| 1. |
- Thul, Peter J., et al.
(författare)
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A subcellular map of the human proteome
- 2017
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 356:6340
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Tidskriftsartikel (refereegranskat)abstract
- Resolving the spatial distribution of the human proteome at a subcellular level can greatly increase our understanding of human biology and disease. Here we present a comprehensive image-based map of subcellular protein distribution, the Cell Atlas, built by integrating transcriptomics and antibody-based immunofluorescence microscopy with validation by mass spectrometry. Mapping the in situ localization of 12,003 human proteins at a single-cell level to 30 subcellular structures enabled the definition of the proteomes of 13 major organelles. Exploration of the proteomes revealed single-cell variations in abundance or spatial distribution and localization of about half of the proteins to multiple compartments. This subcellular map can be used to refine existing protein-protein interaction networks and provides an important resource to deconvolute the highly complex architecture of the human cell.
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| 2. |
- Nawaz, Saima, et al.
(författare)
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Polyaniline inside the pores of high surface area mesoporous silicon as composite electrode material for supercapacitors
- 2022
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Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 12:27, s. 17228-17236
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous silicon (mSi) obtained by the magnesiothermic reduction of mesoporous silica was used to deposit polyaniline (PANI) in its pores, the composite was tested for its charge storage application for high performance supercapacitor electrodes. The mesoporous silica as confirmed by Small Angle X-ray Scattering (SAXS) has a Brunauer-Emmett-Teller (BET) surface area of 724 m(2)g(-1) and mean pore size of 5 nm. After magnesiothermic reduction to mSi, the BET surface area is reduced to 348 m(2)g(-1) but the mesoporousity is retained with a mean pore size of 10 nm. The BET surface area of mesoporous silicon is among the highest for porous silicon prepared/reduced from silica. In situ polymerization of PANI inside the pores of mSi was achieved by controlling the polymerization conditions. As a supercapacitor electrode, the mSi-PANI composite exhibits better charge storage performance as compared to pure PANI and mesoporous silica-PANI composite electrodes. Enhanced electrochemical performance of the mSi-PANI composite is attributed to the high surface mesoporous morphology of mSi with a network structure containing abundant mesopores enwrapped by an electrochemically permeable polyaniline matrix.
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| 3. |
- Björk, Emma M., et al.
(författare)
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Grafting mesoporous silica particles to substrates : a method for synthesizing mesoporous films with cylindrical pores perpendicular to the substrate
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 4. |
- Björk, Emma M., 1981-
(författare)
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Mesoporous Building Blocks : Synthesis and Characterization of Mesoporous Silica Particles and Films
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 5. |
- Björk, Emma M., et al.
(författare)
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Single-pot synthesis of ordered mesoporous silica films with unique controllable morphology
- 2014
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 413, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Björk, Emma M., et al.
(författare)
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Tuning the shape of mesoporous silica particles by alterations in parameter space : from rods to platelets
- 2013
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 29:44, s. 13551-13561
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Björk, Emma, et al.
(författare)
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Mesoporous silica and carbon based catalysts for esterification and biodiesel fabrication-The effect of matrix surface composition and porosity
- 2017
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Ingår i: Applied Catalysis A. - : ELSEVIER SCIENCE BV. - 0926-860X .- 1873-3875. ; 533, s. 49-58
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Tidskriftsartikel (refereegranskat)abstract
- The effects of catalyst matrix porosity composition on the catalytic performance have been studied using sulfonated mesoporous SBA-15 silica. The matrix was sulfonated with three different methods grafting, in situ oxidation, and carbon infiltration. Additionally, unordered sulfonated mesoporous carbon, and the commercial catalysts Amberlite IR-120 and Nafion 117 were tested. The catalytic performance was evaluated in a Fischer esterification using acetic acid and ethanol, as well as in a transesterification of triglycerides (sunflower oil) and ethanol to produce biodiesel. The study shows that for long carbon chains, the effective wetting of the porous catalyst matrix by the reactants is most important for the catalytic efficiency, while for shorter carbon chain, the mass transport of the reagents trough the porous structure is more important. The catalysts were analysed using electron microscopy and physisorption. The study shows that the reactions are faster with carbon infiltrated materials than the silica materials due to a higher concentration of sulfonic groups linked to the carbon. The in situ functionalized SBA-15 is a more efficient catalyst compared to the post grafted one. All the synthesized catalysts outperform the commercial ones in both reactions in terms of conversion. (C) 2017 Elsevier B.V. All rights reserved.
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| 8. |
- Paul, Biplab, 1980-, et al.
(författare)
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Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics
- 2018
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:5, s. 2261-2268
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Sen Karaman, D., et al.
(författare)
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Shape engineering boosts antibacterial activity of chitosan coated mesoporous silica nanoparticle doped with silver: a mechanistic investigation
- 2016
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Ingår i: Journal of materials chemistry. B. - : ROYAL SOC CHEMISTRY. - 2050-750X .- 2050-7518. ; 4:19, s. 3292-3304
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Säll, Johanna, et al.
(författare)
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Salt-inducible kinase 2 and -3 are downregulated in adipose tissue from obese or insulin-resistant individuals : implications for insulin signalling and glucose uptake in human adipocytes
- 2017
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 60:2, s. 314-323
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: Salt-inducible kinases (SIKs) are related to the metabolic regulator AMP-activated protein kinase (AMPK). SIK2 is abundant in adipose tissue. The aims of this study were to investigate the expression of SIKs in relation to human obesity and insulin resistance, and to evaluate whether changes in the expression of SIKs might play a causal role in the development of disturbed glucose uptake in human adipocytes.METHODS: SIK mRNA and protein was determined in human adipose tissue or adipocytes, and correlated to clinical variables. SIK2 and SIK3 expression and phosphorylation were analysed in adipocytes treated with TNF-α. Glucose uptake, GLUT protein levels and localisation, phosphorylation of protein kinase B (PKB/Akt) and the SIK substrate histone deacetylase 4 (HDAC4) were analysed after the SIKs had been silenced using small interfering RNA (siRNA) or inhibited using a pan-SIK-inhibitor (HG-9-91-01).RESULTS: We demonstrate that SIK2 and SIK3 mRNA are downregulated in adipose tissue from obese individuals and that the expression is regulated by weight change. SIK2 is also negatively associated with in vivo insulin resistance (HOMA-IR), independently of BMI and age. Moreover, SIK2 protein levels and specific kinase activity display a negative correlation to BMI in human adipocytes. Furthermore, SIK2 and SIK3 are downregulated by TNF-α in adipocytes. Silencing or inhibiting SIK1-3 in adipocytes results in reduced phosphorylation of HDAC4 and PKB/Akt, less GLUT4 at the plasma membrane, and lower basal and insulin-stimulated glucose uptake in adipocytes.CONCLUSION/INTERPRETATION: This is the first study to describe the expression and function of SIKs in human adipocytes. Our data suggest that SIKs might be protective in the development of obesity-induced insulin resistance, with implications for future treatment strategies.
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