| 1. |
- Abbasi-Ravasjani, Sonia, et al.
(författare)
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Sulfated carboxymethyl cellulose and carboxymethyl kappa-carrageenan immobilization on 3D-printed poly-epsilon-caprolactone scaffolds differentially promote pre-osteoblast proliferation and osteogenic activity
- 2022
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media SA. - 2296-4185. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- The lack of bioactivity in three-dimensional (3D)-printing of poly-epsilon-caprolactone (PCL) scaffolds limits cell-material interactions in bone tissue engineering. This constraint can be overcome by surface-functionalization using glycosaminoglycan-like anionic polysaccharides, e.g., carboxymethyl cellulose (CMC), a plant-based carboxymethylated, unsulfated polysaccharide, and kappa-carrageenan, a seaweed-derived sulfated, non-carboxymethylated polysaccharide. The sulfation of CMC and carboxymethylation of kappa-carrageenan critically improve their bioactivity. However, whether sulfated carboxymethyl cellulose (SCMC) and carboxymethyl kappa-carrageenan (CM-kappa-Car) affect the osteogenic differentiation potential of pre-osteoblasts on 3D-scaffolds is still unknown. Here, we aimed to assess the effects of surface-functionalization by SCMC or CM-kappa-Car on the physicochemical and mechanical properties of 3D-printed PCL scaffolds, as well as the osteogenic response of pre-osteoblasts. MC3T3-E1 pre-osteoblasts were seeded on 3D-printed PCL scaffolds that were functionalized by CM-kappa-Car (PCL/CM-kappa-Car) or SCMC (PCL/SCMC), cultured up to 28 days. The scaffolds' physicochemical and mechanical properties and pre-osteoblast function were assessed experimentally and by finite element (FE) modeling. We found that the surface-functionalization by SCMC and CM-kappa-Car did not change the scaffold geometry and structure but decreased the elastic modulus. Furthermore, the scaffold surface roughness and hardness increased and the scaffold became more hydrophilic. The FE modeling results implied resilience up to 2% compression strain, which was below the yield stress for all scaffolds. Surface-functionalization by SCMC decreased Runx2 and Dmp1 expression, while surface-functionalization by CM-kappa-Car increased Cox2 expression at day 1. Surface-functionalization by SCMC most strongly enhanced pre-osteoblast proliferation and collagen production, while CM-kappa-Car most significantly increased alkaline phosphatase activity and mineralization after 28 days. In conclusion, surface-functionalization by SCMC or CM-kappa-Car of 3D-printed PCL-scaffolds enhanced pre-osteoblast proliferation and osteogenic activity, likely due to increased surface roughness and hydrophilicity. Surface-functionalization by SCMC most strongly enhanced cell proliferation, while CM-kappa-Car most significantly promoted osteogenic activity, suggesting that surface-functionalization by CM-kappa-Car may be more promising, especially in the short-term, for in vivo bone formation.
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| 2. |
- Agustin, Melissa B., et al.
(författare)
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Enzymatic crosslinking of lignin nanoparticles and nanocellulose in cryogels improves adsorption of pharmaceutical pollutants
- 2024
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 266
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Tidskriftsartikel (refereegranskat)abstract
- Pharmaceuticals, designed for treating diseases, ironically endanger humans and aquatic ecosystems as pollutants. Adsorption-based wastewater treatment could address this problem, however, creating efficient adsorbents remains a challenge. Recent efforts have shifted towards sustainable bio-based adsorbents. Here, cryogels from lignin-containing cellulose nanofibrils (LCNF) and lignin nanoparticles (LNPs) were explored as pharmaceuticals adsorbents. An enzyme-based approach using laccase was used for crosslinking instead of fossil-based chemical modification. The impact of laccase treatment on LNPs alone produced surface-crosslinked water-insoluble LNPs with preserved morphology and a hemicellulose-rich, water-soluble LNP fraction. The water-insoluble LNPs displayed a significant increase in adsorption capacity, up to 140 % and 400 % for neutral and cationic drugs, respectively. The crosslinked cryogel prepared by one-pot incubation of LNPs, LCNF and laccase showed significantly higher adsorption capacities for various pharmaceuticals in a multi-component system than pure LCNF or unmodified cryogels. The crosslinking minimized the leaching of LNPs in water, signifying enhanced binding between LNPs and LCNF. In real wastewater, the laccase-modified cryogel displayed 8–44 % removal for cationic pharmaceuticals. Overall, laccase treatment facilitated the production of bio-based adsorbents by improving the deposition of LNPs to LCNF. Finally, this work introduces a sustainable approach for engineering adsorbents, while aligning with global sustainability goals.
