| 1. |
- Arcos-Hernandez, Monica, et al.
(författare)
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Thermoresponsive Glycopolymers Based on Enzymatically Synthesized Oligo-β-Mannosyl Ethyl Methacrylates and N-Isopropylacrylamide
- 2021
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 22:6, s. 2338-2351
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Tidskriftsartikel (refereegranskat)abstract
- We here present a series of thermoresponsive glycopolymers in the form of poly(N-isopropylacrylamide)-co-(2-[β-manno[oligo]syloxy] ethyl methacrylate)s. These copolymers were prepared from oligo-β-mannosyl ethyl methacrylates that were synthesized through enzymatic catalysis, and were subsequently investigated with respect to their aggregation and phase behavior in aqueous solution using a combination of 1H NMR spectroscopy, dynamic light scattering, cryogenic transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The thermoresponsive glycopolymers were prepared by conventional free radical copolymerizations of different mixtures of 2-(β-manno[oligo]syloxy)ethyl methacrylates (with either one or two saccharide units) and N-isopropyl acrylamide (NIPAm). The results showed that below the lower critical solution temperature (LCST) of poly(NIPAm), the glycopolymers readily aggregate into nanoscale structures, partly due to the presence of the saccharide moieties. Above the LCST of poly(NIPAm), the glycopolymers rearrange into a heterogeneous mixture of fractal and disc/globular aggregates. Cryo-TEM and SAXS data demonstrated that the presence of the pendant β-mannosyl moieties in the glycopolymers induces a gradual conformational change over a wide temperature range. Even though the onset of this transition is not different from the LCST of poly(NIPAm), this gradual conformational change offers a variation of the temperature-dependent properties in comparison to poly(NIPAm), which displays a sharp coil-to-globule transition. Importantly, the compacted form of the glycopolymers show a larger colloidal stability compared to the unmodified poly(NIPAm). In addition, the thermoresponsiveness can be conveniently tuned by varying the sugar unit-length and the oligo-β-mannosyl ethyl methacrylate content.
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| 2. |
- Badell, Maria Valldeperas, et al.
(författare)
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Lipid Sponge-Phase Nanoparticles as Carriers for Enzymes
- 2018
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Ingår i: Biophysical Journal. - : Cell Press. - 0006-3495 .- 1542-0086. ; 114:3, suppl 1, s. 15A-15A
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Immobilization of enzymes into different support materials has been widely studied as means to control their activity and stability. Here we will consider lipid liquid crystalline phases as enzyme carriers, as they have been demonstrated to have a high potential in a range of applications such as drug delivery, protein encapsulation or crystallization thanks to the wide range of self-assembly structures they can form, which have cavities of nano-scale dimensions. Furthermore, such structures have also been observed in a range of living organisms. Although, reverse cubic or hexagonal lipid aqueous phase can be used to entrap smaller biomolecules, it is still challenging to encapsulate bioactive macromolecules, such as proteins. Here, we will present a novel lipid system able to form highly swollen sponge phases (L3), with aqueous pores up to 13 nm of diameter. We will show that this structure is preserved even in excess aqueous solution, where they form sponge-like nanoparticles (L3 NPs) in which two enzymes of different sizes, Aspartic protease and beta-galactosidase (34 KDa and 460 KDa, respectively), could be included. To reveal the nature of the interaction between the enzymes and the lipid matrix, we studied the adsorption of both proteins on the lipid layers formed by the L3 NPs. The results will be discussed in terms of the ability of these nanoparticles to encapsulate and release of the proteins in the lipid matrix.
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| 3. |
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| 4. |
- Caputo, Fabio, 1996, et al.
