| 1. |
- Bengtsson, Anton, 1979, et al.
(författare)
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Effects of thermal processing on the in vitro bioaccessibility and microstructure of beta-carotene in orange-fleshed sweet potato
- 2010
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 58:20, s. 11090-11096
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different preparation methods on the bioaccessibility of beta-carotene in orange-fleshed sweet potato (OFSP), an important food crop in sub-Saharan Africa, have been evaluated using an in vitro digestion procedure. The preparation methods included, on fresh roots, boiling followed by pureeing and oil addition (BOL) and homogenization followed by boiling and oil addition (HOM); on milled flour from freeze-dried fresh roots, cooking of porridge followed by oil addition (POA) and oil addition to flour followed by cooking of porridge (POB). The retention of all-trans-beta-carotene ranged from 58% (POB) to 72% (BOL). The presence of oil during heating resulted in a significantly higher formation of 13-cis-beta-carotene for the POB-treated samples than for the other samples. The efficiency of micellarization of all-trans-beta-carotene after in vitro digestion was 50% (HOM), 48% (POB), 31% (POA), and 16% (BOL). Brightfield microscopy of the cell structure after processing and in vitro digestion showed a high degree of cell-wall rupture for the HOM-treated samples, whereas cells appeared intact for the BOL samples. Also, coherent anti-Stokes Raman scattering (CARS) microscopy showed smaller beta-carotene bodies residing in the HOM samples than in the BOL samples after digestion. These results suggest that the in vitro bioaccessibility of beta-carotene in an OFSP meal can be improved by processing methods that promote cell-wall rupture.
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| 2. |
- Brackmann, Christian, et al.
(författare)
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Characterization of ammonia two-photon laser-induced fluorescence for gas-phase diagnostics
- 2014
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 115:1, s. 25-33
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon laser-induced fluorescence (LIF) of ammonia (NH3) with excitation of the C'-X transition at 304.8 nm and fluorescence detection in the 565 nm C'-A band has been investigated, targeting combustion diagnostics. The impact of laser irradiance, temperature, and pressure has been studied, and simulation of NH3-spectra, fitted to experimental data, facilitated interpretation of the results. The LIF-signal showed quadratic dependence on laser irradiance up to 2 GW/cm(2). Stimulated emission, resulting in loss of excited molecules, is induced above 10 GW/cm(2), i.e., above irradiances attainable for LIF imaging. Maximum LIF-signal was obtained for excitation at the 304.8 nm bandhead; however, lower temperature sensitivity over the range 400-700 K can be obtained probing lines around 304.9 nm. A decrease in fluorescence signal was observed with pressure up to 5 bar absolute and attributed to collisional quenching. A detection limit of 800 ppm, at signal-to-noise ratio 1.5, was identified for single-shot LIF imaging over an area of centimeter scale, whereas for single-point measurements, the technique shows potential for sub-ppm detection. Moreover, high-quality NH3-imaging has been achieved in laminar and turbulent premixed flames. Altogether, two-photon fluorescence provides a useful tool for imaging NH3-detection in combustion diagnostics.
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| 3. |
- Brackmann, Christian, 1973, et al.
(författare)
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Coherent anti-Stokes Raman scattering microscopy of human smooth muscle cells in bioengineered tissue scaffolds
- 2011
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Ingår i: Journal of Biomedical Optics. - : SPIE - International Society for Optical Engineering. - 1083-3668 .- 1560-2281. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- The integration of living, human smooth muscle cells in biosynthesized cellulose scaffolds was monitored by nonlinear microscopy toward contractile artificial blood vessels. Combined coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) microscopy was applied for studies of the cell interaction with the biopolymer network. CARS microscopy probing CH(2)-groups at 2845 cm(-1) permitted three-dimensional imaging of the cells with high contrast for lipid-rich intracellular structures. SHG microscopy visualized the fibers of the cellulose scaffold, together with a small signal obtained from the cytoplasmic myosin of the muscle cells. From the overlay images we conclude a close interaction between cells and cellulose fibers. We followed the cell migration into the three-dimensional structure, illustrating that while the cells submerge into the scaffold they extrude filopodia on top of the surface. A comparison between compact and porous scaffolds reveals a migration depth of <10 μm for the former, whereas the porous type shows cells further submerged into the cellulose. Thus, the scaffold architecture determines the degree of cell integration. We conclude that the unique ability of nonlinear microscopy to visualize the three-dimensional composition of living, soft matter makes it an ideal instrument within tissue engineering.
