| 1. |
- Basu, Alex, et al.
(författare)
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On the use of ion-crosslinked nanocellulose hydrogels for wound healing solutions : Physicochemical properties and application-oriented biocompatibility studies
- 2017
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 174, s. 299-308
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Tidskriftsartikel (refereegranskat)abstract
- Calcium ion-crosslinked nanofibrillated cellulose (NFC) hydrogels were investigated as potential materials for wound healing dressings. The physicochemical properties of the hydrogels were examined by rheology and water retention tests. Skin cells and monocytes were selected for application-oriented bio-compatibility studies. The NFC hydrogels presented entangled fibrous networks and solid-like behavior. Water retention tests showed the material's potential to maintain a suitable moist environment for different type of wounds. The hydrogels did not affect dermal fibroblasts monolayer cultures upon directcontact, as cell monolayers remained intact after application, incubation and removal of the materials. Inflammatory response studies with blood-derived mononuclear cells revealed the inert nature of the hydrogels in terms of cytokine secretion and reactive oxygen species production. Results highlight the great potential of ion-crosslinked NFC hydrogels for the development of advanced wound dressings, where further functionalization of the material could lead to improved properties towards the healing of specific wound types.
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| 2. |
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| 3. |
- Blasi-Romero, Anna, et al.
(författare)
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In Vitro Investigation of Thiol-Functionalized Cellulose Nanofibrils as a Chronic Wound Environment Modulator
- 2021
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- There is currently a huge need for new, improved therapeutic approaches for the treatment of chronic wounds. One promising strategy is to develop wound dressings capable of modulating the chronic wound environment (e.g., by controlling the high levels of reactive oxygen species (ROS) and proteases). Here, we selected the thiol-containing amino acid cysteine to endow wood-derived cellulose nanofibrils (CNF) with bioactivity toward the modulation of ROS levels and protease activity. Cysteine was covalently incorporated into CNF and the functionalized material, herein referred as cys-CNF, was characterized in terms of chemical structure, degree of substitution, radical scavenging capacity, and inhibition of protease activity. The stability of the thiol groups was evaluated over time, and an in vitro cytotoxicity study with human dermal fibroblasts was performed to evaluate the safety profile of cys-CNF. Results showed that cys-CNF was able to efficiently control the activity of the metalloprotease collagenase and to inhibit the free radical DPPH (1,1-Diphenyl-2-picrylhydrazyl radical), activities that were correlated with the presence of free thiol groups on the nanofibers. The stability study showed that the reactivity of the thiol groups challenged the bioactivity over time. Nevertheless, preparing the material as an aerogel and storing it in an inert atmosphere were shown to be valid approaches to increase the stability of the thiol groups in cys-CNF. No signs of toxicity were observed on the dermal fibroblasts when exposed to cys-CNF (concentration range 0.1-0.5 mg/mL). The present work highlights cys-CNF as a promising novel material for the development of bioactive wound dressings for the treatment of chronic wounds.
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| 4. |
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| 5. |
- Changqing, Ruan, et al.
(författare)
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A green and simple method for preparation of an efficient palladium adsorbent based on cysteine functionalized2,3-dialdehyde cellulose
- 2016
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 23:4, s. 2627-2638
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Tidskriftsartikel (refereegranskat)abstract
- A green and efficient adsorbent for adsorption of palladium ions was prepared from 2,3-dialdehyde cellulose (DAC) originating from nanocellulose from the green algae Cladophora. The DAC was functionalized with cysteine via reductive amination in a convenient one-pot procedure to provide the adsorbent. The adsorption properties for adsorbing palladium(II) ions, including capacity, adsorption isotherm and kinetics, were studied. The successful reductive amination of cysteine with 2,3-dialdehyde cellulose was confirmed by FT-IR, elemental analysis and XPS. The adsorbent was characterized by SEM, XRD, gas adsorption and TGA. The adsorbent had a high adsorption capacity (130 mg palladium per gram adsorbent) and enabled fast adsorption of palladium(II) ions from solution (80 % of maximum capacity reached in 2 h). Adsorbent materials suitable for both filters (fibrous) and column matrixes (spherical particles) could be obtained in an efficient manner by controlling the degree of oxidation while producing the DAC material.
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| 6. |
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| 7. |
- Frasca, Serena, et al.
(författare)
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Toward Biomass-Based Organic Electronics : Continuous Flow Synthesis and Electropolymerization of N-Substituted Pyrroles
- 2024
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 9:12, s. 13852-13859
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Tidskriftsartikel (refereegranskat)abstract
- Pyrroles are foundational building blocks in a wide array of disciplines, including chemistry, pharmaceuticals, and materials science. Currently sourced from nonrenewable fossil sources, there is a strive to explore alternative and sustainable synthetic pathways to pyrroles utilizing renewable feedstocks. The utilization of biomass resources presents a compelling solution, particularly given that several key bulk and fine chemicals already originate from biomass. For instance, 2,5-dimethoxytetrahydrofuran and aniline are promising candidates for biomass-based chemical production. In this study, we present an innovative approach for synthesizing N-substituted pyrroles by modifying the Clauson-Kaas protocol, starting from 2,5-dimethoxytetrahydrofuran as the precursor. The developed methodology offers the advantage of producing pyrroles under mild reaction conditions with the potential for catalyst-free reactions depending upon the structural features of the substrate. We devised protocols suitable for both continuous flow and batch reactions, enabling the conversion of a wide range of anilines and sulfonamides into their respective N-substituted pyrroles with good to excellent yields. Moreover, we demonstrate the feasibility of depositing thin films of the corresponding polymers onto electrodes through in situ electropolymerization. This innovative application showcases the potential for sustainable, biomass-based organic electronics, thus, paving the way for environmentally friendly advancements in this field.
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| 8. |
- Frasca, Serena, et al.
(författare)
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Toward biomass-based organic electronics: Continuous flow synthesis and electropolymerization of N-substituted polypyrroles
- 2023
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Ingår i: ACS Spring meeting 2023. - Indianapolis.
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Konferensbidrag (refereegranskat)abstract
- Pyrroles are important building blocks in many areas of chemistry, pharmaceuticals and materials. Pyrroles are currently fossil-based and transition to renewable alternatives demands new synthetic pathways. The use of biomass is a very attractive option for more sustainable solutions and several bulk and fine chemical are already produced from biomass. 2,5-Dimethoxytetrahydrofuran is an example of fine chemical derived from carbohydrate fraction of biomass. Here we report the synthesis of N-substituted pyrroles through a modified Clauson-Kass protocol starting from 2,5-dimethoxytetrahydrofuran. The proposed method allows to obtain pyrroles under mild reaction conditions and it can be performed catalyst-free. The protocol works both in continuous flow and under batch conditions.. A wide range of anilines and sulphonamides are transformed to corresponding N-substituted pyrroles in good to excellent yields. Conductive films are achieved through electropolymerization and they show distinct redox activity. Current efforts entail the application of the material in sensors or energy storage devices. The proposed method opens the pathway to sustainable biomass-based organic electronics.