(författare)
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Investigating the role of AA9 LPMOs in enzymatic hydrolysis of differentially steam-pretreated spruce
- 2023
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Ingår i: Biotechnology for Biofuels and Bioproducts. - 2731-3654. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: To realize the full potential of softwood-based forest biorefineries, the bottlenecks of enzymatic saccharification of softwood need to be better understood. Here, we investigated the potential of lytic polysaccharide monooxygenases (LPMO9s) in softwood saccharification. Norway spruce was steam-pretreated at three different severities, leading to varying hemicellulose retention, lignin condensation, and cellulose ultrastructure. Hydrolyzability of the three substrates was assessed after pretreatment and after an additional knife-milling step, comparing the efficiency of cellulolytic Celluclast + Novozym 188 and LPMO-containing Cellic CTec2 cocktails. The role of Thermoascus aurantiacus TaLPMO9 in saccharification was assessed through time-course analysis of sugar release and accumulation of oxidized sugars, as well as wide-angle X-ray scattering analysis of cellulose ultrastructural changes. Results: Glucose yield was 6% (w/w) with the mildest pretreatment (steam pretreatment at 210 °C without catalyst) and 66% (w/w) with the harshest (steam pretreatment at 210 °C with 3%(w/w) SO2) when using Celluclast + Novozym 188. Surprisingly, the yield was lower with all substrates when Cellic CTec2 was used. Therefore, the conditions for optimal LPMO activity were tested and it was found that enough O2 was present over the headspace and that the reducing power of the lignin of all three substrates was sufficient for the LPMOs in Cellic CTec2 to be active. Supplementation of Celluclast + Novozym 188 with TaLPMO9 increased the conversion of glucan by 1.6-fold and xylan by 1.5-fold, which was evident primarily in the later stages of saccharification (24–72 h). Improved glucan conversion could be explained by drastically reduced cellulose crystallinity of spruce substrates upon TaLPMO9 supplementation. Conclusion: Our study demonstrated that LPMO addition to hydrolytic enzymes improves the release of glucose and xylose from steam-pretreated softwood substrates. Furthermore, softwood lignin provides enough reducing power for LPMOs, irrespective of pretreatment severity. These results provided new insights into the potential role of LPMOs in saccharification of industrially relevant softwood substrates.
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| 5. |
- Caputo, Fabio, 1996, et al.
(författare)
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Understanding the impact of steam pretreatment severity on cellulose ultrastructure, recalcitrance, and hydrolyzability of Norway spruce
- 2022
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Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- The efficient use of softwood in biorefineries requires harsh pretreatment conditions to overcome biomass recalcitrance. Following harsh pretreatments, the hemicellulose is solubilized. Here, we studied the material characteristics of Norway spruce following steam pretreatment at six different severities, relating chemical and structural information to the enzymatic hydrolyzability. Steam pretreatment conditions were defined by two different temperatures (180 °C and 210 °C), with and without the addition of various acids (CH3COOH, H3PO4, H2SO4, SO2). Structural knowledge of the streams is a cornerstone for developing an efficient saccharification process. This study combines advanced structural characterizations to gain fundamental understanding of the influence of severity of pretreatment on spruce. Structural knowledge is a cornerstone in developing an effective saccharification process by modulating pretreatment conditions and enzymes employed. Overall structural properties were assessed by scanning electron microscopy. The effect of stream pretreatment severity on lignin and lignin-carbohydrate bonds was investigated by two-dimensional heteronuclear single quantum correlation nuclear magnetic resonance. Finally, cellulose ultrastructure was studied by applying small/wide-angle X-ray scattering. The structural characteristics of the six pretreated softwood substrates were related to the enzymatic hydrolyzability. With increasing pretreatment severity, surface defibrillation, and lignin depolymeryzation were observed. Further, lignin-carbohydrate complexes signals were detected. Cellulose analysis revealed the rearrangement of microfibrils leading to the formation of larger microfibril aggregates. This microfibril rearrangement likely contributed to the observed increase in enzymatic hydrolysis yields as better enzyme accessibility resulted.
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| 6. |
- Gonçalves, Rui A., et al.
(författare)
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Facile control of surfactant lamellar phase transition and adsorption behavior
- 2020
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 10:31, s. 18025-18034
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Tidskriftsartikel (refereegranskat)abstract
- This study sets out to investigate the effect of the presence of small water-soluble additives on the tunability of the surfactant gel-to-liquid crystalline (Lß-La) phase transition temperature (Tm) for a bilayer-forming cationic surfactant and the phase behavior of such surfactant systems on dilution. This is strongly driven by the fact that this type of cationic surfactant has many interesting unanswered scientific questions and has found applications in various areas such as consumer care, the petrochemical industry, food science,etc.The underlying surfactant/additive interactions and the interfacial behavior of lamellar surfactant systems including the surfactant deposition on surfaces can provide new avenues to develop novel product formulations. We have examined dioctadecyldimethyl ammonium chloride (DODAC) in the presence of small polar additives, with respect to the phase behavior upon dilution and the deposition on silica. Differential scanning calorimetry (DSC) is used to track the transition temperature,Tm, and synchrotron and laboratory-based small and wide-angle X-ray scattering (SAXS and WAXS) were used to determine the self-assembled surfactant structure below and above theTm. DSC scans showed that upon dilution the additives could be removed from the surfactant bilayer which in turn tuned theTm. A spontaneous transition from a liquid crystalline (La) phase to a gel (Lß) phase on dilution was demonstrated, which indicated that additives could be taken out from the Laphase. By means ofin situnull ellipsometry, the deposition of a diluted surfactant Lßphase upon replacement of bulk solution by deionized water was followed. This technique enables time-resolved monitoring of the deposited surfactant layer thickness and adsorbed amount, which allows us to understand the deposition on surfaces. Robust layers at least one bilayer-thick were deposited onto the surface and shown to be irreversibly adsorbed due to poor surfactant solvency in water. The thickest layer of surfactant deposited after dilution was found for mixtures with small amounts of additive since high amounts might lead to a phase-separated system.