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| 4. |
- Brackmann, Christian, 1973, et al.
(författare)
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In situ Imaging of Collagen Synthesis by Osteoprogenitor Cells in Microporous Bacterial Cellulose Scaffolds.
- 2012
-
Ingår i: Tissue Engineering - Part C: Methods. - 1937-3384 .- 1937-3392. ; 18:3, s. 227-234
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Tidskriftsartikel (refereegranskat)abstract
- Microscopy techniques based on laser-induced nonlinear optical processes allow for chemically specific imaging of unmodified samples at high spatial resolution in three dimensions and provide powerful tools for characterization of tissue-engineering constructs. This is highlighted by the simultaneous imaging of scaffold material, cells, and produced extracellular matrix collagen in samples consisting of osteoprogenitor MC3T3-E1 cells seeded on microporous bacterial cellulose (BC), a potential scaffold material for synthesis of osseous tissue. BC and collagen have been visualized by second harmonic generation (SHG) microscopy, and verification of collagen identification on cellulose scaffolds has been carried out on sectioned samples by comparison with the conventional histological staining technique. Both methods showed similar collagen distributions and a clear increase in the amount of collagen when comparing measurements from two time points during growth. For investigations of intact cellulose scaffolds seeded with cells, SHG was combined with simultaneous coherent anti-Stokes Raman scattering (CARS) microscopy for visualization of cell arrangement in three dimensions and to be correlated with the SHG data. Results showed that the osteoprogenitor cells were able to produce collagen already during the first days of growth. Further on, developed collagen fiber networks could be imaged inside compact regions of cells located in the cellulose micropores. Collagen production, the initial step of tissue mineralization, demonstrates the potential of BC as a scaffold material for bone tissue engineering. Furthermore, the noninvasive in situ monitoring of collagen inside compact tissue clearly manifests the benefits of nonlinear microscopy techniques, such as SHG and CARS, for use in tissue engineering.
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| 5. |
- Brackmann, Christian, 1973, et al.
(författare)
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Non-linear microscopy of smooth muscle cells in artificial extracellular matrices made of cellulose
- 2012
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 5:5-6, s. 404-414
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Tidskriftsartikel (refereegranskat)abstract
- Non-linear microscopy has been used to characterize bovine smooth muscle cells and their proliferation, migration, and differentiation in hydrogel cellulose scaffolds, toward the development of fully functional blood vessel implants. The extracellular matrix (ECM) composed of cellulose and endogenous collagen fibers was imaged using Second Harmonic Generation (SHG) microscopy and the cell morphology by Coherent Anti-Stokes Raman Scattering (CARS) microscopy. Images prove that cells adhere on the cellulose scaffold without additional surface modification and that both contractile and proliferating phenotypes are developed. This work shows that non-linear microscopy contributes with unique insights in cell interactions with (artificial) ECM components and has the potential to become an established characterization method in tissue engineering.
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| 6. |
- Brackmann, Christian, 1973, et al.
(författare)
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Nonlinear microscopy of lipid storage and fibrosis in muscle and liver tissues of mice fed high-fat diets
- 2010
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 15:6
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Tidskriftsartikel (refereegranskat)abstract
- Hallmarks of high-fat Western diet intake, such as excessive lipid accumulation in skeletal muscle and liver as well as liver fibrosis, are investigated in tissues from mice using nonlinear microscopy, second harmonic generation (SHG), and coherent anti-Stokes Raman scattering (CARS), supported by conventional analysis methods. Two aspects are presented; intake of standard chow versus Western diet, and a comparison between two high-fat Western diets of different polyunsaturated lipid content. CARS microscopy images of intramyocellular lipid droplets in muscle tissue show an increased amount for Western diet compared to standard diet samples. Even stronger diet impact is found for liver samples, where combined CARS and SHG microscopy visualize clear differences in lipid content and collagen fiber development, the latter indicating nonalcoholic fatty liver disease (NAFLD) and steatohepatitis induced at a relatively early stage for Western diet. Characteristic for NAFLD, the fibrous tissue-containing lipids accumulate in larger structures. This is also observed in CARS images of liver samples from two Western-type diets of different polyunsaturated lipid contents. In summary, nonlinear microscopy has strong potential (further promoted by technical advances toward clinical use) for detection and characterization of steatohepatitis already in its early stages.
