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  • 1.
    Alves, L.
    et al.
    University of Coimbra, Department of Chemistry, Coimbra, Portugal .
    Medronho, B.
    Faculty of Sciences and Technology, Centre for Mediterranean Bioresources and Food, University of Algarve, Ed. 8, Campus de Gambelas, Faro, Portugal .
    Antunes, F. E.
    University of Coimbra, Department of Chemistry, Coimbra, Portugal .
    Fernández-García, M. P.
    IFIMUP and in - Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science, University of Porto, Porto, Portugal .
    Ventura, J.
    IFIMUP and in - Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science, University of Porto, Porto, Portugal .
    Araújo, J. P.
    IFIMUP and in - Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science, University of Porto, Porto, Portugal .
    Romano, A.
    Faculty of Sciences and Technology, Centre for Mediterranean Bioresources and Food, University of Algarve, Ed. 8, Campus de Gambelas, Faro, Portugal .
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore .
    Unusual extraction and characterization of nanocrystalline cellulose from cellulose derivatives2015Inngår i: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 210, s. 106-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Unlike many nanomaterials, nanocrystalline cellulose (CNC) is not synthesized from molecular or atomic components but rather extracted from naturally occurring cellulose. Undoubtedly, the exploitation of CNCs will become a bridge between nanoscience and natural resource products, which could play a major role in reviving the forest industry. In this work, CNC was successfully extracted from unusual sources, hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose (CMC). The extracted crystallites were purified and further characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and dynamic light scattering (DLS). The average size of the CNCs extracted from HPMC and CMC was found to be less (and with lower zeta potential) than the ones extracted from microcrystalline cellulose (MCC). On the other hand, FTIR and XRD revealed that native HPMC and CMC are unexpectedly highly crystalline and hence can be used as a source for CNCs. © 2014 Elsevier B.V.All rights reserved.

  • 2.
    Alves, Luis
    et al.
    CQC, University of Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. CQC, University of Coimbra, Portugal; Lund University.
    Klotz, Björn
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Böttcher, Axel
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Haake, Hans-Martin
    BASF Personal Care and Nutrition GmbH, Düsseldorf, Germany.
    Antunes, Filipe E.
    CQC, University of Coimbra, Portugal.
    On the rheology of mixed systems of hydrophobically modified polyacrylate microgels and surfactants: Role of the surfactant architecture2018Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 513, s. 489-496Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hypothesis The rheological control of suspensions is of key interest in the formulation design. A chemically cross-linked hydrophobically modified poly(acrylic acid) (HMCL-PAA), used as rheology modifier, is pH sensitive and shows swelling behavior above a critical pH due to the ionization of the acrylic acid groups. At low pH, HMCL-PAA suspensions are liquid and turbid. The binding of surfactants to HMCL-PAA, at low pH conditions, can result in significant changes on rheology and transparency of the polymeric suspensions, due to the swelling of the microgel particles. Experiments The influence of surfactants addition on the rheological properties and transparency of HMCL-PAA suspensions was determined. A systematic study was performed using different types of surfactants (ionic, non-ionic and zwitterionic). Findings The gelation efficiency of HMCL-PAA suspensions at low pH is strongly dependent on surfactant architecture: ionic surfactants are found to be much more efficient than non-ionic or zwitterionic surfactants. Ionic surfactants lead to a liquid-to-gel transition accompanied by an increase of transparency of the suspensions. Among the ionic surfactants, anionics show stronger interactions with the polymer. Also the surfactant hydrophobicity is relevant; the more hydrophobic the surfactant, the stronger is the binding to the polymer and thus the larger the particle swelling. 

  • 3.
    Alves, Luis
    et al.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol MEDITBIO, Campus Gambelas,Ed 8, P-8005139 Faro, Portugal..
    Antunes, Filipe E.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Topgaard, Daniel
    Lund Univ, Ctr Chem & Chem Engn, Dept Chem, Div Phys Chem, S-22100 Lund, Sweden..
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Nanyang Technol Univ, Mat Sci & Engn, Singapore 639798, Singapore.
    Dissolution state of cellulose in aqueous systems. 1. Alkaline solvents2016Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 1, s. 247-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The understanding of the state of dissolution of cellulose in a certain solvent is a critical step forward in the development of new efficient solvent systems for cellulose. Nevertheless, obtaining such information is not trivial. Recently, polarization transfer solid-state NMR (PTssNMR) was shown to be a very promising technique regarding an efficient and robust characterization of the solution state of cellulose. In the present study, combining PTssNMR, microscopic techniques and X-ray diffraction, a set of alkaline aqueous systems are investigated. The addition of specific additives, such as urea or thiourea, to aqueous NaOH based systems as well as the use of an amphiphilic organic cation, is found to have pronounced effects on the dissolution efficiency of cellulose. Additionally, the characteristics of the regenerated material are strongly dependent on the dissolution system; typically less crystalline materials, presenting smoother morphologies, are obtained when amphiphilic solvents or additives are used.