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| 9. |
- Han, Yilin, et al.
(författare)
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Towards 3D Bioprinted Spinal Cord Organoids
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 23:10
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional (3D) cultures, so-called organoids, have emerged as an attractive tool for disease modeling and therapeutic innovations. Here, we aim to determine if boundary cap neural crest stem cells (BC) can survive and differentiate in gelatin-based 3D bioprinted bioink scaffolds in order to establish an enabling technology for the fabrication of spinal cord organoids on a chip. BC previously demonstrated the ability to support survival and differentiation of co-implanted or co-cultured cells and supported motor neuron survival in excitotoxically challenged spinal cord slice cultures. We tested different combinations of bioink and cross-linked material, analyzed the survival of BC on the surface and inside the scaffolds, and then tested if human iPSC-derived neural cells (motor neuron precursors and astrocytes) can be printed with the same protocol, which was developed for BC. We showed that this protocol is applicable for human cells. Neural differentiation was more prominent in the peripheral compared to central parts of the printed construct, presumably because of easier access to differentiation-promoting factors in the medium. These findings show that the gelatin-based and enzymatically cross-linked hydrogel is a suitable bioink for building a multicellular, bioprinted spinal cord organoid, but that further measures are still required to achieve uniform neural differentiation.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Katsiotis, Christos S.
(författare)
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Additive Manufacturing and Mesoporous Materials for Pharmaceutical Applications
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Additive Manufacturing (AM), over the past decade, has evolved into a versatile technology with significant applications in pharmaceutical research. This technology enables the production of drug formulations tailored to individual patients, offering customization in both dosage and dissolution profiles. While challenges in mass production persist, 3D printing, particularly through techniques like Fused Deposition Modeling (FDM) and Semi Solid Extrusion (SSE), proves ideal for crafting smaller batches of personalized dosage forms.A prevalent issue in drug development revolves around poor water solubility, impacting bioavailability upon oral administration. To combat this, the integration of mesoporous materials emerges as a promising strategy to enhance the dissolution of poorly water-soluble drugs. Here, the applicability of mesoporous materials is explored, as well as their incorporation with various AM techniques. Overall, the thesis dives into the investigation of combinatorial formulations, incorporating at least one 3D printed component to address specific requirements in drug delivery. By combining FDM with Selective Laser Sintering (SLS), a hybrid two-compartmental formulation is developed. The durable FDM-printed shell regulates buffer medium access to the contained SLS-produced inserts loaded with the drug. Varying printing parameters and insert combinations within the shell showcase the adjustability and flexibility of this hybrid approach.Tablets with different infill percentages, containing drug-loaded mesoporous materials, are developed. Poorly water-soluble drugs are successfully amorphized within mesoporous material pores, formulated into filaments through Hot Melt Extrusion (HME), and printed via FDM. These tablets exhibit improved dissolution compared to the crystalline drug, with the dissolution behavior regulated also by the infill percentage.The study explores the impact of drug-loaded mesoporous materials on HME-produced filament properties, studying their effect on maximum tensile strength and Young’s modulus. The relationship between these properties and filament printability is investigated. Additionally, a protective effect of mesoporous materials on drugs from thermal degradation is revealed.For Semi Solid Extrusion (SSE) manufactured formulations, a paste is developed, comprising mesoporous material loaded with a poorly water-soluble drug and an excipient. This paste demonstrates favorable rheological properties and easy extrudability via a syringe. The formulation proves versatile for printing dosage forms for both oral and rectal administration, with the printed tablet and suppository exhibiting effective drug release.In conclusion, this work presents valuable strategies for developing patient-tailored dosage forms, addressing specific pharmaceutical challenges like poor solubility. The integration of mesoporous materials and various 3D printing techniques showcases a promising direction for personalized medicine in the pharmaceutical field.
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| 15. |
- Katsiotis, Christos S., et al.
(författare)
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Combinatorial 3D printed dosage forms for a two-step and controlled drug release
- 2023
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 187
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Tidskriftsartikel (refereegranskat)abstract
- Fused deposition modeling (FDM) and selective laser sintering (SLS) are two of the most employed additive manufacturing (AM) techniques within the pharmaceutical research field. Despite the numerous advantages of different AM methods, their respective drawbacks have yet to be fully addressed, and therefore combinatorial systems are starting to emerge. In the present study, hybrid systems comprising SLS inserts and a two-compartment FDM shell are developed to achieve controlled release of the model drug theophylline. Via the use of SLS a partial amorphization of the drug is demonstrated, which can be advantageous in the case of poorly soluble drugs, and it is shown that sintering parameters can regulate the dosage and release kinetics of the drug from the inserts. Furthermore, via different combinations of inserts within the FDM-printed shell, various drug release patterns, such as a two-step or prolonged release, can be achieved. The study serves as a proof of concept, highlighting the advantages of combining two AM techniques, both to overcome their respective shortcomings and to develop modular and highly tunable drug delivery devices.
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| 16. |
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| 17. |
- Levine, Valerie, 1996-, et al.
(författare)
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Geometry impact on fundamental properties of theophylline-containing SLS printed pharmaceutical tablets
- 2024
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Ingår i: Frontiers in Drug Delivery. - 2674-0850. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Selective Laser Sintering (SLS) has the potential to offer a more accurate alternative to current-practice manipulation of oral dosage forms for pediatric, geriatric, and dysphagia-suffering patient groups. In order to create the best possible dosage forms for these patient groups, an in-depth look into how a dosage forms geometry impacts the overall properties is essential. In this study, the impact of geometry on SLS manufactured oral dosage forms on the tablet’s microstructure, actual-to-theoretical volume, mass deviation, disintegration, and dissolution was investigated. Three different shapes; cylinder, hollow cylinder, and conical frustum with similar surface area (SA), as well as three cylinders with different diameters, were investigated. The results indicate that the geometry has an impact on the mass uniformity, resultant volume, disintegration, and dissolution properties of the tablets. The mass uniformity analysis of the tablets provided the most variation between tablets of different sizes, with more uniformity for tablets with similar SA-to-volume ratio (SA/V). When examining the actual-to-theoretical volume of the tablets, a greater variance between the actual and theoretical volumes for shapes with higher overall SA was observed. The values found are approximately 1.05 for the three differently sized cylinders, 1.23 for the conical frustum, and 1.44 for the hollow cylinder, following this trend. Disintegration data supported a link between SA/V and average disintegration time, observed with the tablet of the highest SA/V disintegrating in 12 s and the tablet with the lowest SA/V disintegrating in 58 s. Dissolution results also indicated a strong dependence on SA/V. Hence, when novel ways to produce oral dosage form tablets become available by additive manufacturing, such as SLS, both geometry and SA/V must be taken into consideration in the tablet design process to ensure appropriate release kinetics and dosing standards.
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| 18. |
- Levine, Valerie R., 1996-, et al.