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| 7. |
- Brackmann, Christian, et al.
(författare)
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Picosecond excitation for reduction of photolytic effects in two-photon laser-induced fluorescence of CO
- 2013
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 34, s. 3541-3548
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon laser-induced fluorescence for detection of carbon monoxide (CO) frequently shows interferences by emission from photolytically produced C-2 radicals encountered under fuel-rich combustion conditions. Reduced C-2 interference for excitation with laser pulses in the picosecond regime is here demonstrated by comparison with excitation using nanosecond pulses for measurements in laminar premixed ethene-air flames. Compared with nanosecond pulses of 8 ns duration and 4 mJ pulse energy, picosecond pulses of 80 ps duration and around 0.5 mJ pulse energy gave similar to 10 times higher peak power, which allowed for efficient CO excitation and resulted in stronger signal with lower C-2 interference. CO fluorescence with picosecond excitation showed a linear to quadratic power dependence, indicating photoionization, whereas a more quadratic dependence was found for the C-2 interference. A sub-nanosecond effective lifetime of CO resulted in a rapid fluorescence decay compared with C-2 and allowed for efficient reduction in C-2 interference by minimizing the detection gate. In addition, interference compensation using time-resolved detection could be demonstrated. Altogether, picosecond pulses provide efficient two-photon excitation of CO in terms of signal strength as well as reduced C-2 interference. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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| 8. |
- Brackmann, Christian, 1973, et al.
(författare)
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Visualization of the Cellulose Biosynthesis and Cell Integration into Cellulose Scaffolds
- 2010
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 11:3, s. 542-548
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Tidskriftsartikel (refereegranskat)abstract
- By controlling the microarchitecture of bioengineered scaffolds for artificial tissues, their material and cell-interaction properties can be designed to mimic native correspondents. Current understanding of this relationship is sparse and based oil microscopy requiring harsh sample preparation and labeling, leaving it open to which extent the natural morphology is studied. This work introduces multimodal nonlinear microscopy for label-free imaging of tissue scaffolds, exemplified by bacterial Cellulose. Unique three-dimensional images visualizing the formation of nanofiber networks throughout the biosynthesis, revealing that supra-structures (layered structures, cavities) are formed. Cell integration in compact scaffolds was visualized and compared with porous scaffolds. While the former showed distinct boundaries to the native tissue, gradual Cell integration was observed for the porous material. Thus, the degree of cell integration can be controlled through scaffold supra-structures. This illustrates the potential of nonlinear microscopy for noninvasive imaging of the intriguing interaction mechanisms between scaffolds and cells.
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| 9. |
- Brackmann, Christian, 1973, et al.
(författare)
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Visualization of β-carotene and starch granules in plant cells using CARS and SHG microscopy
- 2010
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 42:4, s. 586-592
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Tidskriftsartikel (refereegranskat)abstract
- Information on the content and bioavailability of provitamin A carotenoids, such as beta-carotene, in plant foods is of great interest due to the widespread vitamin A deficiency in developing countries. While the amount of beta-carotene can readily be quantified with analytical techniques, there is limited information on beta-carotene morphology in native plant materials. Here, we introduce nonlinear microscopy for three-dimensional, label-free imaging of carotenoids in fresh and thermally treated plant tissues, providing quantitative information at single-aggregate level and detailed insight into their distribution. Carotenoids in orange-fleshed sweet potato (OFSP), carrot, and mango were visualized by coherent anti-Stokes Raman scattering (CARS) microscopy and, in the case of OFSP, related to the plant-matrix morphology by simultaneous second-harmonic generation (SHG) microscopy of starch granules. Sizes, shapes, densities, and location of different types of carotenoid bodies were quantified. While OFSP and carrot showed heterogeneous rod-shaped bodies with high carotenoid densities indicated by higher CARS signals, the carotenoid-filled lipid droplets in mango appeared as homogeneous low-density aggregates of rounded shape. In addition, beta-carotene densities and morphologies in OFSP were studied after thermal processing, showing that the bodies remain intact despite significant changes of the surrounding starch granules.