  • 4.
    Alves, Luis
    et al.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol MEDITBIO, Campus Gambelas,Ed 8, P-8005139 Faro, Portugal..
    Antunes, Filipe E.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal..
    Topgaard, Daniel
    Lund Univ, Ctr Chem & Chem Engn, Dept Chem, Div Phys Chem, SE-22100 Lund, Sweden..
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Nanyang Technol Univ, Mat Sci & Engn, Singapore 639798, Singapore.
    Dissolution state of cellulose in aqueous systems. 2. Acidic solvents2016Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 151, s. 707-715Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose is insoluble in water but can be dissolved in strong acidic or alkaline conditions. How well dissolved cellulose is in solution and how it organizes are key questions often neglected in literature. The typical low pH required for dissolving cellulose in acidic solvents limits the use of typical characterization techniques. In this respect, Polarization Transfer Solid State NMR (PT ssNMR) emerges as a reliable alternative. In this work, combining PT ssNMR, microscopic techniques and X-ray diffraction, a set of different acidic systems (phosphoric acid/water, sulfuric acid/glycerol and zinc chloride/water) is investigated. The studied solvent systems are capable to efficiently dissolve cellulose, although degradation occurs to some extent. PT ssNMR is capable to identify the liquid and solid fractions of cellulose, the degradation products and it is also sensitive to gelation. The materials regenerated from the acidic dopes were found to be highly sensitive to the solvent system and to the presence of amphiphilic additives in solution.

  • 5.
    Alves, Luis
    et al.
    Univ Coimbra, Coimbra, Portugal.
    Medronho, Bruno
    Univ Algarve, Faro, Portugal.
    Filipe, Alexandra
    Univ Algarve, Faro, Portugal.
    Antunes, Filipe E.
    Univ Coimbra, Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik. Univ Coimbra, Coimbra, Portugal; Lund Univ, Lund.
    Topgaard, Daniel
    Lund Univ, Lund.
    Davidovich, Irina
    Technion Israel Inst Technol, Haifa, Israel.
    Talmon, Yeshayahu
    Technion Israel Inst Technol, Haifa, Israel.
    New Insights on the Role of Urea on the Dissolution and Thermally-Induced Gelation of Cellulose in Aqueous Alkali2018Inngår i: GELS, ISSN 2310-2861, Vol. 4, nr 4, artikkel-id 87Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The gelation of cellulose in alkali solutions is quite relevant, but still a poorly understood process. Moreover, the role of certain additives, such as urea, is not consensual among the community. Therefore, in this work, an unusual set of characterization methods for cellulose solutions, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR) and diffusion wave spectroscopy (DWS) were employed to study the role of urea on the dissolution and gelation processes of cellulose in aqueous alkali. Cryo-TEM reveals that the addition of urea generally reduces the presence of undissolved cellulose fibrils in solution. These results are consistent with PTssNMR data, which show the reduction and in some cases the absence of crystalline portions of cellulose in solution, suggesting a pronounced positive effect of the urea on the dissolution efficiency of cellulose. Both conventional mechanical macrorheology and microrheology (DWS) indicate a significant delay of gelation induced by urea, being absent until ca. 60 degrees C for a system containing 5wt % cellulose, while a system without urea gels at a lower temperature. For higher cellulose concentrations, the samples containing urea form gels even at room temperature. It is argued that since urea facilitates cellulose dissolution, the high entanglement of the cellulose chains in solution (above the critical concentration, C*) results in a strong three-dimensional network.

