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Johansson, Emma
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Publications (10 of 20) Show all publications
Paul, B., Björk, E. M., Kumar, A., Lu, J. & Eklund, P. (2018). Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics. ACS applied energy materials, 1(5), 2261-2268
Open this publication in new window or tab >>Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics
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2018 (English)In: ACS applied energy materials, ISSN 2574-0962, Vol. 1, no 5, p. 2261-2268Article in journal (Refereed) Published
Abstract [en]

The development of high-performance and transferable thin-film thermoelectric materials is important for low-power applications, e.g., to power wearable electronics, and for on-chip cooling. Nanoporous films offer an opportunity to improve thermoelectric performance by selectively scattering phonons without affecting electronic transport. Here, we report the growth of nanoporous Ca3Co4O9 thin films by a sequential sputtering-annealing method. Ca3Co4O9 is promising for its high Seebeck coefficient and good electrical conductivity and important for its nontoxicity, low cost, and abundance of its constituent raw materials. To grow nanoporous films, multilayered CaO/CoO films were deposited on sapphire and mica substrates by rf-magnetron reactive sputtering from elemental Ca and Co targets, followed by annealing at 700 C to form the final phase of Ca3Co4O9. This phase transformation is accompanied by a volume contraction causing formation of nanopores in the film. The thermoelectric propoperties of the nanoporous Ca3Co4O9 films can be altered by controlling the porosity. The lowest electrical resistivity is ~7 mO cm, yielding a power factor of 2.32 × 10-4 Wm-1K-2 near room temperature. Furthermore, the films are transferable from the primary mica substrates to other arbitrary polymer platforms by simple dry transfer, which opens an opportunity of low-temperature use these materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
Ca3Co4O9; nanoporous; thermoelectrics; thin film; transferable
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-155845 (URN)10.1021/acsaem.8b00333 (DOI)000458705500058 ()29905306 (PubMedID)
Available from: 2019-03-29 Created: 2019-03-29 Last updated: 2019-04-04Bibliographically approved
Atakan, A., Mäkie, P., Söderlind, F., Keraudy, J., Johansson, E. & Odén, M. (2017). Synthesis of a Cu-infiltrated Zr-doped SBA-15 catalyst for CO2 hydrogenation into methanol and dimethyl ethert. Physical Chemistry, Chemical Physics - PCCP, 19(29), 19139-19149
Open this publication in new window or tab >>Synthesis of a Cu-infiltrated Zr-doped SBA-15 catalyst for CO2 hydrogenation into methanol and dimethyl ethert
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2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 29, p. 19139-19149Article in journal (Refereed) Published
Abstract [en]

A catalytically active nanoassembly comprising Cu-nanoparticles grown on integrated and active supports (large pore Zr-doped mesoporous SBA-15 silica) has been synthesized and used to promote CO2 hydrogenation. The doped mesoporous material was synthesized using a sal-gel method, in which the pore size was tuned between 11 and 15 nm while maintaining a specific surface area of about 700 m(2) g (1). The subsequent Cu nanoparticle growth was achieved by an infiltration process involving attachment of different functional groups on the external and internal surfaces of the mesoporous structure such that 7-10 nm sized Cu nanoparticles grew preferentially inside the pores. Chemisorption showed improved absorption of both CO2 and H-2 for the assembly compared to pure SBA-15 and 15% of the total CO2 was converted to methanol and dimethyl ether at 250 degrees C and 33 bar.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-139804 (URN)10.1039/c7cp03037a (DOI)000406334300033 ()28702581 (PubMedID)
Note

Funding Agencies|EUs Erasmus-Mundus program; Swedish Research Council; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 11 2009-00971]; Knut och Alice Wallenbergs Foundation [KAW 2012.0083]

Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2018-04-16
Sen Karaman, D., Sarwar, S., Desai, D., Björk, E., Odén, M., Chakrabarti, P., . . . Chakraborti, S. (2016). Shape engineering boosts antibacterial activity of chitosan coated mesoporous silica nanoparticle doped with silver: a mechanistic investigation. Journal of materials chemistry. B, 4(19), 3292-3304
Open this publication in new window or tab >>Shape engineering boosts antibacterial activity of chitosan coated mesoporous silica nanoparticle doped with silver: a mechanistic investigation
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2016 (English)In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 4, no 19, p. 3292-3304Article in journal (Refereed) Published
Abstract [en]