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| 10. |
- Chumnanpuen, Pramote, 1983, et al.
(författare)
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Lipid biosynthesis monitored at the single-cell level in Saccharomyces cerevisiae
- 2012
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Ingår i: Biotechnology journal. - : Wiley. - 1860-6768 .- 1860-7314. ; 7:5, s. 594-601
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Tidskriftsartikel (refereegranskat)abstract
- There is increasing interest in bioengineering of lipids for use in functional foods, pharmaceuticals, and biofuels. Saccharomyces cerevisiae is a widely utilized cell factory for biotechnological production, thus a tempting alternative. Herein, we show how its neutral lipid accumulation varies throughout metabolic phases under nutritional conditions relevant for large-scale fermentation. Population-averaged metabolic data were correlated with lipid storage at the single-cell level monitored at submicron resolution by label-free coherent anti-Stokes Raman scattering (CARS) microscopy. While lipid droplet sizes are fairly constant, the number of droplets is a dynamic parameter determined by glucose and ethanol levels. The lowest number of lipid droplets is observed in the transition phase between glucose and ethanol fermentation. It is followed by a buildup during the ethanol phase. The surplus of accumulated lipids is then mobilized at concurrent glucose and ethanol starvation in the subsequent stationary phase. Thus, the highest amount of lipids is found in the ethanol phase, which is about 0.3 fL/cell. Our results indicate that the budding yeast, S. cerevisiae, can be used for the biosynthesis of lipids and demonstrate the strength of CARS microscopy for monitoring the dynamics of lipid metabolism at the single-cell level of importance for optimized lipid production.
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| 11. |
- Enejder, Annika, 1969, et al.
(författare)
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CARS and SHG microscopy of artificial bioengineered tissues
- 2010
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819479655 ; 7569
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Major efforts are presently made to develop artificial replacement tissues with optimal architectural and material characteristics, mimicking those of their natural correspondents. Encouraged by the readiness with which cellulose fibers woven by the bacteria Acetobacter xylinum can be formed into organ-like macroscopic shapes and with different microscopic textures, it emerges as an interesting material within tissue engineering. We have developed a protocol employing simultaneous CARS and SHG microscopy for monitoring the cellulose network characteristics and its impact on the integration of smooth muscle cells (SMCs) for functionalized artificial tissues. CARS and SHG overlay images of the cells and the cellulose fibers reveal an immediate interaction irrespective of scaffold morphology and that the SMCs attach to the cellulose fibers already during the first cultivation day without cell-adhesive coatings. During the subsequent 28 days, SMCs were found to readily proliferate and differentiate on the cellulose scaffold without the need for exogenous growth factors. However, the efficiency with which this occurred depended on the topography of the cellulose constructs, benefited by porous and less compact matrices. This brings forward the need for in-depth studies on how the microstructure of tissue scaffolds influences and can be optimized for native cell integration and proliferation, studies where the benefits of multi-modal non-linear microscopy can be fully exploited. © 2010 Copyright SPIE - The International Society for Optical Engineering.
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| 12. |
- Enejder, Annika, 1969, et al.
(författare)
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Coherent Anti-Stokes Raman Scattering Microscopy
- 2012
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Ingår i: Biomedical Imaging: Principles and Applications. - : Wiley. - 9780470648476 ; , s. 304-330
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Enejder, Annika, 1969, et al.
(författare)
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Coherent Anti-Stokes Raman Scattering Microscopy of Cellular Lipid Storage
- 2010
-
Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1558-4542 .- 1077-260X. ; 16:3, s. 506-515
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Tidskriftsartikel (refereegranskat)abstract
- With the increasing number of studies using nonlinear microscopy in the biosciences, an awareness for the potentials of nonlinear optics has begun to emerge among a broader audience. Coherent anti-Stokes Raman scattering (CARS) microscopy is one of the most technically challenging methods in this category, forming images of molecular distributions based on their vibrations by a multiphoton interaction process. The primary strength of CARS microscopy lies in the ability of imaging lipids; the full 3-D distribution in living cells can be mapped without exogenous tags. Thus, CARS microscopy has a strong potential to become a central instrument for in vivo studies of the lipid metabolism at cellular level, improving present understanding of the mechanisms behind the many metabolism-related diseases, the impact of natural bioactive components in foods, and supporting the development of efficient pharmaceuticals as well as bioengineering processes exploiting the metabolism of microorganisms for the production of alternative energy sources. We illustrate this wide range of biological applications of CARS microscopy with a series of examples from our research.
