 8:12, s. 3697-3704
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a novel method for introducing the RGD cell adhesion peptide to enhance cell adhesion onto bacterial cellulose (BC). BC and cotton linters as reference were modified with xyloglucan (XG) and xyloglugan bearing a GRGDS pentapeptide. The adsorptions followed Langmuir adsorption behavior, where both XGs probably decorate the cellulose surfaces as a monolayer. The adsorption maximum of the XGs reached around 180 mg/g on BC and only about three times as much on cotton linters. The adsorption was verified with colorimetric methods. The specific surface area of BC measured with XG and XG-GRGDS was about 200 m (2)/g and was almost three times less for cotton linters, 60 m (2)/g. The difference in the amounts of XGs adsorbed might be explained by the swollen network of bacterial cellulose and a more exposed and accessible bulk as compared to cotton linters. The nanocellulose material was modified homogeneously throughout the material, as seen by the z-scan in confocal microscopy. Moreover, the modification in the water phase, in comparison with organic solvents, was clearly advantageous for preserving the morphology, as observed with SEM. The modification slightly increased the wettability, which might explain the decrease in or undetectable adsorption of adhesive protein shown by QCM-D. Initial cell studies showed that adhesion of human endothelial cells is enhanced when the BC hydrogel is modified with XG-GRGDS. QCM-D studies further revealed that the cell enhancement is due to the presence of the RGD epitope on XG and not to a nonspecific adsorption of fibronectin from cell culture medium. Optimization and proliferation studies of human endothelial cells onto bacterial cellulose modified with XG-GRGDS are currently being carried out at the Vascular Engineering Center, Sahlgrenska University Hospital, Gothenburg.
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| 5. |
- Cavonius, Lillie, 1981, et al.
(författare)
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Imaging lipids in live microalgae
- 2013
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Ingår i: Algae Biomass Summit 2013.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Microalgae are capable of producing lipids from CO2 and sunlight and as such the primary producers of n-3 fatty acids. Intense research is underway to understand the conditions under which optimal lipid accumulation occurs, not only for neutraceutical applications, but also for biodiesel production. To aid this research we propose the application of a powerful microscopic technique that allows monitoring of lipids with chemical specificity at intra-cellular level in living cells: Coherent anti-Stokes Raman spectroscopy (CARS). CARS is a non-linear microscopy technique that can be used to probe C-H bonds especially abundant in lipids by a process involving four-wave mixing: two or three coherent beams of different near-infra red (NIR) wavelengths are tuned to induce a resonant vibration in the C-H bonds, and generate a blue-shifted CARS signal. The NIR light used to probe the sample allows good penetration which in turn makes optical sectioning possible. By taking many optical sections of the sample, a 3D image can be constructed, from which the volume of lipids in the cell can be calculated, allowing quantitative studies of lipid accumulation in single microalgae. In our study, we used Phaeodactylum tricornutum grown under normal, light-starved and nitrogen-starved conditions. CARS microscopy detected statistically significant differences in lipid droplet number and their volumes when comparing growth conditions at single cell level. The whole population was then subjected to traditional lipid extraction and chromatographic separation of fatty acids. Average lipid volumes, as calculated from CARS microscopy, correlated well with traditional chemical analysis. As a conclusion, CARS could be applied to the in vivo study of culture condition effect on lipid accumulation in microalgae.
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| 6. |
- Cavonius, Lillie, 1981, et al.
(författare)
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Imaging lipids in live microalgae
- 2012
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Ingår i: Novel Sources of Omega-3 in Food and Feed, Copenhagen 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Microalgae are the primary producers of n-3 fatty acids in the aquatic food web, capable of producing lipids from CO2 and sunlight. Intense research is underway to understand the conditions under which optimal lipid accumulation occurs. To aid this research we propose the application of a powerful microscopic technique that allows monitoring of lipids with chemical specificity at intra-cellular level in living cells. While fluorescence microscopy with an appropriate dye can be highly specific, cells must be fixed and permeabilized, excluding live-cell studies; other techniques, such as phase contrast microscopy can be applied to living cells, but they lack chemical specificity. Coherent anti-Stokes Raman spectroscopy (CARS) is a non-linear microscopy technique that probes C-H bonds especially abundant in lipids by a process involving four-wave mixing: two or three coherent beams of different near-infra red (NIR) wavelengths are tuned to induce a resonant vibration in the C-H bonds, and generate a blue-shifted CARS signal in the visible region. Multi-photon autofluorescence from e.g. pigments in the sample can be detected simultaneously. The NIR light used to illuminate the sample allows good penetration which in turn makes optical sectioning possible. By taking many optical sections of the sample a 3D image can be constructed, from which the volume of lipids in the cell can be calculated, allowing quantitative studies of lipid accumulation in single microalgae. We herein present a proof-of-concept in the comparison of Phaeodactylum tricornutum grown under normal light-starved and nitrogen-starved conditions.