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| 3. |
- Agustin, Melissa B., et al.
(författare)
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Lignin nanoparticle-decorated nanocellulose cryogels as adsorbents for pharmaceutical pollutants
- 2023
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 330
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption is a relatively simple wastewater treatment method that has the potential to mitigate the impacts of pharmaceutical pollution. This requires the development of reusable adsorbents that can simultaneously remove pharmaceuticals of varying chemical structure and properties. Here, the adsorption potential of nanostructured wood-based adsorbents towards different pharmaceuticals in a multi-component system was investigated. The adsorbents in the form of macroporous cryogels were prepared by anchoring lignin nanoparticles (LNPs) to the nanocellulose network via electrostatic attraction. The naturally anionic LNPs were anchored to cationic cellulose nanofibrils (cCNF) and the cationic LNPs (cLNPs) were combined with anionic TEMPO-oxidized CNF (TCNF), producing two sets of nanocellulose-based cryogels that also differed in their overall surface charge density. The cryogels, prepared by freeze-drying, showed layered cellulosic sheets randomly decorated with spherical lignin on the surface. They exhibited varying selectivity and efficiency in removing pharmaceuticals with differing aromaticity, polarity and ionic characters. Their adsorption potential was also affected by the type (unmodified or cationic), amount and morphology of the lignin nanomaterials, as well as the pH of the pharmaceutical solution. Overall, the findings revealed that LNPs or cLNPs can act as functionalizing and crosslinking agents to nanocellulose-based cryogels. Despite the decrease in the overall positive surface charge, the addition of LNPs to the cCNF-based cryogels showed enhanced adsorption, not only towards the anionic aromatic pharmaceutical diclofenac but also towards the aromatic cationic metoprolol (MPL) and tramadol (TRA) and neutral aromatic carbamazepine. The addition of cLNPs to TCNF-based cryogels improved the adsorption of MPL and TRA despite the decrease in the net negative surface charge. The improved adsorption was attributed to modes of removal other than electrostatic attraction, and they could be 7C-7C aromatic ring or hydrophobic interactions brought by the addition of LNPs or cLNPs. However, significant improvement was only found if the ratio of LNPs or cLNPs to nanocellulose was 0.6:1 or higher and with spherical lignin nanomaterials. As crosslinking agents, the LNPs or cLNPs affected the rheological behavior of the gels, and increased the firmness and decreased the water holding capacity of the corresponding cryogels. The resistance of the cryogels towards disintegration with exposure to water also improved with crosslinking, which eventually enabled the cryogels, especially the TCNF-based one, to be regenerated and reused for five cycles of adsorption-desorption experiment for the model pharmaceutical MPL. Thus, this study opened new opportunities to utilize LNPs in providing nanocellulose-based adsorbents with additional functional groups, which were otherwise often achieved by rigorous chemical modifications, at the same time, crosslinking the nanocellulose network.
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| 4. |
- Agustin, Melissa B., et al.
(författare)
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Lignin nanoparticles as co-stabilizers and modifiers of nanocellulose-based Pickering emulsions and foams
- 2023
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Ingår i: Cellulose. - : Springer Nature. - 0969-0239 .- 1572-882X. ; 30:14, s. 8955-8971
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Tidskriftsartikel (refereegranskat)abstract
- Nanocellulose is very hydrophilic, preventing interactions with the oil phase in Pickering emulsions. This limitation is herein addressed by incorporating lignin nanoparticles (LNPs) as co-stabilizers of nanocellulose-based Pickering emulsions. LNP addition decreases the oil droplet size and slows creaming at pH 5 and 8 and with increasing LNP content. Emulsification at pH 3 and LNP cationization lead to droplet flocculation and rapid creaming. LNP application for emulsification, prior or simultaneously with nanocellulose, favors stability given the improved interactions with the oil phase. The Pickering emulsions can be freeze–dried, enabling the recovery of a solid macroporous foam that can act as adsorbent for pharmaceutical pollutants. Overall, the properties of nanocellulose-based Pickering emulsions and foams can be tailored by LNP addition. This strategy offers a unique, green approach to stabilize biphasic systems using bio-based nanomaterials without tedious and costly modification procedures.
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| 5. |
- Berglund, Lars A., 1956-, et al.