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| 14. |
- Holtta-Vuori, M., et al.
(författare)
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Zebrafish: gaining popularity in lipid research
- 2010
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 429:2, s. 235-242
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Tidskriftsartikel (refereegranskat)abstract
- Zebrafish are an increasingly popular vertebrate model organism in which to study biological phenomena. It has been widely used, especially ill developmental biology and neurobiology, and many aspects of its development and physiology are similar to those of mammals. The popularity of zebrafish relies on its relatively low cost, rapid development and ease of genetic manipulation. Moreover, the optical transparency of the developing fish together with novel imaging techniques enable the direct visualization of complex phenomena at the level of the entire organism. This potential is now also being increasingly appreciated by the lipid research community. In the present review we summarize basic information on the lipid composition and distribution in zebrafish tissues, including lipoprotein metabolism, intestinal lipid absorption, the yolk lipids and their mobilization, as well as lipids in the nervous system. We also discuss studies in which zebrafish have been employed for the visualization of whole-body lipid distribution and trafficking. Finally, recent advances in using zebrafish as a model for lipid-related diseases, including atherosclerosis, obesity, diabetes and hepatic steatosis are highlighted. As the insights into zebrafish lipid metabolism increase, it is likely that zebrafish as a model organism will become an increasingly powerful tool in lipid research.
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| 15. |
- Kaldvee, Billy, et al.
(författare)
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Highly range-resolved ammonia detection using near-field picosecond differential absorption lidar
- 2012
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Ingår i: Optics Express. - 1094-4087. ; 20:18, s. 20688-20697
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Tidskriftsartikel (refereegranskat)abstract
- Ammonia detection is highly relevant for combustion in boilers and furnaces since NH3 is able to suppress nitric oxide levels by catalytic as well as non-catalytic reduction. The mixing of ammonia with flue gases is an important parameter to obtain efficient non-catalytic reduction. In this paper picosecond DIAL was used for range-resolved, single ended, NH3 detection, utilizing a tunable picosecond laser source. The absorption spectrum of the A(v(2) = 1)-> X(v(2) = 0) band was recorded and 212.2 and 214.5 nm was selected as the on-and off-resonance wavelength, respectively. One-dimensional concentration profiles with various NH3 concentration distributions are presented. The detection limit was found to be 40 ppm with a spatial resolution of 16 cm. (C) 2012 Optical Society of America
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| 16. |
- Kaldvee, Billy, et al.
(författare)
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LII-lidar: range-resolved backward picosecond laser-induced incandescence
- 2014
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 115:1, s. 111-121
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Tidskriftsartikel (refereegranskat)abstract
- A novel concept for remote in situ detection of soot emissions by a combination of laser-induced incandescence (LII) and light detection and ranging (lidar) is presented. A lidar setup based on a picosecond Nd:YAG laser and time-resolved signal detection in the backward direction was used for LII measurements in sooty premixed ethylene-air flames. Measurements of LII-lidar signal versus laser fluence and flame equivalence ratio showed good qualitative agreement with data reported in literature. The LII-lidar signal showed a decay consisting of two components, with lifetimes of typically 20 and 70 ns, attributed to soot sublimation and conductive cooling, respectively. Theoretical considerations and analysis of the LII-lidar signal showed that the derivative was proportional to the maximum value, which is an established measure of soot volume fraction. Utilizing this, differentiation of LII-lidar data gave profiles representing soot volume fraction with a range resolution of similar to 16 cm along the laser beam propagation axis. The accuracy of the evaluated LII-profiles was confirmed by comparison with LII-data measured simultaneously employing conventional right-angle detection. Thus, LII-lidar provides range-resolved single-ended detection, resourceful when optical access is restricted, extending the LII technique and opening up new possibilities for laser-based diagnostics of soot and other carbonaceous particles.