(författare)
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Geometry Study of Theophylline-Containing SLS Printed Pharmaceutical Tablets
- 2022
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Konferensbidrag (refereegranskat)abstract
- Purpose: There are many challenges in the pharmaceutical industry with modifications to oral dosage forms. This is especially apparent for certain demographics, including pediatric and geriatric patients. With regards to oral dosage forms for children, fixed-dose tablets designed for adults are used and require manual manipulation. This is often due to the lack of available premade dosages in the right strength. (Kader et al., 2021) For some groups, such as pediatric oncology patients, as many as 74% need manipulation of dosage forms. (Johannesson et al., 2022) The common practice for manipulation of oral dosage forms is to cut the tablets with a knife or pill cutter, which is of low accuracy and high patient and caregiver risk. A solution to this problem would be to create customizable additive manufactured oral dosage forms. Pharmaceutical tablets created with additive manufacturing technologies are developing in many print styles, including powder printing. While technologies like Fused Deposition Modelling (FDM) have come to a level of maturation for their own specific applications in pharmaceutical printing, Selective Laser Sintering (SLS) is still developing for pharmaceutical applications. This style of printing allows for a variable shape and an aesthetic similar to a traditionally pressed tablet. Many of the features of these printed tablets, however, are still unknown, as this technology is still rather new. The impact of the geometry of the tablets is one such area that is still not sufficiently explored, which is an essential analysis for the path to adoption of this technology for pharmaceutical application. Employing SLS technology, surface area and surface area to volume ratio impacts were analyzed to determine the effects of these variables.Methods: For this study, theophylline was used as the API (active pharmaceutical ingredient), Kollidon VA 64 was used as the polymer, Aerosil was used as the excipient, and activated carbon was used as the colorant. The composition of the powder material used for printing was 10% API (theophylline), 88.5% polymer (Kollidon VA 64), 0.5% excipient (Aerosil), and 1% colorant (activated carbon). For the comparison of the impact of surface area on tablets, three different shapes were chosen as a comparison: a cylinder, a hollow cylinder, and a conical frustum. Dimensions of these shapes were chosen to have similar surface areas, so an impact comparison could be achieved. The basis for the surface area of the shapes was a cylinder with a height of 4 mm and a radius of 5 mm. For the comparison of surface area to volume, different size cylinders were printed, since this is the simplest shape, thus creating different surface area to volume ratios. Radii of 3 mm, 5 mm, and 7 mm were chosen for comparison (surface area to volume ratios of 1.17, 0.9, and 0.79, respectively), all with a height of 4 mm for the tablets. Fusion 360 modelling software was employed to design the tablets and a Sintratec Kit printer was used to print the tablets, all with the same print settings. After printing, characterization was done and differences between the tablets were investigated.Results: On examination of the tablet masses, a consistency of the print quality can be observed, which is a promising result for the SLS print method, since all geometries were printed with the same settings. The geometries are consistent in that the average mass deviations are within the requirement for European Pharmacopoeia standards for tablets in their weight ranges. (2.9.5. Uniformity of Mass of Single-Dose Preparations, 2020) DSC analysis showed a partial crystallinity of the tablets, while dissolution data showed clear trends.Conclusion: The geometries of tablets are important for the further development of SLS additive manufacturing technology for pharmaceutical application. Consideration into the shape, surface area, and volume are key for oral dosage forms created with this technology. An understanding of this may lead to better future application for select patient groups, such as the pediatric population.
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| 19. |
- Levine, Valerie R., 1996-, et al.
(författare)
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Investigation of Polymers for SLS 3D-Printing of Solid Oral Dosage Forms
- 2022
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Konferensbidrag (refereegranskat)abstract
- Purpose: Selective laser sintering (SLS) for oral dosage forms is a new field still in its infancy (Fina et al., 2017). This method does, however, show promise for the application of printing oral dosage forms, particularly for small-batch scenarios or for dosages in pediatric populations, where standard medications are often not suitable due to the different size and treatment requirements of children (Ivanovska et al., 2014). In addition, 3D printing technology provides a great opportunity to speed-up clinical trials and therefore shorten development timelines. SLS printing of oral dosage forms requires specific formulation design, which includes polymers often adapted for conventional pharmaceutical usage. Current commercially available polymers are often not specifically designed for SLS printing. Therefore, there is a high need to generate application data on how to optimally print these dosage forms as well as the need for dedicated polymers suitable for this application. The development of dedicated polymers with optimized properties includes the evaluation of amphiphilic PVA grades. A direct comparison of PVA 3-82, PVA 5-74 and PVA 4-88 with other commonly used polymers is presented here. This study aims to elaborate the print parameters for a host of common pharmaceutical polymers, as well as the new PVA polymers, with regards to print temperature and laser scan speed. Additionally, this study aims to follow as closely as possible to relevant Pharmacopeia standards for tablets to show the viability of SLS as a method and find print conditions for realistic oral dosage forms.Methods: For this study PVA 3-82, PVA 5-74 and PVA 4-88 (Parteck® MXP), PVP-VA(1) (Kollidon® VA 64), PVP-VA(2) (Plasdone™) were examined. These polymers were used in formulations of 88.5% polymer, 10% API (indomethacin), 0.5% flow regulation agent (silicon dioxide colloidal), and 1% colorant (silica-based pigment, Candurin® NXT Ruby Red). A tablet design was created using Fusion 360 modelling software and translated to an STL file. A Sintratec Kit printer (2.3 W diode, λ=455 nm) was utilized to print 36 tablets per each batch, each with the same overall settings (i.e. layer height of 150 µm, 3 perimeters, hatch spacing of 50 µm). For each different polymer tested, three different temperatures and three different laser scan speeds were chosen to find optimal print conditions for each formulation; 75 ℃, 100 ℃, and 125 ℃ & 200 mm/s, 300 mm/s, and 400 mm/s, respectively. Some of the polymers, however, could not withstand the 125 ℃ print temperature, so a temperature of 112.5 ℃ was chosen instead as the upper temperature limit. After completion of printing of the tablets, characterization occurred via XRD, DSC, friability testing, mass and size analysis, HPLC, as well as dissolution.Results: During printing of the tablets, it was found that the materials PVP-VA(1) and PVP-VA(2) showed signs of the material melting together in the powder bed at 125 ℃. Therefore, the temperature of upper limit for these formulations was 112.5 ℃. Upon evaluation, the most robust tablets per batch were generally printed at higher temperature (without exceeding the appropriate temperature window for each polymer) and lower laser scan speed. These tablets generally appeared better sintered together, had less signs of crystallinity with XRD and DSC analysis, and performed better in friability testing. The mass deviations for these samples also passed mass criteria of Pharmacopeia standards in several cases. Dissolution studies showed a strong solubility enhancement of PVA based formulation compared to the crystalline drug compound.Conclusion: The print ranges for these polymers commonly used in the pharmaceutical industry, as well as the newly developed PVA grades PVA 3-82 and PVA 5-74, could be individually defined based on variations in temperature and laser scan speed. Generally, trends of higher temperatures within the print range and lower laser scan speeds showed the best results upon characterization and visual inspection. These tablets were less powdery on the surface, more fitting to the desired shape of the intended tablet (i.e. less shifting between layers), and darker in color (implying a more complete sintering). The application of SLS printing in the area of solubility enhancement is a great step into further advancing the technology and allowing the development of patient-centered medication.