(författare)
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Eco-friendly high-strength composites based on hot-pressed lignocellulose microfibrils or fibers
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society. - 2168-0485. ; 9:4, s. 1899-1910
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Tidskriftsartikel (refereegranskat)abstract
- Unbleached lignocellulosic wood fiber materials of low porosity are of great interest as eco-friendly load-bearing materials because their yield is much higher than that for “pure” wood cellulosics. The difference between comparable materials based on lignocellulose fibers or nanocellulose is investigated. The structure, surface area, mechanical properties, moisture sorption, and optical properties of films based on fibers or microfibrillated lignocellulose (MFLC) were characterized as a function of lignin content, and the environmental impact was compared. The modulus and tensile strength of comparable fiber and MFLC films (≈25% porosity) increased up to an optimum lignin content (11−17%) and then decreased at a very high lignin content. Hot-pressed MFLC films with little porosity showed excellent properties, 230−260 MPa strength, 17−20 GPa modulus, and 81 MPa wet strength. The mechanical property values of hot-pressed wood fibers with 25% porosity were also as high as 154 MPa strength and 13.2 GPa modulus, which are higher than those of comparable materials reported in the literature. Because hot-pressed lignocellulose fibers can be readily recycled and show low cumulative energy demand, they are candidates for semistructural engineering materials. MFLC is of great interest for coatings, films, adhesives, and as additives or in high-technology applications.
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| 6. |
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| 7. |
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| 8. |
- Jungstedt, Erik, et al.
(författare)
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Mechanical behavior of all-lignocellulose composites—Comparing micro- and nanoscale fibers using strain field data and FEM updating
- 2022
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Ingår i: Composites. Part A, Applied science and manufacturing. - : Elsevier BV. - 1359-835X .- 1878-5840. ; 161, s. 107095-107095
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Tidskriftsartikel (refereegranskat)abstract
- Hot-pressed, binder-free wood fiber (WF) composites can serve as load-bearing and eco-friendly materials, and the comparison of nanoscale fibril reinforcement with microscale wood fibers is of interest. We investigated property differences and interpreted deformation mechanisms with strain field measurements using digital image correlation combined with orthotropic, elastic–plastic finite element model updating predictions. Random-in-plane microfibrillated lignocellulose (MFLC) composites showed better mechanical properties than WF composites due to stronger strain-hardening from lower porosity and better interfibrillar adhesion, provided by the intrinsic lignin-hemicellulose binder. Axially oriented wood fiber composites (O-WF) achieved comparable mechanical properties to random MFLC, with lower values for eco-indicators. The FEM updating method could successfully determine all 4 independent elastic constants from one 45° off-axis experiment, although the plasticity model required two more experiments.
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| 9. |
- Oliaei, Erfan, 1991-, et al.
(författare)
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Highly reinforced and degradable lignocellulose biocomposites by polymerization of new polyester oligomers
- 2022
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Unbleached wood fibers and nanofibers are environmentally friendly bio-based candidates for material production, in particular, as reinforcements in polymer matrix biocomposites due to their low density and potential as carbon sink during the materials production phase. However, producing high reinforcement content biocomposites with degradable or chemically recyclable matrices is troublesome. Here, we address this issue with a new concept for facile and scalable in-situ polymerization of polyester matrices based on functionally balanced oligomers in pre-formed lignocellulosic networks. The idea enabled us to create high reinforcement biocomposites with well-dispersed mechanically undamaged fibers or nanocellulose. These degradable biocomposites have much higher mechanical properties than analogs in the literature. Reinforcement geometry (fibers at 30 mu m or fibrils at 10-1000 nm diameter) influenced the polymerization and degradation of the polyester matrix. Overall, this work opens up new pathways toward environmentally benign materials in the context of a circular bioeconomy. Cellulose biocomposites from nanocellulose or plant fibers with polymer matrix are often not degradable and suffer from insufficient mechanical properties to replace established materials. Here, the authors demonstrate the fabrication of hydrolytically degradable polymers through in-situ polymerization of new functionally balanced oligomers within high-content lignocellulose reinforcement networks.
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| 10. |
- Oliaei, Erfan, 1991-
(författare)
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Lignocellulose Biocomposites– A Comparison of Wood Fibers and Microfibrillated Lignocellulose
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- All-lignocellulose composites, meaning densified fiber or fibril materials without added binder, show interesting mechanical properties and can be eco-friendly. Composites based on hot-pressed microfibrillated lignocellulose (MFLC) and lignocellulosic wood fiber (WF) reinforcements are compared with respect to processing, structure, mechanical properties, and eco-indicators. Also, these reinforcements are compared in hot-pressed degradable lignocellulosic crosslinked polycaprolactone (c-PCL) biocomposites based on in-situ polymerization of new caprolactone oligomers.The intermediate lignin content (≈11%) was favorable for MFLC preparation, although the cumulative energy demand was high for mechanical disintegration from unbleached softwood kraft pulp. The mechanical properties were much better for random-in-plane MFLC compared with WF composites due to lower porosity, better interfiber bonding, and smaller-scale defects. Data for strain-field development during tensile tests was in support of these findings. For c-PCL biocomposites, much higher ultimate strength was obtained for the c-PCL/MFLC composites compared with c-PCL/WF. The most important reason was the strainhardening behavior combined with higher strain to failure, since the scale of developing defects was much smaller with MFLC reinforcement.
