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| 2. |
- Colic, Miodrag, et al.
(author)
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Cytocompatibility and immunomodulatory properties of wood based nanofibrillated cellulose
- 2015
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 22:1, s. 763-778
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Journal article (peer-reviewed)abstract
- Cellulose nanofibrils (CNFs), unique and promising natural materials have gained significant attention recently for biomedical applications, due to their special biomechanical characteristics, surface chemistry, good biocompatibility and low toxicity. However, their long bio-persistence within organisms may provoke chronic immune reactions and this aspect of CNFs has not been studied to date. Therefore, the aim of this work was to examine and compare the biocompatibility and immunomodulatory properties of CNFs in vitro. CNFs (diameters of 10-70nm; lengths of a few microns) were prepared from Norway spruce (Picea abies) by mechanical fibrillation and high pressure homogenisation. L929 cells, rat thymocytes or human peripheral blood mononuclear cells (PBMNCs) were cultivated with CNFs. None of the six concentrations of CNFs (31.25µg/ml – 1mg/ml) induced cytotoxicity and oxidative stress in the L929 cells, nor induced necrosis and apoptosis of the thymocytes and PBMNCs. Higher concentrations (250µg/ml – 1mg/ml) slightly inhibited the metabolic activities of the L929 cells as a consequence of inhibited proliferation. The same concentrations of CNFs suppressed the proliferation of PBMNCs to phytohemaglutinine, a T-cell mitogen, and the process was followed by down-regulation of interleukin-2 (IL-2) and interferon-γ (IFN-γ) production. The highest concentration of CNFs inhibited IL-17A but increased IL-10 and IL-6 production. The secretions of the inflammatory cytokines, IL-1β and the tumor necrosis factor-α (TNF-α) as well as Th2 cytokine (IL-4), remained unaltered. In conclusion, the results suggest that these CNFs are biocompatible, non-inflammatory and non-immunogenic nanomaterial. Higher concentrations seem to be tollerogenic to the immune system, a characteristic very desirable for implantable biomaterials.
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| 3. |
- Goetz, Lee, et al.
(author)
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All cellulose electrospun water purification membranes nanotextured using cellulose nanocrystals
- 2018
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 25:5, s. 3011-3023
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Journal article (peer-reviewed)abstract
- Cellulose acetate (CA) fibers were electrospun on a mesh template to create specific surface and pore structures for membrane applications. The mesh template CA fiber mats were impregnated with cellulose nanocrystals at varying weight percentages. The membranes showed nanotextured surfaces and improved mechanical properties post impregnation. More importantly, the hydrophilicity of the original CA fibers was increased from a hydrophobic contact angle of 102 degrees-0 degrees thereby creating an anti-fouling membrane surface structure. The membranes showed rejection of 20-56% for particles of 0.5-2.0 mu m, indicating potential of these membranes in rejecting microorganisms from water. Furthermore, high rejection of dyes (80-99%) by adsorption and potential application as highly functional affinity membranes was demonstrated. These membranes can therefore be utilized as all-cellulose, green, scalable and low cost high flux membranes (> 20,000 LMH) for water cleaning applications in food industry where microorganisms and charged contaminants are to be removed.
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| 4. |
- Mathew, Aji P., et al.
(author)
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Process scale up and characterization of wood cellulose nanocrystals hydrolysed using bioethanol pilot plant
- 2014
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In: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 58, s. 212-219
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Journal article (peer-reviewed)abstract
- The paper discusses the isolation of cellulose nanocrystals (CNCBE) from wood resources by integrating the processing with pilot-scale bioethanol processing unit. The nanocrystals were isolated from cellulose obtained by acid pretreatment of wood chips in a bioethanol pilot-scale facility, followed by a series of chemical processes and subsequent homogenization using a lab-scale homogenizer. The isolated nanocrystals had diameters of 5-15 nm, cellulose I crystalline structure and formed a thick semi-transparent gel at low concentration (2 wt%). XPS data showed that these nanocrystals had predominantly O=C-O surface groups which also contributed to its high negative zeta potential. Casted CNCBE films showed excellent mechanical performance (200 MPa of strength, 16 GPa of modulus) and transparency and were also found to be cytocompatible. The developed process route resulted in high-quality nanocellulose crystals with a yield of 600 g/day.
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| 5. |
- Naseri, Narges, et al.
