| 1. |
- Munthe, Christian, 1962
(author)
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Precaution and Ethics: Handling risks, uncertainties and knowledge gaps in the regulation of new biotechnologies
- 2017
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Book (other academic/artistic)abstract
- This volume outlines and analyses ethical issues actualized by applying a precautionary approach to the regulation of new biotechnologies. It presents a novel way of categorizing and comparing biotechnologies from a precautionary standpoint. Based on this, it addresses underlying philosophical problems regarding the ethical assessment of decision-making under uncertainty and ignorance, and discusses how risks and possible benefits of such technologies should be balanced from an ethical standpoint. It argues on conceptual and ethical grounds for a technology neutral regulation as well as for a regulation that not only checks new technologies but also requires old, inferior ones to be phased out. It demonstrates how difficult ethical issues regarding the extent and ambition of precautionary policies need to be handled by such a regulation, and presents an overarching framework for doing so.
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| 2. |
- Eivazihollagh, Alireza, et al.
(author)
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On chelating surfactants : Molecular perspectives and application prospects
- 2019
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In: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 278, s. 688-705
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Journal article (peer-reviewed)abstract
- Chelating agents, molecules that very strongly coordinates certain metal ions, are used industrially as well as in consumer products to minimize disturbances and increase performance of reactions and applications. The widely used sequestering agents, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) belong to this branch of readily water-soluble compounds. When these chemical structures also have hydrophobic parts, they are prone to adsorb at air-water interfaces and to self-assemble. Such bifunctional molecules can be called chelating surfactants and will have more extended utilization prospects than common chelating agents or ordinary ionic surfactants. The present review attempts to highlight the fundamental behavior of chelating surfactants in solution and at interfaces, and their very specific interactions with metal ions. Methods to recover chelating surfactants from metal chelates are also described. Moreover, utilization of chelating surfactants in applications for metal removal in environmental engineering and mineral processing, as well as for metal control in the fields of biology, chemistry and physics, is exemplified and discussed.
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| 3. |
- Jansson, Ronnie, et al.
(author)
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Functionalized silk assembled from a recombinant spider silk fusion protein (Z-4RepCT) produced in the methylotrophic yeast Pichia pastoris
- 2016
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In: Biotechnology Journal. - : Wiley-VCH Verlagsgesellschaft. - 1860-6768 .- 1860-7314. ; 11:5, s. 687-699
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Journal article (peer-reviewed)abstract
- Functional biological materials are a growing research area with potential applicability in medicine and biotechnology. Using genetic engineering, the possibility to introduce additional functions into spider silk-based materials has been realized. Recently, a recombinant spider silk fusion protein, Z-4RepCT, was produced intracellularly in Escherichia coli and could after purification self-assemble into silk-like fibers with ability to bind antibodies via the IgG-binding Z domain. In this study, the use of the methylotrophic yeast Pichia pastoris for production of Z-4RepCT has been investigated. Temperature, pH and production time were influencing the amount of soluble Z-4RepCT retrieved from the extracellular fraction. Purification of secreted Z-4RepCT resulted in a mixture of full-length and degraded silk proteins that failed to self-assemble into fibers. A position in the C-terminal domain of 4RepCT was identified as being subjected to proteolytic cleavage by proteases in the Pichia culture supernatant. Moreover, the C-terminal domain was subjected to glycosylation during production in P. pastoris. These observed alterations of the CT domain are suggested to contribute to the failure in fiber assembly. As alternative approach, Z-4RepCT retrieved from the intracellular fraction, which was less degraded, was used and shown to retain ability to assemble into silk-like fibers after enzymatic deglycosylation.