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| 20. |
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| 21. |
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| 22. |
- Lindh, Jonas, 1977-
(författare)
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Palladium(II)-Catalyzed Coupling Reactions
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sustainable chemical processes are becoming increasingly important in all fields of synthetic chemistry. Catalysis can play an important role in developing environmentally benign chemical processes, and transition metals have an important role to play in the area of green chemistry. In particular, palladium(II) catalysis includes many key features for successful green chemistry methods, as demonstrated by a number of eco-friendly oxidation reactions catalyzed by palladium(II). The aim of the work presented in this thesis was to develop novel and greener palladium(II)-catalyzed coupling reactions. In striving to achieve this aim, the first open-vessel, room-temperature palladium(II)-catalyzed oxidative Heck reaction, using oxygen from the air as the reoxidant of palladium, was developed. In a further investigation of the palladium(II)-catalyzed oxidative Heck reaction, base-free conditions for the transformation were identified and suitable conditions for microwave-assisted oxidative Heck reactions were established. A convenient and low-cost palladium(II)-catalyzed method for the synthesis of styrene derivatives, by coupling arylboranes with vinyl acetate, was developed. The reaction mechanism was studied using ESI-MS, which enabled the detection of cationic palladium intermediates in ongoing productive reactions, and a plausible catalytic cycle was proposed. In an attempt to make the oxidative Heck and the styrene synthesis reactions more attractive from an industrial point of view, conditions for continuous flow synthesis were identified. The results were generally good and rapid synthesis of the desired products was obtained. The first palladium(II)-catalyzed C–P bond-forming Hirao-type reaction, employing arylboranes instead of the commonly used aryl halides, was developed. An ESI-MS study was performed, and a plausible catalytic pathway was suggested. Finally, a novel method for synthesizing aryl ketones from benzoic acids and nitriles, via palladium(II)-catalyzed decarboxylation of the benzoic acids, was established. Further, the reaction mechanism was studied by ESI-MS and a plausible catalytic route presented.
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| 23. |
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| 24. |
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| 25. |
- Pan, Ruijun
(författare)
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Cladophora Cellulose-based Separators for Lithium Batteries
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of lithium-ion batteries (LIBs) has been focused on exploring and improving the electrode materials and electrolytes in the past decades. An indispensable component, the separator, is however not studied as extensively. In general, a separator has two functions, i.e. preventing the direct contact between the cathode and anode and providing the ionic transport pathways. Commercial separators for LIBs are usually made of polyolefin materials, which often have low thermal stabilities and poor electrolyte wettabilities.In this thesis, a new type of material, i.e. Cladophora cellulose, is used to manufacture separators for LIBs and lithium-metal batteries (LMBs). The separators, made with Cladophora cellulose fibers via a straightforward paper making method, possess several advantages compared to conventional polyolefin separators regarding, e.g. ionic conductivity, thermal stability, electrolyte wettability and pore distribution, providing promising alternatives for battery separators.Apart from studying the two basic functions mentioned above, two types of advanced separator functionalities have been studied, i.e. redox-activity and the attainment of a homogeneous current distribution, in conjunction with proposals for new separator designs.Two types of redox-active separators have been devised for the first time in the separator field, based on the use of a redox-active conducting polymer, polypyrrole (PPy) and a natural polymer, polydopamine (PDA). Based on their redox-active potentials, the PPy-based redox-active separator was designed to contribute capacity to the cathode of a LIB, while the PDA-based redox-active separator was proposed to be used on the anode side.It is known that a homogeneous current distribution is beneficial for the battery performance. Therefore, two new types of separators with homogenous pore distributions have been manufactured to study the influence of the pore distribution on the Li deposition/stripping behavior and composite cathode utilization in LMBs. With the knowledge obtained from the study, a stable, long lifetime paper-based LMB was designed.
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| 26. |
- Pan, Ruijun, et al.
(författare)
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Double-sided conductive separators for lithium-metal batteries
- 2019
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Ingår i: Energy Storage Materials. - : Elsevier. - 2405-8289 .- 2405-8297. ; 21, s. 464-473
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Tidskriftsartikel (refereegranskat)abstract
- A novel double-sided conductive (DSC) separator consisting of two 5 μm-thick carbon nanotube (CNT)/cellulose nanofiber (CNF) composite layers coated on each side of a 20 μm-thick glass-fiber (GF)/CNF composite membrane is described. In a lithium-metal battery (LMB), the DSC separator exhibits a high ionic conductivity (i.e. 1.7 mS cm−1 using an LP40 electrolyte) due to the high porosity (i.e. 66%) of the GF/CNF membrane. More stable Li anodes can also be realized by depositing Li within the porous electronically conducting CNT/CNF matrix at the DSC separator anode side due to the decreased current density. The CNT/CNF layer of the DSC separator facing the cathode, which is in direct electric contact with the current collector, decreases the overpotential for the cathode and consequently improves its capacity and rate performance significantly. A Li/Li cell containing a DSC separator showed an improved cycling stability compared to an analogous cell equipped with a commercial Celgard separator at current densities up to 5 mA cm−2 for Li deposition and stripping capacities up to 5 mAh cm−2. A proof-of-concept LMB containing a lithium iron phosphate (LFP) composite cathode and a DSC separator showed a significantly improved rate capability, yielding capacities of about 110 mAh g−1 at 5 C and 80 mAh g−1 at 10 C. The LMB cell containing a DSC separator also exhibited a capacity retention of 80% after 200 cycles at a rate of 6 C indicating that the two-sided conductive separator design has significant potential in facilitating the development of well-functioning LMBs.
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| 27. |
- Pan, Ruijun, et al.
(författare)
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Nanocellulose Modified Polyethylene Separators for Lithium Metal Batteries
- 2018
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Ingår i: Small. - : Wiley-VCH Verlagsgesellschaft. - 1613-6810 .- 1613-6829. ; 14:21
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Poor cycling stability and safety concerns regarding lithium (Li) metal anodes are two major issues preventing the commercialization of highâ€energy density Li metalâ€based batteries. Herein, a novel triâ€layer separator design that significantly enhances the cycling stability and safety of Li metalâ€based batteries is presented. A thin, thermally stable, flexible, and hydrophilic cellulose nanofiber layer, produced using a straightforward paperâ€making process, is directly laminated on each side of a plasmaâ€treated polyethylene (PE) separator. The 2.5 µm thick, mesoporous (≈20 nm average pore size) cellulose nanofiber layer stabilizes the Li metal anodes by generating a uniform Li+ flux toward the electrode through its homogenous nanochannels, leading to improved cycling stability. As the triâ€layer separator maintains its dimensional stability even at 200 °C when the internal PE layer is melted and blocks the ion transport through the separator, the separator also provides an effective thermal shutdown function. The present nanocelluloseâ€based triâ€layer separator design thus significantly facilitates the realization of highâ€energy density Li metalâ€based batteries.
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| 28. |
- Pan, Ruijun, et al.
