Chemical imaging of lignocellulosic biomass by CARS microscopy

Pohling, Christoph; Brackmann, Christian; Duarte, Alex Soares; Buckup, Tiago; Enejder, Annika; Motzkus, Marcus

doi:10.1002/jbio.201300052

Cited by 16 publications

(20 citation statements)

References 39 publications

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“…Glucan chains lack inversion symmetry and have previously been shown to give rise to SHG in starch (Brackmann et al 2011;Slepkov et al 2010) and cellulosic substrates of different origin Brown et al 2003;Glas et al 2015;Pohling et al 2014;Slepkov et al 2010;Zimmerley et al 2010). In order to interpret the SHG images of cellulosic substrates, the coherent nature of the SHG signal and the supramolecular structure of cellulose must be taken into account.…”

Section: Resultsmentioning

confidence: 99%

“…Coherent Raman scattering techniques, coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering, can probe molecular vibrations, allowing chemically sensitive imaging, for example to image carbohydrates and lignin in plant cell walls. Lignin is generally imaged by probing aromatic ring stretching vibration at 1600 cm -1 (Chen et al 2010;Ding et al 2012;Pohling et al 2014;Saar et al 2010;Zeng et al 2010), while polysaccharides can be imaged either by probing C-C and C-O stretching vibrations at *1100 cm -1 (Chen et al 2010;Saar et al 2010) or C-H stretching vibrations at *2900 cm -1 (Ding et al 2012;Pohling et al 2014;Zimmerley et al 2010). If full Raman spectrum is recorded, lignin and different types of polysaccharides can be distinguished using spectral fitting (Pohling et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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Visualization of structural changes in cellulosic substrates during enzymatic hydrolysis using multimodal nonlinear microscopy

et al. 2016

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Enzymatic hydrolysis of cellulose provides a renewable source of monosaccharides for production of variety of biochemicals and biopolymers. Unfortunately, the enzymatic hydrolysis of cellulose is often incomplete, and the reasons are not fully understood. We have monitored enzymatic hydrolysis in terms of molecular density, ordering and autofluorescence of cellulose structures in real time using simultaneous CARS, SHG and MPEF microscopy with the aim of contributing to the understanding and optimization of the enzymatic hydrolysis of cellulose. Three celluloserich substrates with different supramolecular structures, pulp fibre, acid-treated pulp fibre and Avicel, were studied at microscopic level. The microscopy studies revealed that before enzymatic hydrolysis Avicel had the greatest carbon-hydrogen density, while pulp fibre and acid-treated fibre had similar density. Monitoring of the substrates during enzymatic hydrolysis revealed the double exponential SHG decay for pulp fibre and acid-treated fibre indicating two phases of the process. Acid-treated fibre was hydrolysed most rapidly and the hydrolysis of pulp fibre was spatially non-uniform leading to fractioning of the particles, while the hydrolysis of Avicel was more than an order of magnitude slower than that of both fibres.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Visualization of structural changes in cellulosic substrates during enzymatic hydrolysis using multimodal nonlinear microscopy

et al. 2016

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“…Coherent anti-Stokes Raman (CARS) microscopy has been used to measure biomass, in part because it does not suffer from fluorescence interference, while still providing strong lignin signal [116,117]. Wild-type and transgenic alfalfa and corn stover were studied using CARS imaging [117].…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…Ultimately, reproducible, in situ measurements of lignin structure have been coveted for decades. Lignin structure Functionality specific reactions [40][41][42][43][44][47][48][49][50] CZE [52] APPI-MS [67] CRS Microscopy [116,117] AFM [178] GC [44] DFT [88,180] GCMS [171] DE-MS [62] Dispersive Raman [92][93][94][95][96] DSC [60] ClO 2 [45] GLC-FID [54] ESI/MS [77] Potentiometry [44] Modified oximation [46] GLC-MS [54] MALDI-MSI [68] Ellipsometry [179] Headspace GC [55] SEM [71,75] MALDI/TOF [73] Fluorescence [102,103,120,131,176,177] TEM [103] RP-HPLC [53] MBMS [75] FTIR [13,44,…”

Section: Wet Chemistrymentioning

confidence: 99%

Recent innovations in analytical methods for the qualitative and quantitative assessment of lignin

Lupoi

Singh

Parthasarathi

et al. 2015

Renewable and Sustainable Energy Reviews

297

188

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a b s t r a c tAs the attraction of creating biofuels and bio-based chemicals from lignocellulosic biomass has increased, researchers have been challenged with developing a better understanding of lignin structure, quantity and potential uses. Lignin has frequently been considered a waste-product from the deconstruction of plant cell walls, in attempts to isolate polysaccharides that can be hydrolyzed and fermented into fuel or other valuable commodities. In order to develop useful applications for lignin, accurate analytical instrumentation and methodologies are required to qualitatively and quantitatively assess, for example, what the structure of lignin looks like or how much lignin comprises a specific feedstock's cellular composition. During the past decade, various diverse strategies have been employed to elucidate the structure and composition of lignin. These techniques include using two-dimensional nuclear magnetic resonance to resolve overlapping spectral data, measuring biomass with vibrational spectroscopy to enable modeling of lignin content or monomeric ratios, methods to probe and quantify the linkages between lignin and polysaccharides, or refinements of established methods to provide higher throughput analyses, less use of consumables, etc. This review seeks to provide a comprehensive overview of many of the advancements achieved in evaluating key lignin attributes. Emphasis is placed on research endeavored in the last decade.

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“…The interpretation of scanned CARS spectra to indirectly assess unsaturation through the analysis of lipid packing, however, requires reliable monitoring of the excitation power. A more efficient approach than scanning each individual vibration would be to collect a full CARS spectrum using a white-light excitation source (Heinrich et al, 2008;Pohling et al, 2014). Rinia et al (2008) have exploited this possibility for 3T3-L1 cells (i.e.…”

Section: Cars Microspectroscopy Of Lipid Fluidity/unsaturationmentioning

confidence: 99%

Imaging of Lipids in Microalgae with Coherent Anti-Stokes Raman Scattering Microscopy

et al. 2015

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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) nitrogenstarved (NS) conditions. Good correlation (r 2 = 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 singlecell level along with important insights into lipid-accumulating mechanisms, here revealing two different modes for normal and excessive lipid accumulation.

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Chemical imaging of lignocellulosic biomass by CARS microscopy

Cited by 16 publications

References 39 publications

Visualization of structural changes in cellulosic substrates during enzymatic hydrolysis using multimodal nonlinear microscopy

Visualization of structural changes in cellulosic substrates during enzymatic hydrolysis using multimodal nonlinear microscopy

Recent innovations in analytical methods for the qualitative and quantitative assessment of lignin

Imaging of Lipids in Microalgae with Coherent Anti-Stokes Raman Scattering Microscopy

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