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| 4. |
- He, Wenxiao, 1985
(author)
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Biomimetic Formation of Calcium Phosphate Based Nanomaterials
- 2014
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Doctoral thesis (other academic/artistic)abstract
- The intercellular material in bone is a nanocomposite of aligned “hard” inorganics—calcium phosphate (CaP) platelets embedded in the long-range ordered “soft” organic collagen matrix. This elaborate structural arrangement redeems the weaknesses of the individual components (being soft protein or brittle mineral) and gives bone its excellent mechanical properties for the protection and support of our bodies. The structural order and hierarchy in the soft matrix is organized via self-assembly of collagen molecules and is reinforced by intermolecular crosslinking. The subsequent growth of “hard” crystallites inside the “soft” matrix compartments, likely through the deposition of a transient amorphous calcium phosphate (ACP) phase, results in the interpenetrated composite structure.The aim of this thesis was to prepare synthetic mimetics of “hard” material (CaP) with well-defined nanostructures, soft organic matrices with long-range order and interpenetrated composites composing of the two. The work was inspired by the material deposition process in natural bone. Lyotropic liquid crystal (LC) phases self-assembled by block copolymers were used to mimic the structural order of the collagen matrix. Both the inorganic morphogenesis of CaP in LCs and the controlled crystallization of ACP were investigated. To explore ordered organic matrices, crosslinking of the LCs and the self-assembly of an amphiphilic peptide with designed sequence were performed. In addition, controlled mineralization within crosslinked LCs was examined for the formation of nanocomposites.ACP nanospheres, CaP nanowires and nanosheets were prepared from LCs via templated growth. The ACP nanospheres were capable of transforming into bone-like apatite by controlled aging in water and the prepared nanoparticles were shown to affect osteoblast gene expression. Dicalcium phosphate crystals (brushite and monetite) with structural hierarchy and distinct features were also grown in LCs through epitaxial overgrowth or a self-organization regime. Polymerized LCs were successfully prepared from a modified block copolymer (diacrylate derivative of Pluronic® F127), which served as a resilient matrix for the deposition of ACP nanospheres. A subsequent in situ crystallization of ACP into bone-like apatite resulted in mechanically stable composites retaining nanostructures that resembled that of natural bone. An amphiphilic peptide was designed using mainly natural amino acids and it was shown to self-assemble into distinct structures at different concentrations. Based upon the results presented in this thesis, nanomaterials with assorted structures can be further designed for bio-related applications.
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| 5. |
- Guo, Weijin, et al.
(author)
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Synthetic Paper Separates Plasma from Whole Blood with Low Protein Loss
- 2020
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In: Analytical Chemistry. - Washington D.C. : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 92:9, s. 6194-6199
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Journal article (peer-reviewed)abstract
- The separation of plasma from whole blood is the first step in many diagnostic tests. Point-of-care tests often rely on integrated plasma filters, but protein retention in such filters limits their performance. Here, we investigate plasma separation on interlocked micropillar scaffolds ("synthetic paper") by the local agglutination of blood cells coupled with the capillary separation of the plasma. We separated clinically relevant volumes of plasma with high efficiency in a separation time on par with that of state of the art techniques. We investigated different covalent and non-covalent surface treatments (PEGMA, HEMA, BSA, O2 plasma) on our blood filter and their effect on protein recovery, and identified O2 plasma treatment and 7.9 μg/cm2 agglutination antibody as most suitable treatments. Using these treatments, we recovered at least 82% of the blood plasma proteins, more than with state-of-the-art filters. The simplicity of our device and the performance of our approach could enable better point-of-care tests.
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| 6. |
- Anasontzis, George E, 1980
(author)
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Biomass modifying enzymes: From discovery to application
- 2012
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In: Oral presentation at the Chalmers Life Science AoA conference.
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Conference paper (other academic/artistic)abstract
- It has now been realized that the road towards the bio-based economy is a one-way street, leaving gradually the oil-based technology and driving slowly towards a more sustainable society. The current non-biodegradable hydrocarbon fuels and plastics will be replaced by new products which will derive from natural and renewable resources. The synthesis of such biofuels and biochemicals is still challenged by the difficulties to cost efficiently degrade lignocellulosic material to fermentable sugars or to isolate the intact polymers. Biomass degrading and modifying enzymes play an integral role both in the separation of the polymers from the wood network, as well as in their subsequent modification, prior to further product development.Our group interests focus on all levels of applied enzyme research of biomass acting enzymes: Discovery, assay development, production and application. Relevant examples will be provided: What is our strategy for discovering novel microorganisms and enzymes from the tropical forests and grasslands of Vietnam? How do we design novel real-world assays for enzyme activity determination? Which are the bottlenecks in the enzymatic cellulose hydrolysis? How enzymes can be used to produce high added value compounds from biomass?