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| 11. |
- Oliaei, Erfan, et al.
(författare)
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Microfibrillated lignocellulose (MFLC) and nanopaper films from unbleached kraft softwood pulp
- 2019
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Ingår i: Cellulose. - : Springer. - 0969-0239 .- 1572-882X.
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Tidskriftsartikel (refereegranskat)abstract
- Microfibrillated cellulose (MFC) is an important industrial nanocellulose product and material component. New MFC grades can widen the materials property range and improve product tailoring. Microfibrillated lignocellulose (MFLC) is investigated, with the hypothesis that there is an optimum in lignin content of unbleached wood pulp fibre with respect to nanofibril yield. A series of kraft fibres with falling Kappa numbers (lower lignin content) was prepared. Fibres were beaten and fibrillated into MFLC by high-pressure microfluidization. Nano-sized fractions of fibrils were separated using centrifugation. Lignin content and carbohydrate analysis, total charge, FE-SEM, TEM microscopy and suspension rheology characterization were carried out. Fibres with Kappa number 65 (11% lignin) combined high lignin content with ease of fibrillation. This confirms an optimum in nanofibril yield as a function of lignin content, and mechanisms are discussed. MFLC from these fibres contained a 40–60 wt% fraction of nano-sized fibrils with widths in the range of 2.5–70 nm. Despite the large size distribution, data for modulus and tensile strength of MFLC films with 11% lignin were as high as 14 GPa and 240 MPa. MFLC films showed improved water contact angle of 84–88°, compared to neat MFC films (< 50°). All MFLC films showed substantial optical transmittance, and the fraction of haze scattering strongly correlated with defect content in the form of coarse fibrils. Graphic abstract: [Figure not available: see fulltext.]
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| 12. |
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| 13. |
- Oliaei, Erfan, et al.
(författare)
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Sustainable development of hot-pressed all-lignocellulose composites—comparing wood fibers and nanofibers
- 2021
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 13:16
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Forskningsöversikt (refereegranskat)abstract
- Low-porosity materials based on hot-pressed wood fibers or nanocellulose fibrils (no polymer matrix) represent a new concept for eco-friendly materials with interesting mechanical properties. For the replacement of fossil-based materials, physical properties of wood fiber materials need to be improved. In addition, the carbon footprint and cumulative energy required to produce the material also needs to be reduced compared with fossil-based composites, e.g., glass fiber composites. Lignin-containing fibers and nanofibers are of high yield and special interest for development of more sustainable materials technologies. The present mini-review provides a short analysis of the potential. Different extraction routes of lignin-containing wood fibers are discussed, different processing methods, and the properties of resulting fiber materials. Comparisons are made with analogous lignin-containing nanofiber materials, where mechanical properties and eco-indicators are emphasized. Higher lignin content may promote eco-friendly attributes and improve interfiber or interfibril bonding in fiber materials, for improved mechanical performance.
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| 14. |
- Seddiqi, H., et al.
(författare)
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Cellulose and its derivatives : towards biomedical applications
- 2021
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Ingår i: Cellulose. - : Springer Science and Business Media B.V.. - 0969-0239 .- 1572-882X. ; 28, s. 1893-1931
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose is the most abundant polysaccharide on Earth. It can be obtained from a vast number of sources, e.g. cell walls of wood and plants, some species of bacteria, and algae, as well as tunicates, which are the only known cellulose-containing animals. This inherent abundance naturally paves the way for discovering new applications for this versatile material. This review provides an extensive survey on cellulose and its derivatives, their structural and biochemical properties, with an overview of applications in tissue engineering, wound dressing, and drug delivery systems. Based on the available means of selecting the physical features, dimensions, and shapes, cellulose exists in the morphological forms of fiber, microfibril/nanofibril, and micro/nanocrystalline cellulose. These different cellulosic particle types arise due to the inherent diversity among the source of organic materials or due to the specific conditions of biosynthesis and processing that determine the consequent geometry and dimension of cellulosic particles. These different cellulosic particles, as building blocks, produce materials of different microstructures and properties, which are needed for numerous biomedical applications. Despite having great potential for applications in various fields, the extensive use of cellulose has been mainly limited to industrial use, with less early interest towards the biomedical field. Therefore, this review highlights recent developments in the preparation methods of cellulose and its derivatives that create novel properties benefiting appropriate biomedical applications. © 2021, The Author(s).
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