  • 6.
    Costa, Carolina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Medronho, Bruno
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik. University of Algarve, Faro, Portugal.
    Filipe, Alexandra
    University of Algarve, Faro, Portugal.
    Mira, Isabel
    RISE, Stockholm.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Emulsion formation and stabilization by biomolecules: The leading role of cellulose2019Inngår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 11, nr 10, artikkel-id 1570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Emulsion stabilization by native cellulose has been mainly hampered because of its insolubility in water. Chemical modification is normally needed to obtain water-soluble cellulose derivatives. These modified celluloses have been widely used for a range of applications by the food, cosmetic, pharmaceutic, paint and construction industries. In most cases, the modified celluloses are used as rheology modifiers (thickeners) or as emulsifying agents. In the last decade, the structural features of cellulose have been revisited, with particular focus on its structural anisotropy (amphiphilicity) and the molecular interactions leading to its resistance to dissolution. The amphiphilic behavior of native cellulose is evidenced by its capacity to adsorb at the interface between oil and aqueous solvent solutions, thus being capable of stabilizing emulsions. In this overview, the fundamentals of emulsion formation and stabilization by biomolecules are briefly revisited before different aspects around the emerging role of cellulose as emulsion stabilizer are addressed in detail. Particular focus is given to systems stabilized by native cellulose, either molecularly-dissolved or not (Pickering-like effect). 

  • 7.
    Costa, Carolina
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Mira, Isabel
    RISE, Stockholm.
    Benjamins, Jan-Willem
    RISE, Stockholm.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Interfacial activity and emulsion stabilization of dissolved cellulose2019Inngår i: Journal of Molecular Liquids, ISSN 0167-7322, E-ISSN 1873-3166, Vol. 292, artikkel-id 111325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Some aspects of the interfacial behavior of cellulose dissolved in an aqueous solvent were investigated. Cellulose was found to significantly decrease the interfacial tension (IFT) between paraffin oil and 85 wt% phosphoric acid aqueous solutions. This decrease was similar in magnitude to that displayed by non-ionic cellulose derivatives. Cellulose's interfacial activity indicated a significant amphiphilic character and that the interfacial activity of cellulose derivatives is not only related to the derivatization but inherent in the cellulose backbone. This finding suggests that cellulose would have the ability of stabilizing dispersions, like oil-in-water emulsions in a similar way as a large number of cellulose derivatives. In its molecularly dissolved state, cellulose proved to be able to stabilize emulsions of paraffin in the polar solvent on a short-term. However, long-term stability against drop-coalescence was possible to achieve by a slight change in the amphiphilicity of cellulose, effected by a slight increase in pH. These emulsions exhibited excellent stability against coalescence/oiling-off over a period of one year. Ageing of the cellulose solution before emulsification (resulting in molecular weight reduction) was found to favour the creation of smaller droplets. 

  • 8.
    Cuomo, Francesca
    et al.
    Univ Molise, Campobasso, Italy.
    Cofelice, Martina
    Univ Molise, Campobasso, Italy.
    Venditti, Francesco
    Univ Molise, Campobasso, Italy.
    Ceglie, Andrea
    Univ Molise, Campobasso, Italy.
    Miguel, Maria
    Coimbra Univ, Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund Univ, Lund.
    Lopez, Francesco
    Univ Molise, Campobasso, Italy.
    In-vitro digestion of curcumin loaded chitosan-coated liposomes2018Inngår i: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 168, s. 29-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Liposomes are considered a major route for encapsulation of hydrophilic and hydrophobic molecules. Chitosan coated liposomes could represent an alternative way as a carrier for delivery of drugs in human body. In this study the preparation and applicability of chitosan-coated liposomes containing curcumin as well as curcumin loaded anionic liposomes were evaluated. The applicability of the carriers was tested by means of an in vitro digestion procedure allowing for measurement of the bioaccessibility of ingested curcumin. Values of diameter, polydispersity index and surface charge for curcumin loaded anionic liposomes obtained through dynamic light scattering and zeta-potential measurements were 129 nm, 0.095 and -49 mV, respectively. After chitosan-coating, diameter and polydispersity index remain unvaried while the surface charge gets positive. Slightly higher curcumin concentrations were found after the mouth and the stomach digestion phases when curcumin was loaded in anionic liposomes. On the contrary, after the intestinal phase, a higher percentage of curcumin was found when chitosan-coated liposomes were used as carrier, both in the raw digesta and in the bile salt micellar phase. It was shown that the presence of a positively charged surface allows a better absorption of curcumin in the small intestine phase, which increases the overall curcumin bioavailability. The mechanism behind these results can be understood from the composition of different environments generated by the digestive fluids that differently interact with anionic or cationic surfaces. 