(författare)
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Polydopamine-based redox-active separator for lithium-ion batteries
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of lithium-ion batteries (LIBs) can be effectively increased with functionalized separators. Herein, it is demonstrated that polydopamine-based redox-active (PRA) separators can provide additional capacity to that of typical anode materials, increase the volumetric capacity of the cell, as well as, decrease the cell resistance to yield an improved performance at higher cycling rates. The PRA separators, which are composed of a 2 µm thick electrically insulating nanocellulose fiber (NCF) layer and an 18 µm thick polydopamine (PDA) and carbon nanotube (CNT) containing redox-active layer, are readily produced using a facile paper-making process. The PRA separators are also easily wettable by commonly employed electrolytes (e.g. LP40) and exhibit a high dimensional stability even at elevated temperatures (e.g. 150 ºC). In addition, the pore structure endows the PRA separator with a high ionic conductivity (i.e. 1.06 mS cm-1 after soaking with LP40 electrolyte) that increases the rate performance of the cells. Due to the presence of the redox-active layer, Li4Ti5O12 (LTO) half-cells containing PRA separator were found to exhibit significantly higher capacities than the corresponding cells containing commercial separators. These results clearly show that the implementation of this type of redox-active separators constitutes a straightforward and effective way to increase the energy and power densities of LIBs.
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| 29. |
- Pan, Ruijun, et al.
(författare)
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Polydopamine-based redox-active separators for lithium-ion batteries
- 2019
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Ingår i: Journal of Materiomics. - : Elsevier. - 2352-8478 .- 2352-8486. ; , s. 204-213
-
Tidskriftsartikel (refereegranskat)abstract
- The performance of lithium-ion batteries (LIBs) can be effectively increased with functionalized separators. Herein, it is demonstrated that polydopamine-based redox-active (PRA) separators can provide additional capacity to that of typical anode materials, increase the volumetric capacity of the cell, as well as, decrease the cell resistance to yield an improved performance at higher cycling rates. The PRA separators, which are composed of a 2 μm thick electrically insulating nanocellulose fiber (NCF) layer and an 18 μm thick polydopamine (PDA) and carbon nanotube (CNT) containing redox-active layer, are readily produced using a facile paper-making process. The PRA separators are also easily wettable by commonly employed electrolytes (e.g. LP40) and exhibit a high dimensional stability. In addition, the pore structure endows the PRA separator with a high ionic conductivity (i.e. 1.06 mS cm−1) that increases the rate performance of the cells. Due to the presence of the redox-active layer, Li4Ti5O12 (LTO) half-cells containing PRA separator were found to exhibit significantly higher capacities than the corresponding cells containing commercial separators. These results clearly show that the implementation of this type of redox-active separators constitutes a straightforward and effective way to increase the energy and power densities of LIBs.
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| 30. |
- Pan, Ruijun, et al.
(författare)
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Sandwich-structured nano/micro fiber-based separators for lithium metal batteries
- 2019
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Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 55, s. 316-326
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Tidskriftsartikel (refereegranskat)abstract
- Although the increased need for high-energy/power-density energy storage systems has revived the research on lithium metal batteries (LMBs), the influence of the separator on the performance of LMBs is still generally neglected. In the present study, a sandwich-structured separator (referred to as the CGC separator below) composed of two 2.5µm thick cellulose nanofiber (CNF) surface layers and an intermediate 15µm thick glass microfiber (GMF) and CNF composite layer is described. While the CNF surface layers of the CGC separator feature a homogeneous distribution of nano-sized pores favoring the attainment of a homogeneous current distribution at both electrodes, the intermediate GMF/CNF layer contains macropores facilitating the ionic transport through the separator. The CGC separator exhibited a much better electrolyte wettability and thermal stability compared to a Celgard separator, due to the use of the hydrophilic and thermally stable CNFs and GMFs. It is also shown that the combination of nano-sized and micro-sized fibers used in the CGC separator yields a higher ionic conductivity than that for the commercial separator (1.14 vs. 0.49 mS cm−1). Moreover, the influence of the separator pore structure (e.g. the porosity and pore distribution) on the performance of LMBs is studied for both Li anodes and LiFePO4 composite cathodes. The results demonstrate that the use of separators with high porosities and homogeneous surface pore distributions can improve the performances (e.g. capacities and stabilities) of LMBs considerably, and also highlights the importance of proper separator/electrode interactions. The present approach constitutes a practical engineering strategy for the production of separators with nano/micro fibers and a promising route for the development of LMBs with improved safety and enhanced electrochemical performances.
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| 31. |
- Pan, Ruijun, et al.
(författare)
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Thickness difference induced pore structure variations in cellulosic separators for lithium-ion batteries
- 2017
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 24:7, s. 2903-2911
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Tidskriftsartikel (refereegranskat)abstract
- The pore structure of the separator is crucial to the performance of a lithium-battery as it affects the cell resistance. Herein, a straightforward approach to vary the pore structure of Cladophora cellulose (CC) separators is presented. It is demonstrated that the pore size and porosity of the CC separator can be increased merely by decreasing the thickness of the CC separator by using less CC in the manufacturing of the separator. As the pore size and porosity of the CC separator are increased, the mass transport through the separator is increased which decreases the electrolyte resistance in the pores of the separator. This enhances the battery performance, particularly at higher cycling rates, as is demonstrated for LiFePO4/Li half-cells. A specific capacity of around 100 mAh g-1 was hence obtained at a cycling rate of 2 C with a 10 μm thick CC separator while specific capacities of 40 and close to 0 mAh g-1 were obtained for separators with thicknesses of 20 and 40 μm, respectively. As the results also showed that a higher ionic conductivity was obtained for the 10 μm thick CC separator than for the 20 and 40 μm thick CC separators, it is clear that the different pore structure of the separators was an important factor affecting the battery performance in addition to the separator thickness. The present straightforward, yet efficient, strategy for altering the pore structure hence holds significant promise for the manufacturing of separators with improved performance, as well as for fundamental studies of the influence of the properties of the separator on the performance of lithium-ion cells.
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| 32. |
- Rezaei, Farnaz, et al.
(författare)
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Direct ink writing of high-resolution cellulose structures
- 2023
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- 3D printing is envisioned to play an important role in the production of membranes for e.g., water purification and bio-separation applications due to the prospect of creating new and cleverly designed structures. Among different 3D printing techniques, direct ink writing offers the opportunity to print a wide variety of materials with high-detail resolution. There is a range of parameters that need to be optimized in order to develop robust printing techniques at that scale. In this study, cellulose acetate (CA), which is a biocompatible material, has been used as an ink. In order to examine the printability and the possibility of printing features as small as a few mu m, nozzles with different diameters and inks with varying amounts and molecular weights of CA were investigated. Findings in this study indicate that, depending on the wetting on the underlaying structure, the nozzle's internal and external diameter affects the detail resolution of the printed structure. Different inks result in different widths of printed strands and generally a higher amount and higher molecular weights of CA results in higher detail resolution. However, too high amount of CA and molecular weight will increase the clogging risk in the nozzle. In this study, the internal size of the nozzle was 3 mu m, and by selecting a suitable ink, it was possible to print strands down to 1 mu m size and 6 mu m inter-strand distance in the air, bridging supports with limited sagging. Furthermore, wall structures consisting of 300 layers, corresponding to about 300 mu m in total height, were successfully printed.