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| 17. |
- Kaldvee, Billy, et al.
(författare)
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Room-Fire Characterization Using Highly Range-Resolved Picosecond Lidar Diagnostics and CFD Simulations
- 2013
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Ingår i: Combustion Science and Technology. - : Informa UK Limited. - 1563-521X .- 0010-2202. ; 185:5, s. 749-765
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Tidskriftsartikel (refereegranskat)abstract
- In fire safety engineering, the use of computational fluid dynamics (CFD) allows for detailed multidimensional calculations of important parameters, for example, temperature. However, increasing use of CFD models puts requirements on experimental validation, a challenge for many measurement techniques under harsh fire conditions. In this work, laser-based picosecond light detection and ranging (ps-lidar) was used for remote measurements in a 1/2-scale ISO 9705 room containing either a methanol pool fire or a methane diffusion flame. Spatially resolved Rayleigh thermometry was conducted in the vertical door plane and in a horizontal plane inside the room. Temperatures obtained by ps-lidar are compared with values from thermocouples located in the doorway as well as results from CFD simulations. The technique allows for quantitative thermometry provided that minimal particle scattering interferences are present. Measurements of detailed distributions of temperature and particulates clearly demonstrate the potential of ps-lidar for diagnostics in large-scale combustion.
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| 18. |
- Martinez Avila, Hector, 1985, et al.
(författare)
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Mechanical stimulation of fibroblasts in micro-channeled bacterial cellulose scaffolds enhances production of oriented collagen fibers
- 2012
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Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 100A:4, s. 948-957
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose perforated by micro-channels (phi? similar to 500 mu m) has been investigated as a potential future scaffold material for meniscus implants. Scaffolds seeded with 3T6 fibroblasts were cultivated with mechanical stimulation in a compression bioreactor for enhanced collagen production. Constructs under dynamic compression at a frequency of 0.1 Hz and compression strain of 5% were compared to static cultures used as controls. The three-dimensional distributions of collagen fibers and fibroblasts in the cellulose scaffolds were studied under native, soft-matter conditions by combined second harmonic generation and coherent antiStokes Raman scattering microscopy, requiring no artificial sample preparation. Results showed that the micro-channels facilitated the alignment of cells and collagen fibers and that collagen production was enhanced by mechanical stimulation. Thus, cell-seeded, micro-channeled cellulose scaffolds provided guided tissue growth required to obtain an ultrastructure mimicking that of the meniscus.
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| 19. |
- Pohling, C., et al.
(författare)
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Chemical imaging of lignocellulosic biomass by CARS microscopy
- 2014
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Ingår i: Journal of Biophotonics. - : Wiley. - 1864-063X. ; 7:1-2, s. 126-134
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Tidskriftsartikel (refereegranskat)abstract
- Chemical and structural composition of wood biomass is studied by label-free and chemically specific Coherent Anti-Stokes Raman Scattering (CARS) microscopy. A concept developed for assignment and semi-quantitative imaging of sample components; cellulose, hemicellulose, and lignin; by multiplex CARS microspectroscopy and subsequent data analysis is presented. Specific imaging without fluorescence backround is achieved an order of magnitude faster compared with conventional Raman microscopy. Laser polarization control yield information on molecular arrangement in wood fibers. Narrowband CARS excitation of single vibrations allows for three-dimensional volume imaging. Thus, CARS microscopy has potential as an important instrument for characterization of lignocellulosic materials.
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| 20. |
- Rago, G., et al.
(författare)
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CARS microscopy for the visualization of micrometer-sized iron oxide MRI contrast agents in living cells
- 2011
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 2:9, s. 2470-2483
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Tidskriftsartikel (refereegranskat)abstract
- Micrometer-sized iron oxide particles (MPIOs) attract increasing interest as contrast agents for cellular tracking by clinical Magnetic Resonance Imaging (MRI). Despite the great potential of MPIOs for in vivo imaging of labeled cells, little is known on the intracellular localization of these particles following uptake due to the lack of techniques with the ability to monitor the particle uptake in vivo at single-cell level. Here, we show that coherent anti-Stokes Raman scattering (CARS) microscopy enables non-invasive, label-free imaging of MPIOs in living cells with sub-micron resolution in three dimensions. CARS allows simultaneous visualization of the cell framework and the MPIOs, where the particles can be readily distinguished from other cellular components of comparable dimensions, and localized inside the cell.