  • 9.
    Cuomo, Francesca
    et al.
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Lopez, Francesco
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Piludu, Marco
    Univ Cagliari, Dipartimento Sci Biomed, I-09042 Monserrato, CA, Italy.
    Miguel, Maria G.
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund Univ, Phys Chem, S-22100 Lund, Sweden.
    Ceglie, Andrea
    Univ Molise, Dipartimento Agr, Ambiente Alimenti DIAAA, I-86100 Campobasso, Italy.
    Release of small hydrophilic molecules from polyelectrolyte capsules: Effect of the wall thickness2015Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 447, s. 211-216Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polymer nanocapsules assembled on cationic liposomes have been built through the layer-by-layer (LbL) technique. Chitosan and alginate, two biocompatible polyelectrolytes, were used to cover the template, where the Rhodamine B was previously loaded. The multishell formed with the alternate deposition of the polyelectrolytes, according to the principles of the LbL assembly, was supposed to change the permeability of the capsule wall. The thickness of the multishell was seen increasing with the number of layers deposited through the observations with the Transmission Electron Microscope. The permeability of the capsules was studied through Rhodamine B release assays. Nanocapsules with seven layers of polyelectrolytes released the dye slowly compared to the capsules with three or five layers. The Ritger-Peppas model was applied to investigate the release mechanisms and a non-Fickian transport behavior was detected regardless of the number of layers. Values of diffusion coefficients of Rhodamine B through the capsule wall were also calculated. (C) 2014 Elsevier Inc. All rights reserved.

  • 10.
    Eivazihollagh, Alireza
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Bäckström, Joakim
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Carlsson, Fredrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för naturvetenskap.
    Ibrahem, Ismail
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    One-pot synthesis of cellulose-templated copper nanoparticles with antibacterial properties2017Inngår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 187, s. 170-172Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report a facile in situ synthesis of spherical copper nanoparticles (NPs) templated by a gelled cellulose II matrix under alkaline aqueous reaction conditions. In under 20 min, the hybrid material could be obtained in a one-pot reaction. Field-emission scanning electron microscopy (FE-SEM) revealed that the polycrystalline NPs of 200–500 nm were well distributed in the regenerated cellulose matrix. The average Cu crystallite size was of the order of 20 nm, as estimated from both X-ray diffraction (XRD) and FE-SEM. XRD data also indicated that the composite contained up to approximately 20% Cu2O. In suspensions containing the hybrid material, growth of Escerichia coli and Staphylococcus aureus strains was inhibited by 80% and 95%, respectively, after 72 h. The synthesis procedure offers a general approach to designing various low-cost hybrid materials of almost any shape, and the concept could be extended to utilization areas such as catalysis, functional textiles, and food packaging as well as to electronic applications.

  • 11.
    Lindman, Björn
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund Univ, Ctr Chem & Chem Engn, Dept Chem, Div Phys Chem, SE-22100 Lund, Sweden.
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol, P-8005139 Faro, Portugal..
    The Subtleties of Dissolution and Regeneration of Cellulose: Breaking and Making Hydrogen Bonds2015Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 10, nr 3, s. 3811-3814Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Cellulose dissolution and regeneration are old topics that have recently gained renewed attention. This is reflected in both applications - earlier and novel - and in scientific controversies. There is a current discussion in the literature on the balance between hydrogen bonding and hydrophobic interactions in controlling the solution behavior of cellulose. Some of the key ideas are recalled.

  • 12.
    Lindman, Björn
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lunds Universitet.
    Medronho, Bruno
    University of Algarve, Faro, Portugal.
    Alves, Luís
    University of Coimbra, Portugal.
    Costa, Carolina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena2017Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, nr 35, s. 23704-23718Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.

  • 13.
    Lindman, Björn
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal.
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol MEDITBIO, Campus Gambelas,Ed 8, P-8005139 Faro, Portugal.
    Karlström, Gunnar
    Lund Univ, Div Theoret Chem, Dept Chem, Ctr Chem & Chem Engn, SE-22100 Lund, Sweden.
    Clouding of nonionic surfactants2016Inngår i: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 22, s. 23-29Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Nonionic surfactants have broad applications such as cleaning and dispersion stabilization, which frequently are hampered by strong temperature sensitivities. As manifested by clouding and decreased solubility with increasing temperature, the interaction between water and the oligo(oxyethylene) head-groups is becoming less favorable. Different aspects of surfactant self-assembly, like the critical micelle concentration, micelle size and shape, intermicellar interactions and phase separation phenomena are reviewed as well as suggested underlying causes of the temperature dependence. Furthermore, the effect of cosolutes on clouding and the behavior of related systems, non-aqueous solutions and nonionic polymers, are examined. (C) 2016 Elsevier Ltd. All rights reserved.

