| 1. |
- Ayala, Maddalen, et al.
(författare)
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A supply-chain perspective on producing and upscaling bioplastic from cultivated brown seaweed
- 2024
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 444
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Tidskriftsartikel (refereegranskat)abstract
- Plastic pollution is an environmental emergency and finding sustainable alternatives to traditional plastics has become a pressing need. Seaweed-based bioplastic has emerged as a promising solution, as it is biodegradable and made from renewable biomass, while seaweed cultivation itself provides various environmental benefits. However, the feasibility of implementing a brown seaweed-based bioplastic supply chain in a realistic setting remains unclear, as previous research focused either on single processing steps or on virtual supply chains aggregating data from different studies. This study describes a case study for seaweed-based bioplastic within the PlastiSea research project: from seaweed cultivation to biomass processing and bioplastic and composite material development at the lab and pilot scale, thus providing insights into its feasibility. Adopting a multidisciplinary approach, the study employs multiple methods to characterize each stage in the supply chain and provides an overall life cycle assessment (LCA) as well as lessons learned throughout the process. The analysis showed potential for producing and utilizing multiple co-products from the same seaweed source, including biopolymer extracts with varying degrees of refinement for use in low-cost (bioplastic films) and high-cost (microfiber composites) applications. The use of residual biomass as a source of alginates for producing bioplastics offers a low-cost and sustainable biomass supply currently not competing with other markets. The LCA results indicate the potential for reducing the environmental impact of seaweed-based bioplastic production through upscaling and increasing process efficiency.
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| 2. |
- Hu, Yanlei, et al.
(författare)
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Composites of Silk Nanofibrils and Metal-Organic Framework Nanosheets for Fluorescence-Based Sensing and UV Shielding
- 2023
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society. - 2574-0970. ; 6:7, s. 6046-6055
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Tidskriftsartikel (refereegranskat)abstract
- Silk fibroin, a widely used natural biopolymer, presents remarkable flexibility and biodegradability, making it of great interest as a polymer matrix for functional composite materials. Herein, composites of silk nanofibrils and metal-organic framework (MOF) nanosheets were successfully fabricated by a coincubation and coassembly process. Under heat incubation, silk fibroin self-assembled into one-dimensional nanofibrils, while MOF nanosheets simultaneously covered or wrapped on the silk nanofibrils in a water suspension. Transparent composite membranes were obtained from their water suspensions by the solution casting method. The regenerated silk nanofibrils formed a network structure, and the integrated MOF nanosheets (0.1 to 3.0 wt %) endowed the composites with aggregation-induced emission luminogen (AIEgen)-based fluorescence. The fluorescence intensity of the composites was significantly enhanced owing to the interfacial interactions between silk nanofibrils and MOF nanosheets. The composite membranes also offer excellent UV shielding while maintaining optical transparency in the visible spectrum. This work provides an efficient pathway to fabricate luminescent silk protein-based composites for functional materials such as fluorescence sensing and anticounterfeiting.
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| 3. |
- Koskela, Salla, et al.
(författare)
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An Oxidative Enzyme Boosting Mechanical and Optical Performance of Densified Wood Films
- 2023
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Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 19:17
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Tidskriftsartikel (refereegranskat)abstract
- Nature has evolved elegant ways to alter the wood cell wall structure through carbohydrate-active enzymes, offering environmentally friendly solutions to tailor the microstructure of wood for high-performance materials. In this work, the cell wall structure of delignified wood is modified under mild reaction conditions using an oxidative enzyme, lytic polysaccharide monooxygenase (LPMO). LPMO oxidation results in nanofibrillation of cellulose microfibril bundles inside the wood cell wall, allowing densification of delignified wood under ambient conditions and low pressure into transparent anisotropic films. The enzymatic nanofibrillation facilitates microfibril fusion and enhances the adhesion between the adjacent wood fiber cells during densification process, thereby significantly improving the mechanical performance of the films in both longitudinal and transverse directions. These results improve the understanding of LPMO-induced microstructural changes in wood and offer an environmentally friendly alternative for harsh chemical treatments and energy-intensive densification processes thus representing a significant advance in sustainable production of high-performance wood-derived materials.
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| 4. |
- Koskela, Salla, et al.
(författare)
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Hemicellulose content affects the properties of cellulose nanofibrils produced from softwood pulp fibres by LPMO
- 2022
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Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270.
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Tidskriftsartikel (refereegranskat)abstract
- Lytic polysaccharide monooxygenase (LPMO)-catalysed oxidation of cellulose has emerged as a green alternative to chemical modifications in the production of cellulose nanofibrils (CNFs) from wood pulp fibres. The effect of the hemicellulose content of the starting pulp fibres on the oxidation capabilities of cellulose-active LPMO is important and has not been investigated previously. In this study, the production of LPMO-oxidised CNFs was evaluated on two commercial softwood pulp fibres with different hemicellulose contents. Thin and colloidally stable CNFs were readily obtained from kraft pulp with a hemicellulose content of 16%. The preserved hemicellulose fraction in the kraft pulp enhanced the access of LPMO into the fibre cell wall, enabling the production of homogeneous CNFs with a thin width of 3.7 ± 1.7 nm. By contrast, the LPMO-oxidised dissolving pulp with a lower hemicellulose content of 4% could only be partially disintegrated into thin CNFs, leaving a large amount of cellulose microfibril aggregates with widths of around 50 to 100 nm. CNFs disintegrated from the LPMO-oxidised kraft pulp could be processed into nanopapers with excellent properties including an optical transmittance of 86%, tensile strength of 260 MPa, and Young's modulus of 16.9 GPa. Such CNFs also showed acid-triggered nanofibril gelation owing to the introduced carboxyl groups on cellulose microfibril surfaces. These results indicate that the inherent hemicelluloses present in the wood cell wall are essential for LPMO-mediated CNF production from wood pulp fibres.