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| 21. |
- Svedberg, Fredrik, 1973, et al.
(författare)
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Nonlinear microscopy with fiber laser continuum excitation
- 2010
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1560-2281 .- 1083-3668. ; 15:2, s. Art. Nr. 026026-
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Tidskriftsartikel (refereegranskat)abstract
- A compact high-power fiber-based femtosecond laser system is presented for coherent anti-Stokes Raman scattering/second-harmonic generation (CARS/SHG) microscopy, and quantitatively compared with a conventional picosecond optical parametric oscillator (OPO)-based system. While the broad spectral width of the femtosecond pulses results in 2.5 times lower image contrast and limited spectral selectivity, lipid stores, myosin, and collagen filaments in living cells can clearly be identified at 60 times lower excitation powers compared to the picosecond system. Visually the images contain the same information. Together with simple operation, small footprint, and low cost, the capabilities of this high-power all-fiber-based laser system promise a more general use of nonlinear microscopy within the biosciences. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3374039]
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| 22. |
- Svensson, Emma, et al.
(författare)
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The Adiponectin Receptor Homologs in C-elegans Promote Energy Utilization and Homeostasis
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:6
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Tidskriftsartikel (refereegranskat)abstract
- Adiponectin is an adipokine with insulin-sensitising actions in vertebrates. Its receptors, AdipoR1 and AdipoR2, are PAQR-type proteins with 7-transmembrane domains and topologies reversed that of GPCR's, i.e. their C-termini are extracellular. We identified three adiponectin receptor homologs in the nematode C. elegans, named paqr-1, paqr-2 and paqr-3. These are differently expressed in the intestine (the main fat-storing tissue), hypodermis, muscles, neurons and secretory tissues, from which they could exert systemic effects. Analysis of mutants revealed that paqr-1 and -2 are novel metabolic regulators in C. elegans and that they act redundantly but independently from paqr-3. paqr-2 is the most important of the three paqr genes: mutants grow poorly, fail to adapt to growth at low temperature, and have a very high fat content with an abnormal enrichment in long (C20) poly-unsaturated fatty acids when combined with the paqr-1 mutation. paqr-2 mutants are also synthetic lethal with mutations in nhr-49, sbp-1 and fat-6, which are C. elegans homologs of nuclear hormone receptors, SREBP and FAT-6 (a Delta 9 desaturase), respectively. Like paqr-2, paqr-1 is also synthetic lethal with sbp-1. Mutations in aak-2, the C. elegans homolog of AMPK, or nhr-80, another nuclear hormone receptor gene, suppress the growth phenotype of paqr-2 mutants, probably because they restore the balance between energy expenditure and storage. We conclude that paqr-1 and paqr-2 are receptors that regulate fatty acid metabolism and cold adaptation in C. elegans, that their main function is to promote energy utilization rather than storage, and that PAQR class proteins have regulated metabolism in metazoans for at least 700 million years.
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| 23. |
- Åkeson, Madeleine, 1981, et al.
(författare)
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Chemical imaging of glucose by CARS microscopy
- 2010
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 41:12, s. 1348-1354
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Tidskriftsartikel (refereegranskat)abstract
- Glucose is one of the most fundamental molecules within life and bioengineering sciences. Present understanding of its role in cellular and bioengineering processes relies primarily on invasive, large-scale biochemical analysis, providing no spatial information on glucose pools or fluxes. This work identifies an emerging microscopy technique based on coherent anti-Stokes Raman scattering (CARS), which fulfills the need of quantitative imaging of glucose at the single-cell level with submicrometer resolution. No sample preparation with reporter molecules is required, ensuring that the low-weight metabolite is studied under natural conditions. The potential of CARS microscopy is illustrated by quantitatively mapping glucose fluxes and distributions in a microfluidic bioreactor and in lipid-bilayer vesicles, the latter as a model for glucose transmembrane transport. Furthermore, the metabolic response to a glucose pulse was monitored in living yeast cells. This study signifies a new era within CARS microscopy for its use of monitoring carbohydrates, in particular glucose which is one of the most abundant molecules in nature.
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