  • 14.
    Lindman, Björn
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund Univ, Ctr Chem & Chem Engn, Dept Chem, Div Phys Chem, SE-22100 Lund, Sweden.
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol, P-8005139 Faro, Portugal.
    Theliander, Hans
    Chalmers Univ Engn, Forest Prod & Chem Engn, SE-41296 Gothenburg, Sweden.
    Editorial: Cellulose dissolution and regeneration: systems and interactions2015Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 1, s. 2-3Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Lindman, Björn
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Lund University, Lund; Nanyang Technological University, Singapore, Singapore.
    Nylander, Tommy
    Lund University, Lund.
    Polymer-Surfactant Interactions2017Inngår i: Cosmetic Science and Technology: Theoretical Principles and Applications / [ed] Kazutami Sakamoto, Robert Y. Lochhead, Howard I. Maibach, Yuji Yamashita, Elsevier Inc. , 2017, s. 449-469Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Deposition from oppositely charged polyelectrolyte/surfactant (P/S) systems has numerous industrial applications such as detergency, paints, oil recovery, the pharmaceuticals, food, and biotechnology. Deposition is a delicate balance between the bulk-solution phase behavior of the system and the forces that control the interaction with the surface. Generally, maximum surface excess from polyelectrolyte surfactant mixtures coincides with this phase separation region, and this process is often kinetically controlled. We will discuss how the molecular properties of a range of polymers can be used to tune the properties. If the polymer is not hydrophobic enough, the surfactant binding is too limited to ensure attachment, whereas surfactant binding will be too strong and the phase separation range too limited if the polymer is too hydrophobic. No phase separation will occur if the charge density is too low, but a too-high charge density will cause so strong an association between surfactant and polymer that deposition does not occur. It is important to bear in mind that during the timescale of the application of a formulation, nonequilibrium effects can be significant and utilized to form a layer that is trapped in a nonequilibrium state, which gives the desired surface functionality. 

  • 16.
    Medronho, B.
    et al.
    University of Algarve, Faro, Portugal.
    Filipe, A.
    University of Algarve, Faro, Portugal.
    Costa, Carolina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Romano, A.
    University of Algarve, Faro, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Microrheology of novel cellulose stabilized oil-in-water emulsions2018Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 531, nr 1 December 2018, s. 225-232Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Diffusing wave spectroscopy (DWS) is a powerful optical technique suitable to investigate turbid samples in a nondestructive and reproducible way, providing information on the static and dynamic properties of the system. This includes the relative displacement of emulsion droplets over time and changes in the viscoelastic properties. Here, novel and promising cellulose-based oil-in-water (O/W) emulsions were prepared and studied, for the first time, by DWS. Cellulose plays the role of a novel eco-friendly emulsifying agent. The hydrolysis time of cellulose was observed to affect the average size of the emulsion droplets and their stability; the longer the hydrolysis time, the more dispersed and stable the emulsions were found to be. Additionally, a good complementarity between the microrheology (DWS) and macrorheology (mechanical rheometer) data was found. Our work suggests that DWS is a highly attractive method to investigate the stability, aging and microrheology properties of cellulose-based emulsions, providing valuable insights on their microstructure. This technique is thus highly appealing for the characterization and design of novel emulsion formulations.

  • 17.
    Medronho, Bruno
    et al.
    Univ Algarve, Fac Sci & Technol, Ctr Mediterranean Bioresources & Food, P-8005139 Faro, Portugal.
    Duarte, Hugo
    Univ Algarve, Fac Sci & Technol, Ctr Mediterranean Bioresources & Food, P-8005139 Faro, Portugal.
    Alves, Luis
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal.
    Antunes, Filipe
    Univ Coimbra, Dept Chem, P-3004535 Coimbra, Portugal.
    Romano, Anabela
    Univ Algarve, Fac Sci & Technol, Ctr Mediterranean Bioresources & Food, P-8005139 Faro, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Nanyang Technol Univ, Mat Sci & Engn, Singapore 639798, Singapore.
    Probing cellulose amphiphilicity2015Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 1, s. 58-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose dissolution and regeneration is an increasingly active research field due to the direct relevance for numerous production processes and applications. The problem is not trivial since cellulose solvents are of remarkably different nature and thus the understanding of the subtle balance between the different interactions involved becomes difficult but crucial. There is a current discussion in literature on the balance between hydrogen bonding and hydrophobic interactions in controlling the solution behavior of cellulose. This treatise attempts to review recent work highlighting the marked amphiphilic characteristics of cellulose and role of hydrophobic interactions in dissolution and regeneration. Additionally, a few examples of our own research are discussed focusing on the role of different additives in cellulose solubility. The data does support the amphiphilic behavior of cellulose, which clearly should not be neglected when developing new solvents and strategies for cellulose dissolution and regeneration.