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| 33. |
- Rocha, Igor, et al.
(författare)
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Blood Compatibility of Sulfonated Cladophora Nanocellulose Beads
- 2018
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 23:3
-
Tidskriftsartikel (refereegranskat)abstract
- Sulfonated cellulose beads were prepared by oxidation of Cladophora nanocellulose to 2,3-dialdehyde cellulose followed by sulfonation using bisulfite. The physicochemical properties of the sulfonated beads, i.e., high surface area, high degree of oxidation, spherical shape, and the possibility of tailoring the porosity, make them interesting candidates for the development of immunosorbent platforms, including their application in extracorporeal blood treatments. A desired property for materials used in such applications is blood compatibility; therefore in the present work, we investigate the hemocompatibility of the sulfonated cellulose beads using an in vitro whole blood model. Complement system activation (C3a and sC5b-9 levels), coagulation activation (thrombin-antithrombin (TAT) levels) and hemolysis were evaluated after whole blood contact with the sulfonated beads and the results were compared with the values obtained with the unmodified Cladophora nanocellulose. Results showed that neither of the cellulosic materials presented hemolytic activity. A marked decrease in TAT levels was observed after blood contact with the sulfonated beads, compared with Cladophora nanocellulose. However, the chemical modification did not promote an improvement in Cladophora nanocellulose hemocompatibility in terms of complement system activation. Even though the sulfonated beads presented a significant reduction in pro-coagulant activity compared with the unmodified material, further modification strategies need to be investigated to control the complement activation by the cellulosic materials.
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| 34. |
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| 35. |
- Rocha, Igor, et al.
(författare)
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Spectroscopic and physicochemical characterization of sulfonated Cladophora cellulose beads
- 2018
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 34:37, s. 11121-11125
-
Tidskriftsartikel (refereegranskat)abstract
- The work presents a full physicochemical characterization of sulfonated cellulose beads prepared from Cladophora nanocellulose intended for use in biological systems. 2,3-Dialdehyde cellulose (DAC) beads were sulfonated, and transformation of up to 50% of the aldehyde groups was achieved, resulting in highly charged and porous materials compared to the compact surface of the DAC beads. The porosity could be tailored by adjusting the degree of sulfonation, and a subsequent reduction of the aldehyde groups to hydroxyl groups maintained the bead structure without considerable alteration of the surface properties. The thermal stability of the DAC beads was significantly increased with the sulfonation and reduction reactions. Raman spectroscopy also showed to be a useful technique for the characterization of sulfonated cellulose materials.
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| 36. |
- Rocha, Igor, et al.
(författare)
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Sulfonated Nanocellulose Beads as Potential Immunosorbents
- 2018
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 28:3, s. 1899-1910
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Tidskriftsartikel (refereegranskat)abstract
- Herein 2,3-dialdehyde cellulose beads prepared from Cladophora green algae nanocellulose were sulfonated and characterized by FTIR, conductometric titration, elemental analysis, SEM, ζ-potential, nitrogen adsorption–desorption and laser diffraction, aiming for its application as a potential immunosorbent material. Porous beads were prepared at mild reaction conditions in water and were chemically modified by sulfonation and reduction. The obtained 15 µm sized sulfonated beads were found to be highly charged and to have a high surface area of ~ 100 m2 g−1 and pore sizes between 20 and 60 nm, adequate for usage as immunosorbents. After reduction of remaining aldehyde groups, the beads could be classified as non-cytotoxic in indirect toxicity studies with human dermal fibroblasts as a first screening of their biocompatibility. The observed properties make the sulfonated cellulose beads interesting for further development as matrix material in immunosorbent devices.
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| 37. |
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| 38. |
- Ruan, Changqing, et al.
(författare)
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Carbonized cellulose beads for efficient capacitive energy storage
- 2018
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 25:6, s. 3545-3556
-
Tidskriftsartikel (refereegranskat)abstract
- Natural biomaterials, including polysaccharides and amino acids, provide a sustainable source of functional carbon materials for electric energy storage applications. We present a one-pot reductive amination process to functionalize 2,3-dialdehyde cellulose (DAC) beads with chitosan and l-cysteine to provide single (N)- and dual (N/S)-doped materials. The functionalization enables the physicochemical properties of the materials to be tailored and can provide carbon precursors with heteroatom doping suitable for energy storage applications. Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis were used to characterize the changes to the beads after functionalization and carbonization. The results of X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy verified that the doping was effective, while the nitrogen sorption isotherms and pore-size distributions of the carbonized beads showed the effects of doping with different hierarchical porosities. In the electrochemical experiments, three kinds of carbon beads [pyrolyzed from DAC, chitosan-crosslinked DAC (CS-DAC) and l-cysteine-functionalized DAC] were used as electrode materials. Electrodes of carbonized CS-DAC beads had a specific capacitance of up to 242 F g(-1) at a current density of 1 A g(-1). These electrodes maintained a capacitance retention of 91.5% after 1000 charge/discharge cycles, suggesting excellent cycling stability. The results indicate that reductive amination of DAC is an effective route for heteroatom doping of carbon materials to be used as electrode active materials for energy storage.
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| 39. |
- Ruan, Changqing, et al.
(författare)
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Cellulose nanofibers prepared via pretreatment based on Oxone® oxidation
- 2017
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 22:12
-
Tidskriftsartikel (refereegranskat)abstract
- Softwood sulfite bleached cellulose pulp was oxidized with Oxone (R) and cellulose nanofibers (CNF) were produced after mechanical treatment with a high-shear homogenizer. UV-vis transmittance of dispersions of oxidized cellulose with different degrees of mechanical treatment was recorded. Scanning electron microscopy (SEM) micrographs and atomic force microscopy (AFM) images of samples prepared from the translucent dispersions showed individualized cellulose nanofibers with a width of about 10 nm and lengths of a few hundred nm. All results demonstrated that more translucent CNF dispersions could be obtained after the pretreatment of cellulose pulp by Oxone (R) oxidation compared with the samples produced without pretreatment. The intrinsic viscosity of the cellulose decreased after oxidation and was further reduced after mechanical treatment. Almost translucent cellulose films were prepared from the dispersions of individualized cellulose nanofibers. The procedure described herein constitutes a green, novel, and efficient route to access CNF.
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| 40. |
- Ruan, Changqing, et al.