In this study, mesoporous silica nanoparticles (MSPs) of different size and shape were developed, and their surface coatings were utilized to study their differential effects in enhancing antibacterial activity. In brief, MSPs with three different aspect ratios (1, 2 and 4) were prepared, doped with silver ions and finally coated with the polymer chitosan. Both Gram-positive and Gram-negative bacteria were treated with the MSPs. Results indicate that silver ion doped and chitosan coated MSPs with the aspect ratio of 4 (Cht/MSP4:Ag+) have the highest antimicrobial activity among the prepared series. Further studies revealed that Cht/MSP4:Ag+ was most effective against Escherichia coli (E.coli) and least effective against Vibrio cholerae (V. cholerae). To investigate the detailed inhibition mechanism of the MSPs, the interaction of the nanoparticles with E.coli membranes and its intracellular DNA was assessed using various spectroscopic and imaging-based techniques. Furthermore, to increase the efficiency of the MSPs, a combinatorial antibacterial strategy was also explored, where nanoparticles, in combination with kanamycin (antibiotic), were used against Vibrio Cholerae (V. cholerae). Toxicity screening of these on MSPs was conducted on Caco-2 cells, and the results show that the dose used for antibacterial screening is below the limit of the toxicity threshold. Our findings show that both shape and surface engineering contribute positively towards killing bacteria, and the newly developed silver ion-doped and chitosan-coated MSPs have good potential as antimicrobial nanomaterials.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2016
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-129179 (URN)10.1039/c5tb02526e (DOI)000376039100014 ()
Note

Funding Agencies|CSIR, India; J. C. Bose national fellowship; Nanolith Sverige AB; Linnaeus environment Lili-NFM

Available from: 2016-06-13 Created: 2016-06-13 Last updated: 2017-11-28
Jeenpadiphat, S., Björk, E., Odén, M. & Nuntasri Tungasmita, D. (2015). Propylsulfonic acid functionalized mesoporous silica catalysts for esterification of fatty acids. Journal of Molecular Catalysis A: Chemical, 410, 253-259
Open this publication in new window or tab >>Propylsulfonic acid functionalized mesoporous silica catalysts for esterification of fatty acids
2015 (English)In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 410, p. 253-259Article in journal (Refereed) Published
Abstract [en]

The catalytic properties of 3 types of mesoporous silica SBA-15 (rope, rod and fiber), with 9.2 nm or 12.1 nm large mesopores, were examined with respect to their morphology and pore size. Commercially available Amberlyst-15 and the small pore sized MCM-41 were used for comparison. The catalysts were prepared by functionalization of the silica supports with propylsulfonic acid (Pr-SO3H) using postsynthesis grafting with 3 -mercaptopropyltrimethoxysilane as a propyl-thiol precursor. All materials remained in a well-ordered hexagonal mesoporous structure after Pr-SO3H functionalization. The performance of the Pr-SO3H-functionalized mesoporous silicas was evaluated in terms of their catalytic activity in the esterification of oleic acid with short (methanol) and long (glycerol) chain alcohols, i.e., to test the effect of the pore size on the substrate conversion and product yield. The synthesized catalysts were highly active and the product composition could be tuned by selective choice of the mesopore size. The Pr-SO3H-functionalized rope-shaped SBA-15 gave the highest catalytic activity (in terms of the highest methyl oleate and triglyceride yields and oleic acid conversion level), which was higher than that obtained with the commercial Amberlyst-15 catalyst. A high acid amount, large specific surface area and a suitable pore size are the likely reasons for the high yield gained by Pr-SO3H-functionalized rope-shaped SBA-15 silica. (C) 2015 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2015
Keywords
Mesoporous silica; Acid functionalization; Esterification; Fatty acid; Glycerol
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-123508 (URN)10.1016/j.molcata.2015.10.002 (DOI)000365368100030 ()
Note