  • 18.
    Singh, P.
    et al.
    CQC, University of Coimbra, Department of Chemistry, 3004-535 Coimbra, Portugal.
    Medronho, B.
    Faculty of Sciences and Technology (MeditBio), Ed. 8, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
    Alves, L.
    CQC, University of Coimbra, Department of Chemistry, 3004-535 Coimbra, Portugal.
    da Silva, G. J.
    Faculty of Pharmacy and Center for Neurosciences and Cell Biology, University of Coimbra, Health Sciences Campus, 3000-5548 Coimbra, Portugal.
    Miguel, M. G.
    CQC, University of Coimbra, Department of Chemistry, 3004-535 Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. CQC, University of Coimbra, Department of Chemistry, 3004-535 Coimbra, Portugal.
    Development of carboxymethyl cellulose-chitosan hybrid micro- and macroparticles for encapsulation of probiotic bacteria2017Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 175, s. 87-95Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel carboxymethyl cellulose-chitosan (CMC-Cht) hybrid micro- and macroparticles were successfully prepared in aqueous media either by drop-wise addition or via nozzle-spray methods. The systems were either physically or chemically crosslinked using genipin as the reticulation agent. The macroparticles (ca. 2 mm) formed are found to be essentially of the core-shell type, while the microparticles (ca. 5 μm) are apparently homogeneous. The crosslinked particles are robust, thermally resistant and less sensitive to pH changes. On the other hand, the physical systems are pH sensitive presenting a remarkable swelling at pH 7.4, while little swelling is observed at pH 2.4. Furthermore, model probiotic bacteria (Lactobacillus rhamnosus GG) was for the first time successfully encapsulated in the CMC-Cht based particles with acceptable viability count. Overall, the systems developed are highly promising for probiotic encapsulation and potential delivery in the intestinal tract with the purpose of modulating gut microbiota and improving human health.

  • 19.
    Singh, Poonam
    et al.
    Univ Coimbra, Coimbra, Portugal.
    Magalhaes, Solange
    Univ Coimbra, Coimbra, Portugal.
    Alves, Luis
    Univ Coimbra, Coimbra, Portugal.
    Antunes, Filipe
    Univ Coimbra, Coimbra, Portugal.
    Miguel, Maria
    Univ Coimbra, Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Medronho, Bruno
    Univ Algarve, Faro, Portugal.
    Cellulose-based edible films for probiotic entrapment2019Inngår i: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 88, s. 68-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Encapsulation with edible films is a promising approach that may solve the disadvantages associated with the use of bioactive compounds as food additives. This is particularly relevant in the case of probiotics, since their stability in food matrices and in the gastrointestinal tract may be rather poor. Therefore, new cellulose-based edible films have been successfully developed and characterized. Sodium carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC) were used for the film preparation and cross-linked with citric acid (CA) under reasonably mild conditions. Model probiotic bacteria (Lactobacillus rhamnosus GG) were incorporated in the films either during the film formation and casting or after the film synthesis, via bacteria diffusion and adsorption. The later approach could efficiently entrap and preserve viable bacteria. The mechanical properties and swelling ability could be tuned by varying the HEC/CMC ratio and the amount of CA. Moreover, the surface area and total pore volume of the films considerably decreased after cross-linking. Overall, these novel films are regarded as promising inexpensive and friendly matrices for food protection and packaging applications.