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| 7. |
- Andersson, Helene, 1983, et al.
(author)
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Effects of molecular weight on permeability and microstructure of mixed ethyl-hydroxypropyl-cellulose films
- 2013
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In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 48:1-2, s. 240-248
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Journal article (peer-reviewed)abstract
- Films of ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) can be used for extended release coatings in oral formulations. The permeability and microstructure of free EC/HPC films with 30% w/w HPC were studied to investigate effects of EC molecular weight. Phase separation during film spraying and subsequent HPC leaching after immersion in aqueous media cause pore formation in such films. It was found that sprayed films were porous throughout the bulk of the films after water immersion. The molecular weight affected HPC leaching, pore morphology and film permeability; increasing the molecular weight resulted in decreasing permeability. A model to distinguish the major factors contributing to diffusion retardation in porous films showed that the trend in permeability was determined predominantly by factors associated with the geometry and arrangement of pores, independent of the diffusing species. The film with the highest molecular weight did, however, show an additional contribution from pore wall/permeant interactions. In addition, rapid drying and increasing molecular weight resulted in smaller pores, which suggest that phase separation kinetics affects the final microstructure of EC/HPC films. Thus, the molecular weight influences the microstructural features of pores, which are crucial for mass transport in EC/HPC films.
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| 8. |
- Vilardell, Anna M., et al.
(author)
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Cold spray as an emerging technology for biocompatible and antibacterial coatings : State of art
- 2015
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In: Journal of Materials Science. - New York : Springer. - 0022-2461 .- 1573-4803. ; 50:13, s. 4441-4462
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Research review (peer-reviewed)abstract
- The use of coatings in biomaterials has been fundamental on the applicability of many medical devices and has helped improve mechanical properties such as wear and fatigue and biological properties such as biocompatibility and bioactivity of implant prosthesis, thus, in essence, ameliorating human quality life. The aim of the present paper is to give a review on cold spray (CS) coating systems that are emerging in orthopedics industry (internal fixation systems and prosthesis) as well as those for antibacterial purposes (in body and touch external surfaces). These studies are very new, the oldest dating from the half of last decade and most deal with the improvement of biocompatibility and bioactivity of hard tissue replacement; therefore, research on biocoatings is in constant development with the aim to produce implant surfaces that provide a balance between cell adhesion and low cytotoxicity, mechanical properties, and functionalization. CS offers many advantages over conventional high-temperature processes and seems to be able to become competitive in front of the low-temperature techniques. It is mainly cost effective, appropriate for oxygen-sensitive materials, and environmentally green. It basically involves the use of feedstock material in powder form, which is supersonically sprayed onto the appropriate substrate but without any melting as it occurs in conventional thermal spray processes. Biocompatible metallic materials and polymers have been successfully deposited by this method because it is based on the plasticity of the coating material; pure ceramic deposits, for example of hydroxyapatite, are still a challenge.