(author)
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3-Dimensional Porous Nanocomposite Scaffolds Based on Cellulose Nanofibers for Cartilage Tissue Engineering
- 2016
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:8, s. 5999-6007
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Journal article (peer-reviewed)abstract
- Fully bio-based three-dimensional porous scaffold for cartilage repair was prepared via freeze-drying where cellulose nanofibers, which were cytocompatible, were used as mechanical reinforcement (70-90 wt%) in a matrix of gelatin and chitosan (9:1) and crosslinked using genipin. Morphology studies showed that the scaffolds had interconnected pores with favorable pore diameters (< 250 μm) for cell growth. Compression modulus of the scaffolds (1-3 MPa) at room conditions was in the range for natural cartilage and decreased significantly (0.03-0.05 MPa) in phosphate buffered saline (PBS) at 37°C. The high PBS uptake shown by the scaffolds (< 3000 wt%) was attributed to liquid trapped in the pores during immersion in PBS. Furthermore, the scaffolds showed good cytocompatibility towards chondrocytes, which attached and proliferated properly. The scaffolds are considered to have potential in cartilage tissue engineering due to high porosity (≈ 95%) and good mechanical performance that promote cell attachment and extracellular matrix (ECM) production.
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| 6. |
- Naseri, Narges, et al.
(author)
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3-Dimensional porous nanocomposite scaffolds based on cellulose nanofibers for cartilage tissue engineering : tailoring of porosity and mechanical performance
- 2016
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:8, s. 5999-6007
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Journal article (peer-reviewed)abstract
- Fully bio-based 3-dimensional porous scaffolds based on freeze-dried cellulose nanofibers (70-90 wt%) stabilized using a genipin crosslinked matrix of gelatin and chitosan were prepared. Morphology studies using scanning electron microscopy showed that the scaffolds have interconnected pores with average pore diameters of 75-200 mu m and nanoscaled pore wall roughness, both favorable for cell interactions with cartilage repair. X-ray tomography confirmed the 3-dimensional homogeneity and interconnectivity of the pores as well as the fibrillar structure of the scaffolds. The compression modulus of the scaffolds (1-3 MPa) at room conditions was higher than natural cartilage (approximate to 1 MPa). The lowered compression modulus of 10-60 kPa in phosphate buffered saline (PBS) at 37 degrees C was considered favorable for chondrogenesis. The current study therefore successfully addressed the challenge of tailoring the pore structure and mechanical properties simultaneously for cartilage regeneration. Furthermore, the scaffolds' high porosity (approximate to 95%), high PBS uptake and good cytocompatibility towards chondrocytes are considered beneficial for cell attachment and extracellular matrix (ECM) production.
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| 7. |
- Naseri, Narges, et al.
(author)
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Electrospinnability of bionanocomposites with high nanocrystal loadings : The effect of nanocrystal surface characteristics
- 2016
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 147, s. 464-472
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Journal article (peer-reviewed)abstract
- This paper deals with the effect of solution properties and nanoparticle surface chemistry on the spinnability of a chitosan/polyethylene oxide (PEO) with high concentration (50 wt%) of chitin and cellulose nanocrystals and the properties of the resultant nanocomposite fibers/fiber mats. Electrospinning dispersions with cellulose nanocrystals having sulphate surface groups showed poor spinnability compared to chitin nanocrystals with amide and amino groups. Chitin nanocrystal based dispersions showed good spinnability and continuous fiber formation whereas cellulose nanocrystal system showed discontinuous fibers and branching. The viscosity and surface tension are shown to impact this behavior, but conductivity did not. Poor spinnability observed for cellulose nanocrystal based fibers was attributed to the coagulation of negatively charged cellulose nanocrystals and positively charged chitosan. The study showed that the nanocrystal surface charge and interactions with the chitosan/PEO matrix have a significant impact on the spinnability of bionanocomposites.
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| 8. |
- Naseri, Narges, et al.
(author)
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Electrospun chitosan-based nanocomposite mats reinforced with chitin nanocrystals for wound dressing
- 2014
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 109, s. 7-15
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Journal article (peer-reviewed)abstract
- The aim of this study was to develop electrospun chitosan/polyethylene oxide- based randomly oriented fiber mats reinforced with chitin nanocrystals (ChNC) for wound dressing. Microscopy studies showed porous mats of smooth and beadless fibers with diameters between 223-966 nm. The addition of chitin nanocrystals as well as crosslinking had a positive impact on the mechanical properties of the mats, and the crosslinked nanocomposite mats with a tensile strength of 64.9 MPa and modulus of 10.2 GPa were considered the best candidate for wound dressing application. The high surface area of the mats (35 m2.g−1) was also considered beneficial for wound healing. The water vapor transmission rate of the prepared mats was between 1290-1548 g.m−2.day−1, and was in the range for injured skin or wounds. The electrospun fiber mats showed compatibility towards adipose derived stem cells, further confirming their potential use as wound dressing materials.
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| 9. |
- Naseri, Narges, et al.