(författare)
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Favored Surface-limited Oxidation of Cellulose with Oxone® in Water
- 2017
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 7:64, s. 40600-40607
-
Tidskriftsartikel (refereegranskat)abstract
- A novel method for favored primary alcohol oxidation of cellulose was developed. Cellulose pulp andCladophora nanocellulose were oxidized in a one-pot procedure by Oxone® (2KHSO5$KHSO4$K2SO4)and efficient reaction conditions were identified. The effects of the reaction on the morphology,viscosity and chemical structure of the products obtained were studied. The primary alcohol groupswere oxidized to carboxyl groups and the content of carboxyl groups was determined byconductometric titration. SEM, capillary-type viscometry and XRD were applied to characterize theproducts and to investigate the influence of oxidation. For the first time, low-cost and stable Oxone®was used as a single oxidant to oxidize cellulose into carboxyl cellulose. The oxidation is an inexpensiveand convenient process to produce carboxylic groups on the surface of the cellulose fibers and to makethe cellulose fibers charged. Particularly, this method can avoid the use of halogens and potentially toxicradicals and constitute a green route to access carboxylated cellulose. Further, sodium bromide could beused as a co-oxidant to the Oxone® and increase the carboxylic acid content by 10–20%. The Oxone®oxidation is a promising method for oxidation of cellulose and might facilitate the production of CNC.
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| 41. |
- Ruan, Changqing, et al.
(författare)
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Preparation of Porous 2,3-dialdehyde Cellulose Beads Crosslinked with Chitosan and their Application in Adsorption of Congo Red Dye
- 2018
-
Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 181, s. 200-207
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Tidskriftsartikel (refereegranskat)abstract
- Micrometer sized 2,3-dialdehyde cellulose (DAC) beads were produced via a recently developed method relying on periodate oxidation of Cladophora nanocellulose. The produced dialdehyde groups and pristine hydroxyl groups provided the DAC beads with a vast potential for further functionalization. The sensitivity of the DAC beads to alkaline conditions, however, limits their possible functionalization and applications. Hence, alkaline-stable and porous cellulose beads were prepared via a reductive amination crosslinking reaction between 2,3-dialdehyde cellulose beads and chitosan. The produced materials were thoroughly characterized with different methods. The reaction conditions, including the amount of chitosan used, conditions for reductive amination, reaction temperature and time, were investigated and the maintained morphology of the beads after exposure to 1 M NaOH (aq.) was verified with SEM. Different washing and drying procedures were used and the results were studied by SEM and BET analysis. Furthermore, FTIR, TGA, EDX, XPS, DLS and elemental analysis were performed to characterize the properties of the prepared beads. Finally, the alkaline-stable porous chitosan cross-linked 2,3-dialdehyde cellulose beads were applied as adsorbent for the dye Congo red. The crosslinked beads displayed fast and high adsorption capacity at pH 2 and good desorption properties at pH 12, providing a promising sorption material.
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| 42. |
- Ruan, Changqing, et al.
(författare)
-
Selective C6 Oxidation of Cellulose with Oxone in Water
- 2016
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Konferensbidrag (refereegranskat)abstract
- A novel method for selective C6 primary alcohol oxidation of cellulose, as an alternative to TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl), was developed. Cellulose pulp and Cladophora nanocellulose were selectively oxidized in a one-pot procedure by Oxone (2KHSO5·KHSO4·K2SO4) and efficient reaction conditions were investigated. The effects of the reactions on the morphology, viscosity and chemical structure of the products obtained were studied. The C6 primary alcohol groups were selectively oxidized to carboxyl groups, as testified by solid-state CP/MAS 13C NMR and FTIR, and the content of carboxyl groups was determined by conductometric titration. SEM, capillary-type viscometry and XRD were applied to characterize the products and to investigate the influence of the oxidation. For the first time, low-cost and stable Oxone was used as a single oxidant to oxidize cellulose into C6-carboxyl cellulose. The oxidation is an inexpensive and convenient process to produce carboxylic groups on the surface of the cellulose fibers and to make the cellulose fibers charged. Particularly, this method can avoid the use of halogens and toxic radicals and constitute a green route to access C6-carboxyl cellulose. Further, sodium bromide could be used as a co-oxidant to Oxone and increase carboxylic acid content by 10% to 20%. The Oxone oxidation is a promising alternative to the frequently employed TEMPO-mediated oxidation of cellulose, which might increase the possibility to develop and improve applications of cellulose.
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| 43. |
- Sjöström, Malin, et al.
(författare)
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Outbreak of Cryptosporidium hominis in northern Sweden : persisting symptoms in a 5-year follow-up
- 2022
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Ingår i: Parasitology Research. - : Springer-Verlag New York. - 0932-0113 .- 1432-1955. ; 121, s. 2043-2049
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Tidskriftsartikel (refereegranskat)abstract
- In 2010–2011, a waterborne outbreak of the parasite, Cryptosporidium hominis, affected approximately 27,000 inhabitants in the city of Östersund, Sweden. Previous research suggested that post-infectious symptoms, such as gastrointestinal symptoms and joint pain, could persist for up to 2 years after the initial infection. In this study, we investigated whether the parasite caused post-infectious sequelae for up to 5 years after the outbreak. Prospective cohort study. A randomly selected cohort of individuals residing in Östersund at the time of the outbreak was sent a postal questionnaire in 2011. Responders were sent a follow-up questionnaire in 2016 and completed items on whether they experienced a list of symptoms. We examined whether outbreak cases were more likely than non-cases to report post-infectious symptoms 5 years later. We analysed data using logistic regression and calculated odds ratios with 95% confidence intervals. The analysis included 626 individuals. Among the 262 individuals infected during the outbreak, 56.5% reported symptoms at follow-up. Compared to non-cases, outbreak cases were more likely to report watery diarrhoea, diarrhoea, swollen joints, abdominal pain, bloating, joint discomfort, acid indigestion, alternating bowel habits, joint pain, ocular pain, nausea, and fatigue at the follow-up, after adjusting for age and sex. Our findings suggested that cryptosporidiosis was mainly associated with gastrointestinal- and joint-related post-infectious symptoms for up to 5 years after the infection.
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| 44. |
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| 45. |
- Sundberg, Jonas, et al.
(författare)
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Combined Testing of p16 Tumour-suppressor Protein and Human Papillomavirus in Patients With Oral Leukoplakia and Oral Squamous Cell Carcinoma.
- 2019
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Ingår i: Anticancer research. - : Anticancer Research USA Inc.. - 1791-7530 .- 0250-7005. ; 39:3, s. 1293-1300
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Tidskriftsartikel (refereegranskat)abstract
- Oral leukoplakia (OL) is a potentially malignant oral mucosal disorder. A casual association between OL, oral squamous cell carcinoma (OSCC) and human papillomavirus (HPV) infection has been suggested, but no conclusive evidence has been presented. p16, a tumour-suppressor protein, is used as a surrogate marker for HPV infection. The aim of this study was to investigate how overexpression of p16 correlates with HPV infection in OL and in OSCC.Seventy-four patients with OL and 13 with OSCC with p16 overexpressed, were analyzed by immunohistochemistry visualizing p16 and a real-time polymerase chain reaction (PCR) assay targeting HPV types 6, 11, 16, 18, 31, 33, 35, 39, 45, 52, 56, 58 and 59.Overexpression of p16 was observed in 18% of patients with OL. None of the HPV subtypes were detected by PCR analysis in patients with OL. In the p16-positive OSCC specimens, 38% were also HPV16-positive.Overexpression of p16 was not found to be a reliable biomarker for HPV infection in patients with OL and OSCC.