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| 9. |
- Martinez Avila, Hector, 1985
(author)
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Biofabrication, Biomechanics and Biocompatibility of Nanocellulose-based Scaffolds for Auricular Cartilage Regeneration
- 2015
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Doctoral thesis (other academic/artistic)abstract
- In about 2:10,000 births the external part of the ear, the auricle, is severely malformed or absent. Furthermore, tumors and trauma can cause defects to the auricle. For patients with dysplasia of the auricle, and especially for children, an inconspicuous outer appearance with life-like auricles is important for their psychological and emotional well being as well as their psycho-social development. Auricular reconstruction remains a great challenge due to the complexity of surgical reconstruction using rib cartilage. Despite the advances in stem cell technology and biomaterials, auricular cartilage tissue engineering (TE) is still in an early stage of development due to critical requirements demanding appropriate mechanical properties and shape stability of the tissue-engineered construct. This thesis has focused on developing patient-specific tissue-engineered auricles for one-step surgery using a novel biomaterial, bacterial nanocellulose (BNC), seeded with human nasoseptal chondrocytes (hNC) and bone marrow mononuclear cells (MNC).Biomechanical properties of human auricle cartilage were measured and used as a benchmark for tuning BNC properties. In order to meet the biomechanical requirements, a scaffold with bilayer architecture composed of a dense BNC support layer and a macroporous structure was designed. Firstly, the biocompatibility of the dense BNC layer was investigated, demonstrating a minimal foreign body response according to standards set forth in ISO 10993. Secondly, different methods to create macroporous BNC scaffolds were studied and the redifferentiation capacity of hNCs was evaluated in vitro; revealing that macroporous BNC scaffolds support cell ingrowth, proliferation and neocartilage formation. The bilayer BNC scaffold was biofabricated and tested for endotoxins and cytotoxicity before evaluating in long-term 3D culture, and subsequently in vivo for eight weeks—in an immunocompromised animal model. The results demonstrated that the non-pyrogenic and non- cytotoxic bilayer BNC scaffold offers a good mechanical stability and maintains a structural integrity, while providing a porous 3D environment that is suitable for hNCs and MNCs to produce neocartilage, in vitro and in vivo. Furthermore, patient-specific auricular BNC scaffolds with bilayer architecture were biofabricated and seeded with autologous rabbit auricular chondrocytes (rAC) for implantation in an immunocompetent rabbit model for six weeks. The results demonstrated the shape stability of the rAC-seeded scaffolds and neocartilage depositions in the immunocompetent autologous grafts. 3D bioprinting was also evaluated for biofabrication of patient-specific, chondrocyte-laden auricular constructs using a bioink composed of nanofibrillated cellulose and alginate. Bioprinted auricular constructs showed an excellent shape and size stability after in vitro culture. Moreover, this bioink supports redifferentiation of hNCs while offering excellent printability, making this a promising approach for auricular cartilage TE. Furthermore, the use of bioreactors is essential for the development of tissue-engineered cartilage in vitro. Thus, a compression bioreactor was utilized to apply dynamic mechanical stimulation to cell-seeded constructs as a means to enhance production of extracellular matrix in vitro.In this work, a potential clinical therapy for auricular reconstruction using tissue-engineered auricles is demonstrated; where BNC is proposed as a promising non-degradable biomaterial with good chemical and mechanical stability for auricular cartilage TE. Although the primary focus of this thesis is on auricular reconstruction, the methods developed are also applicable in the regeneration of other cartilage tissues such as those found in the nose, trachea, spine and articular joints.
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| 10. |
- Hartzén, Ann-Sofie, et al.
(author)
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The material expression of new pulp-fibre reinforced composites in relation to other material categories
- 2016
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In: Proceedings - D and E 2016. - Amsterdam : Universidad de los Andes. - 9789461867254 ; , s. 191-200
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Conference paper (peer-reviewed)abstract
- To help bridge the gap between the science lab and commercial production there is a need for a better understanding of how new bio-based materials are perceived by users. The aim of the studies in this paper was to identify the material expression, sensorial properties and semantic dimensions of a group of pulp-fibre reinforced composites that are still in the research phase and how these relate to other, better-known materials already on the market. The studies involved 21 different materials, divided into different material groups such as metals, solid woods, wood fibre materials, plastic and fibre-reinforced composites in which the pulp-fibre reinforced composites were included. The materials were evaluated for meaning in a product semantic study and for sensory perception in a sensorial study. The results of the semantic study gave two underlining dimensions explaining most of the variations between the materials, Quality and Naturalness. These dimensions also had strong correlations to some of the sensorial properties. The results indicate that the pulp-fibre reinforced composites were not perceived as having high quality or expressing naturalness. They were hard to distinguish from the plastics in the study. The implications for further research and material development are discussed.
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