  • 20.
    Singh, Poonam
    et al.
    Univ Coimbra, Dept Chem, Coimbra, Portugal.
    Medronho, Bruno
    Univ Algarve, Fac Sci & Technol MeditBio, Faro, Portugal.
    dos Santos, Tiago
    i3S, Porto, Portugal; Univ Porto, INEB Inst Engn Biomed, Porto, Portugal.
    Nunes-Correia, Isabel
    Univ Coimbra, CNC Ctr Neurosci & Cell Biol, Coimbra, Portugal.
    Granja, Pedro
    i3S, Porto, Portugal; Univ Porto, INEB Inst Engn Biomed, Porto, Portugal; Univ Porto, ICBAS, Porto, Portugal.
    Miguel, Maria G.
    Univ Coimbra, Dept Chem, Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Univ Coimbra, Dept Chem, Coimbra, Portugal.
    On the viability, cytotoxicity and stability of probiotic bacteria entrapped in cellulose-based particles2018Inngår i: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 82, s. 457-465Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Probiotics are increasingly gaining popularity in vast food applications due to their recognized health benefits to the host. However, their passage through the gastrointestinal (GI) tract is not smooth and a significant number of physiological barriers (e.g. low pH, bile salts, enzymes, peristaltic movements, etc.) may considerably affect their viability. The entrapment of probiotics in protective matrices, such as hydrogel particles, is a feasible approach to minimize cell death. Therefore, in this work, novel cellulose/chitosan-based particles have been developed to entrap model probiotic Lactobacillus rhamnosus GG. The particle aging, storing and stability was studied at different temperatures and in simulated GI fluids with and without cross-linking agents or protein and lipid additives. Moreover, the effect of the particles on a model intestinal cell line was evaluated. The formulations containing casein displayed the best bacterial survival/culturability when exposed to the GI fluids. Overall, the storage and viability of the probiotics were observed to be improved in the different biopolymer-based systems, generally presenting a low toxicity profile to the cell line. Thus, the particles, which were based on carboxymethyl cellulose and chitosan, may be regarded as interesting matrices for probiotic encapsulation and delivery in food products. 

  • 21.
    Singh, Poonam
    et al.
    University of Coimbra, Department of Chemistry, Coimbra, Portugal.
    Medronho, Bruno
    University of Algarve, Campus de Gambelas, Faro, Portugal.
    Valente, Artur J. M.
    University of Coimbra, Department of Chemistry, Coimbra, Portugal.
    Miguel, Maria G.
    University of Coimbra, Department of Chemistry, Coimbra, Portugal.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Exploring the prebiotic effect of cyclodextrins on probiotic bacteria entrapped in carboxymetyl cellulose-chitosan particles2018Inngår i: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 168, nr August 2018, s. 156-162Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work the prebiotic effect of different cyclodextrins, CDs, on the viability of model probiotic bacteria (Lactobacillus rhamnosus GG) encapsulated in carboxymethyl cellulose-chitosan (CMC-Cht) hybrid particles was studied. All the CDs tested were observed to considerably improve the viability (quantitatively like common prebiotics, such as corn starch) and encapsulation efficiency when compared to the CD-free particles, as inferred by plate counting method and fluorescence microscopy. The SEM data suggests that the morphology of the particles, the roughness of the surface and porosity, are dependent on the type of CD and may reflect different interactions between the CDs and the matrix components. The aging and stability of the samples with and without β-CD were further evaluated. Remarkably, the viability count of the CD-doped samples was still reasonably high after one month storage at room temperature with acceptable values for practical uses. Moreover, when the CMC-Cht particles were exposed to in vitro simulated digestion fluids, the cell survival was much enhanced when the particles contained β-CD. 

  • 22.
    Svanedal, Ida
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Andersson, Fredrik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Hedenström, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Satija, Sushil K.
    NIST, Ctr Neutron Res, 100 Bur Dr,MS 6100, Gaithersburg, MD 20899 USA.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik. Univ Coimbra, Dept Chem, Rua Larga, P-3004535 Coimbra, Portugal.
    Rennie, Adrian R.
    Uppsala Univ, Mat Phys, Uppsala, Sweden; Uppsala Univ, Ctr Neutron Scattering, Angstrom Lab, Uppsala, Sweden.
    Molecular Organization of an Adsorbed Layer: A Zwitterionic, pH-Sensitive Surfactant at the Air/Water Interface2016Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 32, nr 42, s. 10936-10945Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Neutron and X-ray reflection measurements have been used to study the structure of the adsorbed layer of a chelating surfactant at the air/liquid interface. The chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (C-12-DTPA) has a large headgroup containing eight donor atoms that can participate in the coordination of metal ions. The donor atoms are also titrating, resulting in an amphoteric surfactant that can adopt a number of differently charged species depending on the pH. Very strong coordination complexes are formed with metal ions, where the metal ion can be considered as part of the surfactant structure, in contrast to monovalent cations that act as regular counterions to the negative net charge. Adsorption was investigated over a large concentration interval, from well below the critical micelle concentration (cmc) to five times the cmc. The most striking result is the maximum in the surface excess found around the cmc, winch is consistent with previous indications from surface tension measurements. Adding divalent metal ions has a limited effect on the adsorption at the air/liquid interface. The reason is the coordination of the metal ion, resulting in compensating deprotonation of the complex. Small variations in the headgroup area of different metal complexes are found, correlating to the conditional stability constants. Adding sodium chloride has a significant effect on the adsorption behavior, and the results indicate that the protonation equilibrium is more important than the ionic strength effects. From combined fits of the neutron and X-ray data, a model that consists of a thick headgroup region and a relatively thin dehydrated tail region is found, and it indicates that the tails are not fully extended and that the limiting area per molecule is determined by the bulky headgroup.