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| 7. |
- Lidén, Anna, 1994, et al.
(författare)
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Structure of Filter Cakes during the Electroassisted Filtration of Microfibrillated Cellulose
- 2022
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 61:43, s. 16247-16256
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Tidskriftsartikel (refereegranskat)abstract
- Microfibrillated cellulose (MFC) is a biobased material with unique properties that can be used in a multitude of applications. Water removal from the dilute product streams is, however, challenging and hinders its commercial attractiveness. One possible method of improving dewatering is the use of electroassisted filtration, in which an electric field is applied across part of the filter chamber. In this work, a bench-scale dead-end filter press, modified to allow for electroassisted filtration, was used to dewater a suspension of MFC produced via 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation. A filter cake was produced with a channeled structure related to the design of the anode mesh, indicating that the cellulose microfibrils were aligned in the direction of the electric field. This was investigated, qualitatively and quantitively, using scanning electron microscopy and wide-angle X-ray scattering, which showed a preferred orientation on a microscopic level but only a partial orientation on a molecular level (fc between 0.49 and 0.57). The influence of the density of the anode mesh, in terms of the structure/permeability of the filter cake and dewatering rate, was also evaluated using two different anode mesh densities (5 × 5 and 10 × 10 mm). It was not, however, found to have any major impact on the dewatering rate.
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| 8. |
- Morrill, Johan, et al.
(författare)
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β-Mannanase-catalyzed synthesis of alkyl mannooligosides
- 2018
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 102:12, s. 5149-5163
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Tidskriftsartikel (refereegranskat)abstract
- β-Mannanases catalyze the conversion and modification of β-mannans and may, in addition to hydrolysis, also be capable of transglycosylation which can result in enzymatic synthesis of novel glycoconjugates. Using alcohols as glycosyl acceptors (alcoholysis), β-mannanases can potentially be used to synthesize alkyl glycosides, biodegradable surfactants, from renewable β-mannans. In this paper, we investigate the synthesis of alkyl mannooligosides using glycoside hydrolase family 5 β-mannanases from the fungi Trichoderma reesei (TrMan5A and TrMan5A-R171K) and Aspergillus nidulans (AnMan5C). To evaluate β-mannanase alcoholysis capacity, a novel mass spectrometry-based method was developed that allows for relative comparison of the formation of alcoholysis products using different enzymes or reaction conditions. Differences in alcoholysis capacity and potential secondary hydrolysis of alkyl mannooligosides were observed when comparing alcoholysis catalyzed by the three β-mannanases using methanol or 1-hexanol as acceptor. Among the three β-mannanases studied, TrMan5A was the most efficient in producing hexyl mannooligosides with 1-hexanol as acceptor. Hexyl mannooligosides were synthesized using TrMan5A and purified using high-performance liquid chromatography. The data suggests a high selectivity of TrMan5A for 1-hexanol as acceptor over water. The synthesized hexyl mannooligosides were structurally characterized using nuclear magnetic resonance, with results in agreement with their predicted β-conformation. The surfactant properties of the synthesized hexyl mannooligosides were evaluated using tensiometry, showing that they have similar micelle-forming properties as commercially available hexyl glucosides. The present paper demonstrates the possibility of using β-mannanases for alkyl glycoside synthesis and increases the potential utilization of renewable β-mannans.
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| 9. |
- Naidjonoka, Polina, et al.
