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Estimation of syringyl units in wood lignins by FT-Raman spectroscopy
摘要： Syringyl (S) lignin content and syringyl-to-guaiacyl (S/G) lignin ratio are important characteristics of wood and lignocellulosic biomass. Although numerous methods are available for estimating S lignin units and S/G ratio, in this work, a new method based on Raman spectroscopy that uses the 370 cm-1 Raman band-area intensity (370-area) was developed. The reliability of the Raman approach for determining S content was first tested by the quantitative analysis of three syringyl lignin models by sampling them, separately, in dioxane and in Avicel. Good linear correlations between the 370 cm-1 intensity and model concentrations were obtained. Next, the %S lignin units in various woods were measured by correlating the 370 cm-1 Raman intensity data with values of S units in lignin determined by three regularly used methods – thioacidolysis, DFRC, and 2D-HSQC NMR. The former two methods take into account only the monomers cleaved from β–O–4-linked lignin units whereas the NMR method reports S content on the whole cell wall lignin. When the 370-area intensities and %S values from the regularly used methods were correlated, good linear correlations were obtained (R2 = 0.767, 0.731, and 0.804, respectively, for the three methods). The correlation with the highest R2, i.e., with the 2D NMR method, is being proposed for estimating S units in wood lignins by Raman spectroscopy as, in principle, both represent of the whole cell wall lignin and not just the portion of lignin that gets cleaved to release monomers. The Raman analysis method is quick, uses minimal harmful chemicals, carried out nondestructively, and is insensitive to the wet or dry state of the sample. The only limitations are that a sample of wood contain at least 30% S and not be significantly fluorescent, although the latter can be mitigated in some cases.
关键词： NMR,Cell wall,%S,Thioacidolysis,S/G ratio,DFRC
更新于2025-11-14 15:16:37
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Development of titania-integrated silica cell walls of the titanium-resistant diatom, <i>Fistulifera solaris</i>
摘要： We report the biological synthesis of titania that is integrated into the silica-based cell walls of a titanium-resistant diatom, Fistulifera solaris. Titania is deposited across the diatom cell walls by simply incubating F. solaris in a culture medium containing a high concentration (2 mM) of a water-soluble organo-titanium compound, titanium(IV) bis(ammonium lactato) dihydroxide (TiBALDH) that would otherwise inhibit the growth of other diatom species. Furthermore, we genetically engineered the interfaces of the diatom cell walls with a titanium-associated peptide, which subsequently increased the Ti/Si atomic ratio by more than 50% (i.e., from 6.2 ± 0.2 % to 9.7 ± 0.5 %, as identified by inductively coupled plasma-atomic emission spectrometry). The titanium content on the F. solaris silica cell walls is one of the highest reported to date, and comparable to that of chemically synthesized TiO2-silica composites. Subsequent thermal annealing at 500°C in air converted the wall-bound titania to nanocrystalline anatase TiO2, a highly photocatalytically active phase. We propose that incubation of the titanium-resistant F. solaris with TiBALDH as demonstrated in this study could be a promising bioprocess towards the scalable synthesis of TiO2. In addition, the genetic engineering we used to modulate the surface properties of diatom silica cell walls could be extended to synthesize controlled nanomaterials for multiple applications including bioremediation, water purification, and energy conversion/storage.
关键词： Genetic engineering,silica cell wall,TiO2,Fistulifera solaris,diatom
更新于2025-09-23 15:21:21
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Influence of fungal infection on plant tissues: FTIR detects compositional changes to plant cell walls
摘要： Compositional change in plant cell walls as a result of infection by non-host (putative) endophytes and a host pathogen were studied by quantifying plant cell wall degrading enzymes (CWDEs) produced by these fungi, and by detecting cell wall changes via Fourier Transform Infrared spectroscopy (FTIR) and relative lignin/carbohydrate intensity ratios. Oil palm ramets were first inoculated with homogenized fungal suspension. The treated fungal suspensions were assayed for CWDEs whereas the ramets were powderized for FTIR analysis. Results revealed that putative endophytes and host pathogen expressed all CWDEs, suggesting their probable roles in infection and colonization. Following inoculation, plant cell wall composition showed missing dips in spectra depicting changes to carbohydrate, xylan and lignin constituents. The indistinguishable FTIR spectra for putative endophyte-inoculated and pathogen-inoculated ramets suggest that both endophytes and pathogen have elicited similar responses to plant cell walls. Relative lignin/carbohydrate ratios further demonstrated that the putative endophytes did not breakdown lignin and carbohydrate, further exemplifying the non-pathogenic and asymptomatic infection by the endophytes. This study presents the influence of putative endophytes on plant tissues of oil palm, and how this compared to pathogenic infection.
关键词： FTIR,Endophytes,Detection,Colonization,Ganoderma boninense,Cell wall
更新于2025-09-23 15:21:21
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Quantum dots are conventionally applicable for wide-profiling of wall polymer distribution and destruction in diverse cells of rice
摘要： Plant cell walls represent enormous biomass resources for biofuels, and it thus becomes important to establish a sensitive and wide-applicable approach to visualize wall polymer distribution and destruction during plant growth and biomass process. Despite quantum dots (QDs) have been applied to label biological specimens, little is reported about its application in plant cell walls. Here, semiconductor QDs (CdSe/ZnS) were employed to label the secondary antibody directed to the epitopes of pectin or xylan, and sorted out the optimal conditions for visualizing two polysaccharides distribution in cell walls of rice stem. Meanwhile, the established QDs approach could simultaneously highlight wall polysaccharides and lignin co-localization in different cell types. Notably, this work demonstrated that the QDs labeling was sensitive to profile distinctive wall polymer destruction between alkali and acid pretreatments with stem tissues of rice. Hence, this study has provided a powerful tool to characterize wall polymer functions in plant growth and development in vivo, as well as their distinct roles during biomass process in vitro.
关键词： Glycan immunolabeling,Plant cell wall,Biomass,Rice,Quantum dots,Chemical pretreatment
更新于2025-09-19 17:13:59
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Ultra-short Echo Time Imaging with Multiple Echo Refocusing for Porous Media T2 Mapping
摘要： T2 relaxation time measurement is a powerful tool to distinguish signal components in porous media. As T2 weighting is generally achieved by spin-echo based methods, it is very challenging to capture very short T2 relaxation time components, approximately 1 ms, with high resolution spatial encoding. It is especially challenging when T2 relaxation times of the other signal components are not known a priori. We propose a method, combining ultrashort echo time (UTE) imaging with multiple spin echo refocusing, to generate a series of images with T2 weighting. The T2 decay curves for each image voxel were extracted, and multiple T2 relaxation components were quantitatively evaluated. The method has been applied to a fast relaxation system, namely, moisture content in wood samples to differentiate cell wall (bound) water and cell cavity (lumen) water.
关键词： cell wall water,spin echo,wood,T2 mapping,lumen water,k-space,radial,UTE
更新于2025-09-09 09:28:46