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| 46. |
- Sundberg, Jonas, et al.
(författare)
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High-risk human papillomavirus in patients with oral leukoplakia and oral squamous cell carcinoma-A multi-centre study in Sweden, Brazil and Romania.
- 2021
-
Ingår i: Oral Diseases. - : Wiley. - 1354-523X .- 1601-0825. ; 27:2, s. 183-192
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Although causal associations between oral leukoplakia (OL), oral squamous cell carcinoma (OSCC) and high-risk human papillomavirus (HR-HPV) have been speculated upon in several reports, conclusive evidence has not been presented. This study investigates whether the number of cases of HR-HPV in OL has increased over time and whether the prevalence of HR-HPV-positive OL differs in various parts of the world.PATIENTS AND METHODS: A total of 432 patients with OL from Sweden, Brazil and Romania were analysed. Patients were divided into historical (1992-2002) and contemporary (2011-2017) cohorts from the respective countries. Seventeen patients with OL developed oral squamous cell carcinoma (OSCC). A real-time PCR assay, targeting HPV sub-types 6,11,16,18,31,33,35,39,45,52,56,58 and 59, was performed to detect HR-HPV in patients with OL.RESULTS: In the Swedish and Romanian cohorts, none of the investigated HPV sub-types were detected. In the Brazilian cohorts, five patients with OL (3%) were positive for HR-HPV, including four patients from the contemporary cohort (HPV 16, 31, 33) and one from the historical cohort (HPV 11). All the cases of OL that transformed into OSCC were HR-HPV-negative, as were the corresponding tumours.CONCLUSIONS: In summary, the prevalence of HR-HPV in OL is low in all the tested countries, and the incidence has not changed over time. HR-HPV in OL does not seem to be a driver of oncogenesis.
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| 47. |
- Tammela, Petter, 1986-, et al.
(författare)
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Laser irradiation of photothermal precursors – a novel approach to produce carbon materials for supercapacitors
- 2024
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Ingår i: ChemSusChem. - : Society Publishing. - 1864-5631 .- 1864-564X. ; , s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- A wide array of carbon materials finds extensive utility across various industrial applications today. Nonetheless, the production processes for these materials continue to entail elevated temperatures, necessitate the use of inert atmospheres, and often involve the handling of aggressive and toxic chemicals. The prevalent method for large-scale carbon material production, namely the pyrolysis of waste biomass and polymers, typically unfolds within the temperature range of 500–700 °C under a nitrogen (N2) atmosphere. Unfortunately, this approach suffers from significant energy inefficiency due to substantial heat loss over extended processing durations. In this work, we propose an interesting alternative: the carbonization of photothermal nanocellulose/polypyrrole composite films through CO2 laser irradiation in the presence of air. This innovative technique offers a swift and energy-efficient means of preparing carbon materials. The unique interaction between nanocellulose and polypyrrole imparts the film with sufficient stability to retain its structural integrity post-carbonization. This breakthrough opens up new avenues for producing binder-free electrodes using a rapid and straightforward approach. Furthermore, the irradiated film demonstrates specific and areal capacitances of 159 F g−1 and 62 μF cm−2, respectively, when immersed in a 2 M NaOH electrolyte. These values significantly surpass those achieved by current commercial activated carbons. Together, these attributes render CO2-laser carbonization an environmentally sustainable and ecologically friendly method for carbon material production.
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| 48. |
- Tikhomirov, Evgenii, et al.
(författare)
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Impact of polymer chemistry on critical quality attributes of selective laser sintering 3D printed solid oral dosage forms
- 2023
-
Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 2590-1567. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to investigate the influence of polymer chemistry on the properties of oral dosage forms produced using selective laser sintering (SLS). The dosage forms were printed using different grades of polyvinyl alcohol or copovidone in combination with indomethacin as the active pharmaceutical ingredient. The properties of the printed structures were assessed according to European Pharmacopoeia guidelines at different printing temperatures and laser scanning speeds in order to determine the suitable printing parameters.The results of the study indicate that the chemical properties of the polymers, such as dynamic viscosity, degree of hydrolyzation, and molecular weight, have significant impact on drug release and kinetics. Drug release rate and supersaturation can be modulated by selecting the appropriate polymer type. Furthermore, the physical properties of the dosage forms printed under the same settings are influenced by the selected polymer type, which determines the ideal manufacturing settings.This study demonstrates how the chemical properties of the polymer can determine the appropriate choice of manufacturing settings and the final properties of oral dosage forms produced using SLS.
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| 49. |
- Tikhomirov, Evgenii, et al.
(författare)
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In situ thermal image analysis of selective laser sintering for oral dosage form manufacturing
- 2023
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier. - 0731-7085 .- 1873-264X. ; 231
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Tidskriftsartikel (refereegranskat)abstract
- Additive Manufacturing (AM) is a fast-growing approach to produce personalized oral dosage forms. Even though some AM technologies are promising as alternative to conventional compounding with resulting dosage manipulation, they still suffer from a lack of quality control. Due to the high regulatory demands and standards applied to dosage forms in the case of dose accuracy and tablet properties such as friability, effective quality control is a key feature in promoting AM as a valid technology for patient-tailored medications. One of the AM techniques used is selective laser sintering, which allows for capturing the surface state layer-by-layer during the printing process. It provides the opportunity to apply non-destructive quality control based on image analysis extracting essential data at each layer of the sintering process. This work is devoted to establishing the value of data gathered via thermal image analysis for the subsequent quality control.
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| 50. |
- Tikhomirov, Evgenii, et al.
(författare)
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Selective laser sintering additive manufacturing of dosage forms : Effect of powder formulation and process parameters on the physical properties of printed tablets
- 2023
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Ingår i: International Journal of Pharmaceutics. - : Elsevier. - 0378-5173 .- 1873-3476. ; 635
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Tidskriftsartikel (refereegranskat)abstract
- Large batches of placebo and drug-loaded solid dosage forms were successfully fabricated using selective laser sintering (SLS) 3D printing in this study. The tablet batches were prepared using either copovidone (N-vinyl-2-pyrrolidone and vinyl acetate, PVP/VA) or polyvinyl alcohol (PVA) and activated carbon (AC) as radiation absorbent, which was added to improve the sintering of the polymer. The physical properties of the dosage forms were evaluated at different pigment concentrations (i.e., 0.5 and 1.0 wt%) and at different laser energy inputs. The mass, hardness, and friability of the tablets were found to be tunable and structures with greater mass and mechanical strength were obtained with increasing carbon concentration and energy input. Amorphization of the active pharmaceutical ingredient in the drug-loaded batches, containing 10 wt% naproxen and 1 wt% AC, was achieved in-situ during printing. Thus, amorphous solid dispersions were prepared in a single-step process and produced tablets with mass losses below 1 wt%. These findings show how the properties of dosage forms can be tuned by careful selection of the process parameters and the powder formulation. SLS 3D printing can therefore be considered to be an interesting and promising technique for the fabrication of personalized medicines.
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