(author)
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Electrospun chitosan nanofiber random mats reinforced with cellulose nanowhiskers : Poster Presentation
- 2013
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Conference paper (peer-reviewed)abstract
- Chitosan is a non-toxic, antibacterial, biodegradable and biocompatible biopolymer used extensively for biomedical applications such as tissue engineering, drug and gene delivery, wound healing etc. Electrospinning of chitosan solution in acetic acid (50%) was carried out at 25 kV, gap distance of 155 mm, flow rate 13 mL/h. Cellulose nanowhiskers having diameters of 5-10 nm and aspect ratio of ≈150, were isolated from microcrystalline cellulose (MCC) and used as the reinforcement in the electrospun random mats. The mats were further crosslinked using genipin to improve mechanical properties. The electrospun fibers had diameters in the range of 130-300 nm. With inclusion of the whiskers decreased 50% of average fiber diameters. The mechanical properties of electrospun mats increased as a function of nanowhisker addition as well as crosslinking. These electrospun mats are expected to find application in wound dressing, burn healing etc.
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| 10. |
- Naseri, Narges, et al.
(author)
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Electrospun chitosan nanofiber random mats reinforced with chitin and cellulose nanocrystals for wound dressing application
- 2013
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Conference paper (peer-reviewed)abstract
- IntroductionProcessingof ultrafine continuous polymeric fibers ranging from tensof nanometers to a few micrometers using electtrospinning techniqueis well known1. In recent years, nanosized reinforcements have been usedto further improve/ tailor the mechanical properties and structural morphologyof electrospun fibers2. The current study is aimed to developrandomly oriented nanocomposite fiber mats by electrospinning,using cellulose and chitin nanocrystals as reinforcements3/ functionaladditives and explore the potential of the electrospun nanofiber mats for wounddressing application.Materials and methodsElectrospinning of chitosan solution in aceticacid (50%) was carried out at 25 kV, gap distance of 155mm, flow rate13 mL/h. Cellulose nanocrystal (CNCs) having diameters of5-10 nm were isolated from microcrystalline cellulose (MCC) by63% sulphuric acid hydrolysis using Bondeson et alprocedure3.Chitin nanocrystals (ChNCs) were produced from crab shells by HClhydrolysis. The concentrations of nanocrystals in all themats were kept at 50%. The spinning solution used was a mixture of1:1 (w/w) of chitosan-PEO in 50 wt% aqueous acetic acid, with a3 wt% total polymer concentration. The mats werefurther crosslinked using genipin in order to improvemechanical properties.Results and discussionCNCs and ChNCs werefound to be biocompatible and supported growth of adiposederived stem cells (ASC) and L929 cell line indicating thatthese nanomaterials are potential reinforcements/ functional additivesfor biomedical products. Randomly oriented nanofiber mats wereprepared and the effect of inclusion of CNCs and ChNCs on the structuralmorphology and diameter of electrospun nanofiber werestudied. Crosslinking of the mats resulted in more compact film likestructure for only matrix (M) and M-CNCH2SO4 while M-ChNC and MCNCHCLmats wereless affected. The electrospun fibers had diameters in the range of116-631 nm, which decreasedwith inclusion of nanocrystals except for M-CNCH2SO4 whereaggregation of CNCs probably occurred. The nanocrystals as well asthe crosslinking had positive impact on the mechanicalproperties of electrospun mats. The random mats showed porosity andare expected to facilitate cell growth, though porosity decreasedwith crosslinking probably due to dissolution of PEO. The matsexhibited water vapour permeability in the range of 1202-1879 g.m2day-1, which falls in the range of water vapour transmissionfor wounds and the permeability decreased slightlyafter crosslinking. ConclusionsRandomlyoriented nanofiber electrospun mats were successfully producedfrom chitosan/ PEO blend reinforced with CNCs orChNCs. Electrospun porous random mats reinforced withChNCs are the most promising materials (fibers free of defects).The crosslinking had positive impact on mechanicalstrength where as porosity and water vapour transmissiondecreased after crosslinking. The porous morphology of the matsfacilitated cell growth and water vapour transmission and is expectedto have potential application as wound healing materials. Acknowledgments Financial support fromVINNOVA (No. 2011-02071) under MNT-ERANET project, n-POSSCOG isacknowledged. EDUCELL, Slovenia and CSIR, S. Africa are acknowledgedfor biocomatibility studies and water vapour transmissionstudies respectievely. References1. Son, W.K.; Youk,J.H. et al . J. Poly Sci. , 2004, 42 (1), 5-11.2. Oksman, K.;Mathew, A.P.; Sain, M., Plastics, Rubber &Composites, 2009, 38, 396-405.3. Bondeson, D.;Mathew, A. P.; Oksman, K. Cellulose, 2006,13, 171- 180. Proceeding of the MiMeOctober 8-11, 2013 - Faenza, Italy1st InternationalConference on Materials in Medicine
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