Funding Agencies|Grant for International Research Integration: Chula Research Scholar, Ratchadaphiseksomphot Endowment Fund; Post-doctoral Fellowship (Ratchadaphiseksomphot Endowment Fund) Chulalongkorn University; Knut and Alice Wallenberg Foundation [KAW 2012.0083]; Nanolith Sverige AB

Available from: 2015-12-22 Created: 2015-12-21 Last updated: 2017-12-01
Senthilkumar, R., Sen Karaman, D., Paul, P., Johansson, E., Odén, M., Eriksson, J. E. & Rosenholm, J. M. (2015). Targeted delivery of a novel anticancer compound anisomelic acid using chitosan-coated porous silica nanorods for enhancing the apoptotic effect. BIOMATERIALS SCIENCE, 3(1), 103-111
Open this publication in new window or tab >>Targeted delivery of a novel anticancer compound anisomelic acid using chitosan-coated porous silica nanorods for enhancing the apoptotic effect
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2015 (English)In: BIOMATERIALS SCIENCE, ISSN 2047-4830, Vol. 3, no 1, p. 103-111Article in journal (Refereed) Published
Abstract [en]

Targeted cancer therapies are currently a strong focus in biomedical research. The most common approach is to use nanocarrier-based targeting to specifically deliver conventional anticancer drugs to enhance their therapeutic efficacy, increase bioavailability, and decrease the side-effects on normal cells. A step further towards higher specificity and efficacy would be to employ specific novel drugs along with specific nanocarrier-based targeting. Our recent studies have demonstrated that a plant-derived diterpenoid compound, anisomelic acid (AA), induces apoptosis in cervical cancer cells. In this work, we describe the development of a folic acid (FA)-targeted AA delivery system using chitosan-coated rod-shaped mesoporous silica particles (Chitosan-NR-MSP). The cellular internalization and uptake enhancement of the FA-Chitosan-NR-MSP towards cancerous folate receptor (FR)-positive (SiHa and HeLa) and/or normal FR-negative (HEK 293) cells were assessed, which indicated that the intracellular uptake of FA-conjugated Chitosan-NR-MSP was more target-specific. Furthermore, the induction of apoptosis by AA-loaded chitosan-coated rod-shaped particles on SiHa cells was studied. By employing caspase-3 activation and PARP cleavage as measure of apoptosis, the FA-particle mediated AA treatment was clearly more effective, significantly enhancing apoptosis in comparison to non-targeted Chitosan-NR-MSP or free AA in SiHa cells, suggesting that the FA-Chitosan-NR-MSPs can be potentially utilized as a drug delivery system for cervical cancer treatment.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-113162 (URN)10.1039/c4bm00278d (DOI)000345908400011 ()
Note

Funding Agencies|Sigrid Juselius Foundation; Center of Excellence for Functional Materials; Nanolith Sverige AB; Academy of Finland [140193, 260599, 278812]

Available from: 2015-01-14 Created: 2015-01-12 Last updated: 2015-01-29
Björk, E. M., Söderlind, F. & Odén, M. (2014). Single-pot synthesis of ordered mesoporous silica films with unique controllable morphology. Journal of Colloid and Interface Science, 413, 1-7
Open this publication in new window or tab >>Single-pot synthesis of ordered mesoporous silica films with unique controllable morphology
2014 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 413, p. 1-7Article in journal (Refereed) Published
Abstract [en]

Mesoporous silica films consisting of a monolayer of separated SBA-15 particles with unusually wide and short pores grown on silicon wafers have been fabricated in a simple single-pot-synthesis, and the formation of the films has been studied. A recipe for synthesizing mesoporous silica rods with the addition of heptane and NH4F at low temperature was used and substrates were added to the synthesis solution during the reaction. The films are ∼90 nm thick, have a pore size of 10.7–13.9 nm depending on the hydrothermal treatment time and temperature, and a pore length of 200–400 nm. All pores are parallel to the substrate, open, and easy to access, making them suitable for applications such as catalyst hosts and gas separation. The growth of the films is closely correlated to the evolution of the mesoporous silica particles. Here, we have studied the time for adding substrates to the synthesis solution, the evolution of the films with time during formation, and the effect of hydrothermal treatment. It was found that the substrates should be added within 30–60 s after turning off the stirring and the films are formed within 10 min after addition to the synthesis solution. The study has yielded a new route for synthesizing mesoporous silica films with a unique morphology.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
SBA-15; Mesoporous silica; Large pore; Films; Rods; Film growth; Particle formation
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-99856 (URN)10.1016/j.jcis.2013.09.023 (DOI)000327168800001 ()
Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2017-12-06Bibliographically approved
Björk, E. M., Söderlind, F. & Odén, M. (2013). Grafting mesoporous silica particles to substrates: a method for synthesizing mesoporous films with cylindrical pores perpendicular to the substrate.
Open this publication in new window or tab >>Grafting mesoporous silica particles to substrates: a method for synthesizing mesoporous films with cylindrical pores perpendicular to the substrate
2013 (English)Manuscript (preprint) (Other academic)
Abstract [en]