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| 7. |
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| 8. |
- Cavonius, Lillie, 1981, et al.
(författare)
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Imaging of Lipids in Microalgae with Coherent Anti-Stokes Raman Scattering Microscopy
- 2015
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 1532-2548 .- 0032-0889. ; 167:3, s. 603-616
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Tidskriftsartikel (refereegranskat)abstract
- Microalgae have great prospects as a sustainable resource of lipids for refinement into nutraceuticals and biodiesel, which increases the need for detailed insights into their intracellular lipid synthesis/storage mechanisms. As an alternative strategy to solvent- and label-based lipid quantification techniques, we introduce time-gated coherent anti-Stokes Raman scattering (CARS) microscopy for monitoring lipid contents in living algae, despite strong autofluorescence from the chloroplasts, at approximately picogram and subcellular levels by probing inherent molecular vibrations. Intracellular lipid droplet synthesis was followed in Phaeodactylum tricornutum algae grown under (1) light/nutrient-replete (control [Ctrl]), (2) light-limited (LL), and (3) nitrogen-starved (NS) conditions. Good correlation (r2 = 0.924) was found between lipid volume data yielded by CARS microscopy and total fatty acid content obtained from gas chromatography-mass spectrometry analysis. In Ctrl and LL cells, micron-sized lipid droplets were found to increase in number throughout the growth phases, particularly in the stationary phase. During more excessive lipid accumulation, as observed in NS cells, promising commercial harvest as biofuels and nutritional lipids, several micron-sized droplets were present already initially during cultivation, which then fused into a single giant droplet toward stationary phase alongside with new droplets emerging. CARS microspectroscopy further indicated lower lipid fluidity in NS cells than in Ctrl and LL cells, potentially due to higher fatty acid saturation. This agreed with the fatty acid profiles gathered by gas chromatography-mass spectrometry. CARS microscopy could thus provide quantitative and semiqualitative data at the single-cell level along with important insights into lipid-accumulating mechanisms, here revealing two different modes for normal and excessive lipid accumulation.
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| 9. |
- Enejder, Annika, 1969, et al.
(författare)
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CARS microscopy of Alzheimer's diseased brain tissue
- 2014
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 8948
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Konferensbidrag (refereegranskat)abstract
- Alzheimera's disease (AD) is a progressive neurodegenerative disorder currently without cure, characterized by the presence of extracellular plaques surrounded by dystrophic neurites. In an effort to understand the underlying mechanisms, biochemical analysis (protein immunoblot) of plaque extracts reveals that they consist of amyloid-beta (Aβ) peptides assembled as oligomers, protofibrils and aggregates. Their spatial distribution has been confirmed by Thioflavin-S or immuno-staining with fluorescence microscopy. However, it is increasingly understood that the protein aggregation is only one of several mechanism that causes neuronal dysfunction and death. This raises the need for a more complete biochemical analysis. In this study, we have complemented 2-photon fluorescence microscopy of Thioflavin-S and Aβ immuno-stained human AD plaques with CARS microscopy. We show that the chemical build-up of AD plaques is more complex and that Aβ staining does not provide the complete picture of the spatial distribution or the molecular composition of AD plaques. CARS images provide important complementary information to that obtained by fluorescence microscopy, motivating a broader introduction of CARS microscopy in the AD research field.
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| 10. |
- Enejder, Annika, 1969, et al.
(författare)
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Neuronal cell growth on polymeric scaffolds studied by CARS microscopy
- 2012
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Ingår i: Proceedings of SPIE - Multiphoton Microscopy in the Biomedical Sciences XII, San Francisco, CA, 22-24 January 2012. - : SPIE. - 1605-7422. - 9780819488695 ; 8226
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Konferensbidrag (refereegranskat)abstract
- For studies of neuronal cell integration and neurite outgrowth in polymeric scaffold materials as a future alternative for the treatment of damages in the neuronal system, we have developed a protocol employing CARS microscopy for imaging of neuronal networks. The benefits of CARS microscopy come here to their best use; (i) the overall three-dimensional (3D) arrangement of multiple cells and their neurites can be visualized without the need for chemical preparations or physical sectioning, potentially affecting the architecture of the soft, fragile scaffolds and (ii) details on the interaction between single cells and scaffold fibrils can be investigated by close-up images at sub-micron resolution. The establishment of biologically more relevant 3D neuronal networks in a soft hydrogel composed of native Extra Cellular Matrix (ECM) components was compared with conventional two-dimensional networks grown on a stiff substrate. Images of cells in the hydrogel scaffold reveal significantly different networking characteristics compared to the 2D networks, raising the question whether the functionality of neurons grown as layers in conventional cultivation dishes represents that of neurons in the central and peripheral nervous systems.
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