(författare)
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Bicontinuous cubic liquid crystalline phase nanoparticles stabilized by softwood hemicellulose
- 2021
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765. ; 203
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Tidskriftsartikel (refereegranskat)abstract
- The colloidal stability of lipid based cubosomes, aqueous dispersion of inverse bicontinuous cubic phase, can be significantly increased by a stabilizer. The most commonly used stabilizers are non-ionic tri-block copolymers, poloxamers, which adsorb at the lipid-water interface and hence sterically stabilize the dispersion. One of the challenges with these synthetic polymers is the effect on the internal structure of the cubosomes and the potential toxicity when these nanoparticles are applied as nanomedicine platforms. The natural polysaccharide, softwood hemicellulose, has been proved to be an excellent stabilizer for oil-in-water emulsions, partially due to the presence of hydrophobic lignin in the extract which to some extent is associated to hemicellulose. Herein, we reported for the first time cubosomes stabilized by two types of softwood hemicelluloses, where one is extracted through thermomechanical pulping (TMP, low lignin content) and the other obtained from sodium-based sulfite liquor (SSL, high lignin content). The effect of the two hemicellulose samples on the colloidal stability and structure of monoolein-based cubosomes have been investigated via DLS, SAXS, AFM and cryo-TEM. The data obtained suggest that both types of the hemicelluloses stabilize monoolein (GMO) based cubosomes in water without significantly affecting their size, morphology and inner structure. SSL-extracted hemicellulose yields the most stable cubosomes, likely due to the higher content of lignin in comparison to TMP-stabilized ones. In addition, the stability of these particles was tested under physiological conditions relevant to possible application as drug carriers.
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| 10. |
- Naidjonoka, Polina, et al.
(författare)
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On the interaction of softwood hemicellulose with cellulose surfaces in relation to molecular structure and physicochemical properties of hemicellulose
- 2020
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 16:30, s. 7063-7076
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Tidskriftsartikel (refereegranskat)abstract
- The substantial part of the water-soluble hemicellulose fraction, obtained when processing cellulose to produce paper and other products, has so far been discarded. The aim of this work is to reveal the interfacial properties of softwood hemicellulose (galactoglucomannan, GGM) in relation to their molecular and solution structure. In this study the sugar composition of GGM was characterised by chemical analysis as well as 1D and 2D NMR spectroscopy. Previously it has been demonstrated that hemicellulose has high affinity towards cellulose and has the ability to alter the properties of cellulose based products. This study is focused on the interactions between hemicellulose and the cellulose surface. Therefore, adsorption to hydrophobized silica and cellulose surfaces of two softwood hemicellulose samples and structurally similar seed hemicelluloses (galactomannans, GMs) was studied with ellipsometry, QCM-D and neutron reflectometry. Aqueous solutions of all samples were characterized with light scattering to determine how the degree of side-group substitution and molecular weight affect the conformation and aggregation of these polymers in the bulk. In addition, hemicellulose samples were studied with SAXS to investigate backbone flexibility. Light scattering results indicated that GM polymers form globular particles while GGMs were found to form rod-like aggregates in the solution. The polysaccharides exhibit higher adsorption to cellulose than on hydrophobic surfaces. A clear correlation between the increase in molecular weight of polysaccharides and increasing adsorbed amount on cellulose was observed, while the adsorbed amount on the hydrophobic surface was fairly independent of the molecular weight. The obtained layer thickness was compared with bulk scattering data and the results indicated flat conformation of the polysaccharides on the surface.
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| 11. |
- Naidjonoka, Polina
(författare)
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On the physico-chemical properties of softwood hemicellulose and compounds derived from it
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hemicellulose is the second largest polysaccharide group available in nature after cellulose. Hemicellulose is present in plant cell walls along with cellulose and lignin. It is an abundant and biodegradable material that could potentially replace fossil-based products. The focus of this thesis is the properties and valorization of softwood hemicellulose (galactoglucomannan).In the first part of the thesis, the nature of the interactions between hemicellulose and cellulose was investigated. The adsorption studies of several types of hemicelluloses to cellulose model surfaces were performed using ellipsometry, QCM-D and neutron reflectometry. The results showed that the binding between hemicellulose and cellulose involves specific interactions facilitated by similarity in the backbone unit conformation. The adsorption showed the molecular weight dependency with the largest adsorbed amount obtained for a hemicellulose with the largest molecular weight at a low concentration regime. The opposite trend was observed at higher concentrations. Neutron reflectometry results demonstrated that lower molecular weight hemicellulose samples with higher flexibility were able to more extensively diffuse into the amorphous parts of the cellulose layer.In the second part of this work, the properties of various hemicellulose-based colloidal systems were evaluated. Softwood hemicellulose extract provided excellent stabilizing effect to lipid liquid crystalline phase nanoparticles. These nanoparticles showed high colloidal stability over the period of at least 42 days with no major changes in the hydrodynamic diameter and the polydispersity index.Inclusion of mannans derived from hemicellulose in the structure of thermoresponsive NIPAm-based copolymers shifted the transition temperature to higher values. Mannan side groups were here suggested to create a hydrophilic shell around the hydrophobic particle that provided a stabilizing effect at the elevated temperatures up to 70°C.Finally, the hemicellulose-based surfactant mixture demonstrated surface active properties with formation of two separate kinds of micelles as evidenced by the two inflection points in the surface tension curve.
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