A method for synthesizing mesoporous silica films with cylindrical pores perpendicular to the substrate has been developed. The films consist of SBA-15 platelets that are grafted on glass substrates. The grafting is studied in terms of parameters such as pH, substrate functionalization, salt additions, time for TEOS prehydrolysis, and calcination. The best coverage of particles on the substrate was achieved for a low pH in combination with OTS-treated glass substrate. Furthermore, the prehydrolysis time of the TEOS was found to be a key parameter in order to bind the particles to the substrate. These porous films have potential in applications such as catalysis, drug delivery, and as a template for nanoparticle or nanorod, growth.

Keywords
Mesoporous silica films, platelets, particle functionalization, substrate functionalization, pH, salt
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-99857 (URN)
Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2013-10-22Bibliographically approved
Björk, E. M. (2013). Mesoporous Building Blocks: Synthesis and Characterization of Mesoporous Silica Particles and Films. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Mesoporous Building Blocks: Synthesis and Characterization of Mesoporous Silica Particles and Films
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Catalyst supports, drug delivery systems, hosts for nanoparticles, and solar cells are just some examples of the wide range of exciting applications for mesoporous silica. In order to optimize the performance of a specific application, controlling the material’s morphology and pore size is crucial. For example, short and separated particles are beneficial for drug delivery systems, while for molecular sieves, the pore size is the key parameter.

In this thesis, mesoporous silica building blocks, crystallites, with hexagonally ordered cylindrical pores were synthesized, with the aim to understand how the synthesis parameters affect the particle morphology and pore size. The synthesis of the particles is performed using a sol-gel process, and in order to increase the pore size, a combination of low temperature, and additions of heptane and NH4F was used. By variations in the amounts of reagents, as well as other synthesis conditions, the particle morphology and pore size could be altered. Separated particles were also grown on or attached to substrates to form films. Also, a material with spherical pore structure was synthesized, for the first time using this method.

It was found that a variation in the heptane concentration, in combination with a long stirring time, yields a transition between fiber and sheet morphologies. Both morphologies consist of crystallites, which for the fibers are joined end to end, while for the sheets they are attached side by side such that the pores are accessible from the sheet surface. The crystallites can be separated to a rod morphology by decreasing the stirring time and tuning the HCl concentration, and it was seen that these rods are formed within 5 min of static time, even though the pore size and unit cell parameters were evolving for another 30 min. Further studies of the effects of heptane showed that the shape and mesoscopic parameters of the rods are affected by the heptane concentration, up to a value where the micelles are fully saturated with heptane. It was also observed that the particle width increases with decreasing NH4F concentration, independent of heptane amount, and a platelet morphology can be formed. The formation time of the particles decrease with decreasing NH4F, and the growth mechanism for platelets was further studied. The pore sizes for various morphologies were altered by e.g. variations in the hydrothermal treatment conditions, or the method for removing the surfactants.

The separated particles can be attached to substrates, either during the particle synthesis or by post grafting prior to calcination. The film formation during the one-pot-synthesis was studied and a formation mechanism including nucleation of elongated micelles on the substrate was suggested. During the post grafting film synthesis, the medium in which the particles are dispersed, as well as functionalization of both particle and substrate are crucial for the post grafting process. The pores are easily accessible independent of the method, even though they are aligned parallel to the substrate when the one-pot-method is used, while post grafting gives a perpendicular pore orientation.