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| 7. |
- Koskela, Salla, et al.
(författare)
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Structure and Self-Assembly of Lytic Polysaccharide Monooxygenase-Oxidized Cellulose Nanocrystals
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 9:34, s. 11331-11341
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose-derived nanomaterial building blocks, including cellulose nanocrystals (CNCs), have become increasingly important in sustainable materials development. However, the preparation of CNCs requires hazardous chemicals to introduce surface charges that enable liquid crystalline phase behavior, a key parameter for obtaining self-organized, nanostructured materials from CNCs. Lytic polysaccharide monooxygenases (LPMOs), oxidative enzymes that introduce charged carboxyl groups on their cleavage sites in aqueous reaction conditions, offer an environmentally friendly alternative. In this work, two C1-oxidizing LPMOs from fungus Neurospora crassa, one of which contained a carbohydrate-binding module (CBM), were investigated for CNC preparation. The LPMO-oxidized CNCs shared similar features with chemical-derived CNCs, including colloidal stability and a needle-like morphology with typical dimensions of 7 ± 3 nm in width and 142 ± 57 nm in length for CBM-lacking LPMO-oxidized CNCs. The self-organization of the LPMO-oxidized CNCs was characterized in suspensions and solution cast films. Both LPMO-oxidized CNCs showed electrostatically driven self-organization in aqueous colloidal suspension and pseudo-chiral nematic ordering in solid films. The CBM-lacking LPMO generated a higher carboxyl content (0.70 mmol g–1), leading to a more uniform CNC self-organization, favoring LPMOs without CBMs for CNC production. The obtained results demonstrate production of stable colloidal CNCs with self-assembly by C1-oxidizing LPMOs toward a completely green production of advanced, nanostructured cellulose materials.
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| 8. |
- Li, Kai, et al.
(författare)
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Surface Functionalization of Spruce-Derived Cellulose Scaffold for Glycoprotein Separation
- 2021
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Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 8:19
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Tidskriftsartikel (refereegranskat)abstract
- Protein immobilization on a stationary phase, such as nanocelluloses, is widely used in biodiagnostic, biocatalytic, and bioseparation applications. With the top-down approach which utilizes the native hardwood honeycomb structure, mesoporous cellulose scaffolds can be fabricated without the need for energy-consuming production and bottom-up assembly of nanocelluloses. However, this approach is difficult for preparing softwood-based cellulose scaffolds due to the disintegration of wood cells after complete delignification. Herein, for the first time the use of spruce softwood with a homogenous cellular structure of longitudinally positioned and top-to-bottom joined tracheids is explored as a scaffold for protein immobilization. 1,4-butanediol diglycidyl ether is utilized to crosslink cell wall polysaccharides before the delignification step, thus improving the adhesion between tracheids. The native cellular structure of spruce is well preserved after the complete removal of lignin, enabling the successful production of a highly mesoporous and mechanically robust spruce-derived cellulose scaffold with exceptionally high specific surface area (219 m2 g−1). Further amination of the cellulose scaffold allows covalent immobilization of functional biomolecules, such as a lectin protein concanavalin A (Con A) and biotin, on the lumen surfaces and inside the porous cell wall. The Con A immobilized scaffold demonstrates native glycoprotein-binding activity and possible glycoprotein separation application.
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| 9. |
- Nokling-Eide, Katharina, et al.
(författare)
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Acid preservation of cultivated brown algae Saccharina latissima and Alaria esculenta and characterization of extracted alginate and cellulose
- 2023
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Ingår i: Algal Research. - : Elsevier BV. - 2211-9264. ; 71, s. 103057-
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Tidskriftsartikel (refereegranskat)abstract
- Cultivated brown algae represent an important potential source of carbohydrate polymers for packaging and other biobased materials. However, their exploitation is currently limited by a short harvest season and a lack of cost-effective and sustainable methods to preserve biopolymer quality. In the present study, cultivated Saccharina latissima (SL) and Alaria esculenta (AE) were preserved with formic acid at 4, 13 and 20 degrees C for up to 16 weeks prior to extraction and characterization of alginate and cellulose. The data show up to 40 % increased yield of alginate from preserved biomass compared with fresh and non-preserved biomass, primarily due to removal of minerals and other soluble compounds during the acid wash. Acid preservation and storage caused a reduction in alginate weight average molecular weight (Mw) that was mainly dependent on storage temperature and to a lesser extent on storage time; storage at 4 degrees C maintained the Mw of alginates at 350-500 kDa. Preservation had no effect on the guluronate block structure of the extracted alginates, but guluronic acid content and block length increased in the non-preserved samples, presumably due to enzymatic degradation of the alginate's M-rich re-gions. Preservation of the seaweed resulted in an increased cellulose yield compared with fresh and non -preserved biomass, again due to the biomass being reduced during acid wash. The molecular weight and crys-tallinity of cellulose were not altered by the process. Altogether our findings demonstrate that acid preservation at low temperatures can effectively stabilize seaweed biomass while preserving alginate and cellulose quality for biomaterials and other applications.
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