  • 23.
    Yang, Jiayi
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Dahlström, Christina
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för kemiteknik.
    pH-responsive cellulose–chitosan nanocomposite films with slow release of chitosan2019Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, nr 6, s. 3763-3776Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cellulose–chitosan films were preparedusing a physical method in which cellulose andchitosan were separately dissolved via freeze thawingin LiOH/urea and mixed in different proportions, theresulting films being cast and regenerated in water/ethanol. X-ray diffraction and Fourier transforminfrared spectroscopy (FT-IR) spectroscopy verifiedthe composition changes in the nanocomposites due todifferent mixing ratios between the polymers. Tensilestress–strain measurements indicated that the mechan-ical performance of the cellulose–chitosan nanocom-posites slightly worsened with increasing chitosancontent compared with that of films comprisingcellulose alone. Field emission scanning electronmicroscopy revealed the spontaneous formation ofnanofibers in the films; these nanofibers were subse-quently ordered into lamellar structures. Water uptakeand microscopy analysis of film thickness changesindicated that the swelling dramatically increased atlower pH and with increasing chitosan content, thisbeing ascribed to the Gibbs–Donnan effect. Slowmaterial loss appeared at acidic pH, as indicated by aloss of weight, and quantitative FT-IR analysisconfirmed that chitosan was the main componentreleased.Asample containing 75% chitosan reached amaximum swelling ratio and weight loss of 1500%and 55 wt%, respectively, after 12 h at pH 3. Thestudy presents a novel way of preparing pH-responsivecellulose–chitosan nanocomposites with slow-releasecharacteristics using an environmentally friendlyprocedure and without any chemical reactions.

  • 24.
    Yang, Jiayi
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Duan, Jiangjiang
    Wuhan University, China.
    Zhang, Lina
    Wuhan University, China.
    Lindman, Björn
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Edlund, Håkan
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Norgren, Magnus
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för kemiteknik.
    Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions2016Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 5, s. 3105-3115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel cellulose–chitosan nanocomposite particles with spherical shape were successfully prepared via mixing of aqueous biopolymer solutions in three different ways. Macroparticles with diameters in the millimeter range were produced by dripping cellulose dissolved in cold LiOH/urea into acidic chitosan solutions, inducing instant co-regeneration of the biopolymers. Two types of microspheres, chemically crosslinked and non-crosslinked, were prepared by first mixing cellulose and chitosan solutions obtained from freeze thawing in LiOH/KOH/urea. Thereafter epichlorohydrin was applied as crosslinking agent for one of the samples, followed by water-in-oil (W/O) emulsification, heat induced sol–gel transition, solvent exchange, washing and freeze-drying. Characterization by X-ray photoelectron spectroscopy, total elemental analysis, and Fourier transform infrared spectroscopy confirmed the prepared particles as being true cellulose–chitosan nanocomposites with different distribution of chitosan from the surface to the core of the particles depending on the preparation method. Field emission scanning electron microscopy and laser diffraction was performed to study the morphology and size distribution of the prepared particles. The morphology was found to vary due to different preparation routes, revealing a core shell structure for macroparticles prepared by dripping, and homogenous nanoporous structure for the microspheres. The non-crosslinked microparticles exhibited a somewhat denser structure than the crosslinked ones, which indicated that crosslinking restricts packing of the chains before and under regeneration. From the obtained volume-weighted size distributions it was found that the crosslinked microspheres had the highest median diameter. The results demonstrate that not only the mixing ratio and distribution of the two biopolymers, but also the morphology and nanocomposite particle diameters are tunable by choosing between the different routes of preparation.

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