In summary, this work aims to give an understanding for the formation of the synthesized material, and how to tune the material properties by alterations in parameter space. Successful syntheses of four different particle morphologies and two new types of films were performed, and the pore size could easily be tuned by various methods.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. p. 82
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1542
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-99858 (URN)10.3384/diss.diva-99858 (DOI)978-91-7519-516-2 (ISBN)
Public defence
2013-11-15, Visionen, Hus B, Campus Valla, Linköpings universitet, Linköping, 13:15 (English)
Opponent
Supervisors
Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2019-12-03Bibliographically approved
Björk, E. M., Söderlind, F. & Odén, M. (2013). Tuning the shape of mesoporous silica particles by alterations in parameter space: from rods to platelets. Langmuir, 29(44), 13551-13561
Open this publication in new window or tab >>Tuning the shape of mesoporous silica particles by alterations in parameter space: from rods to platelets
2013 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 29, no 44, p. 13551-13561Article in journal (Refereed) Published
Abstract [en]

The knowledge of how to control the pore size and morphology of separated mesoporous silica particles is crucial for optimizing their performance in applications, such as molecular sieves and drug delivery systems. In this work, we have systematically studied the effects of various synthesis parameters to gain a deeper understanding of how particle morphologies can be altered. It was found that the morphology for isolated particles of SBA-15 type, with unusually short and wide pores, could be altered from rods to platelets by variations in the NH4F concentration. The pore length is nearly constant (similar to 300 nm) for the different morphologies, but the particle width is increasing from 200 nm to >3 mu m when decreasing the amount of NH4F, and the pore size can be tuned between 10 and 13 nm. Furthermore, other synthesis parameters such as heptane concentration, pH, silica precursor, and additions of ions have also been studied. The trend regarding particle width is independent of heptane concentration, at the same time as heptane increases the particle length up to a plateau value of similar to 500 nm. In all, parameters controlling particle width, length, and pore size have been separated in order to evaluate their function in the particle formation. Additionally, it was found that the formation time of the particles is strongly affected by the fluoride ion concentration, and a mechanism for particle formation for this system, where micelles transform from a foam, to multilamellar vesicles, and finally to cylindrical micelles, is suggested.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2013
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-99859 (URN)10.1021/la403201v (DOI)000326711200029 ()
Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2017-12-06Bibliographically approved
Gustafsson, H., Johannsson, E., Barrabino, A., Odén, M. & Holmberg, K. (2012). Immobilization of lipase from Mucor miehei and Rhizopus oryzae into mesoporous silica - The effect of varied particle size and morphology. Colloids and Surfaces B: Biointerfaces, 100, 22-30
Open this publication in new window or tab >>Immobilization of lipase from Mucor miehei and Rhizopus oryzae into mesoporous silica - The effect of varied particle size and morphology
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2012 (English)In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 100, p. 22-30Article in journal (Refereed) Published
Abstract [en]

Immobilization of enzymes usually improves the recyclability and stability and can sometimes also improve the activity compared to enzymes free in solution. Mesoporous silica is a widely studied material as host for immobilized enzymes because of its large internal surface area and tunable pores. It has previously been shown that the pore size is critical both for the loading capacity and for the enzymatic activity; however, less focus has been given to the influence of the particle size. In this work the effect of particle size and particle morphology on the immobilization of lipase from Mucor miehei and Rhizopus oryzae have been investigated. Three kinds of mesoporous silica, all with 9 nm pores but with varying particle size (1000 nm, 300 nm and 40 nm) have been synthesized and were used as host for the lipases. The two lipases, which have the same molecular size but widely different isoelectric points, were immobilized into the silica particles at varied pH values within the interval 5 to 8. The 300 nm particles were proven to be the most suitable carrier with respect to specific activity for both enzymes. The lipase from Mucor miehei was more than four times as active when immobilized at pH 8 compared to free in solution whereas the difference was less pronounced for the Rhizopus oryzae lipase.

Place, publisher, year, edition, pages
Elsevier, 2012
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:liu:diva-78683 (URN)10.1016/j.colsurfb.2012.04.042 (DOI)000307683900004 ()
Note

funding agencies|Nanolith Sverige AB||Swedish Research Council||

Available from: 2012-06-18 Created: 2012-06-18 Last updated: 2017-12-07
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