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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Karlsson, Christoffer, et al.
(författare)
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Stable Deep Doping of Vapor-Phase Polymerized Poly(3,4-ethylenedioxythiophene)/Ionic Liquid Supercapacitors.
- 2016
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 9:16, s. 2112-2121
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Tidskriftsartikel (refereegranskat)abstract
- Liquid-solution polymerization and vapor-phase polymerization (VPP) have been used to manufacture a series of chloride- and tosylate-doped poly(3,4-ethylenedioxythiophene) (PEDOT) carbon paper electrodes. The electrochemistry, specific capacitance, and specific charge were determined for single electrodes in 1-ethyl-3-methylimidazolium dicyanamide (emim dca) ionic liquid electrolyte. VPP-PEDOT exhibits outstanding properties with a specific capacitance higher than 300 F g(-1) , the highest value reported for a PEDOT-based conducting polymer, and doping levels as high as 0.7 charges per monomer were achieved. Furthermore, symmetric PEDOT supercapacitor cells with the emim dca electrolyte exhibited a high specific capacitance (76.4 F g(-1) ) and high specific energy (19.8 Wh kg(-1) ). A Ragone plot shows that the VPP-PEDOT cells combine the high specific power of conventional ("pure") capacitors with the high specific energy of batteries, a highly sought-after target for energy storage.
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| 6. |
- Keskinen, Jari, et al.
(författare)
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Asymmetric and symmetric supercapacitors based on polypyrrole and activated carbon electrodes
- 2015
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Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 203, s. 192-199
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Supercapacitors were prepared using either two polypyrrole (PPy) composite electrodes or one PPy composite and one activated carbon electrode. The PPy composite electrodes were either freestanding paper-like sheets or PPy films printed on graphite ink coated aluminium/PET laminate substrates, using Cladophora algae derived cellulose as the substrate or binder, respectively. The specific capacitance of the PPy electrodes was found to be about 200 F g−1 depending on the manufacturing method, yielding supercapacitors with capacitances between 0.45 and 3.8 F and energy efficiencies of over 90%. For an asymmetric device with activated carbon positive electrode and PPy negative electrode a capacitance loss of 5% was seen after 14300 cycles.
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| 8. |
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| 9. |
- Lilja, Mirjam, 1981-, et al.
(författare)
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Drug loading and release of Tobramycin from Hydroxyapatite coated fixation pins
- 2013
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Ingår i: Journal of materials science. Materials in medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 24:9, s. 2265-2274
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Tidskriftsartikel (refereegranskat)abstract
- This paper evaluates the loading and release properties of Tobramycin incorporated by adsorptive loading from a solution into plasma sprayed and biomimetically coated Hydroxyapatite (HA) fixation pins. The aim of this study is to contribute towards designing a functional implant surface offering local release of the antibiotic agent to prevent post-surgical infections. Cathodic arc deposition is used to coat stainless steel fixation pins with a bioactive, anatase phase dominated, TiO2 coating onto which a HA layer is grown biomimetically. The loading and release properties are evaluated by studying the subsequent release of Tobramycin using high performance liquid chromatography and correlated to the differences in HA coating microstructure and the physical conditions under loading. The results from these studies show that a dual loading strategy consisting of a solution temperature of 90 °C and a pressure of 6 bar during a loading time of 5 min release a sufficient amount of Tobramycin to guarantee the inhibition of Staphylococcus aureus up to 2 days for plasma sprayed HA coatings and for 8 days for biomimetic coatings. The present study emphasizes the advantages of the nanoporous structure of biomimetically deposited HA over the more dense structure of plasma sprayed HA coatings in terms of antibiotic incorporation and subsequent sustained release and provides a valuable outline for the design of implant surfaces aiming for a fast-loading and controlled, local drug administration.
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| 10. |
- Lilja, Mirjam, et al.
(författare)
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Effect of deposition parameters on the photocatalytic activity and bioactivity of TiO(2) thin films deposited by vacuum arc on Ti-6Al-4V substrates
- 2012
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 100B:4, s. 1078-1085
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Tidskriftsartikel (refereegranskat)abstract
- This article evaluates the influence of the main parameters in a cathodic arc deposition process on the microstructure of titanium dioxide thin coatings and correlates these to the photocatalytic activity (PCA) and in vitro bioactivity of the coatings. Bioactivity of all as deposited coatings was confirmed by the growth of uniform layers of hydroxyapatite (HA) after 7 days in phosphate buffered saline at 37°C. Comparison of the HA growth after 24 h indicated enhanced HA formation on coatings with small titanium dioxide grains of rutile and anatase phase. The results from the PCA studies showed that coatings containing a mixed microstructure of both anatase and rutile phases, with small grain sizes in the range of 26-30 nm and with a coating thickness of about 250 nm, exhibited enhanced activity as compared with other microstructures and higher coating thickness. The results of this study should be valuable for the development of new bioactive implant coatings with photocatalytically induced on-demand antibacterial properties.
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| 11. |
- Lilja, Mirjam, 1981-, et al.
(författare)
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Impact of Biomechanical Forces on Antibiotics Release Kinetics from Hydroxyapatite Coated Surgical Fixation Pins
- 2013
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Ingår i: Journal of Biomaterials and Nanobiotechnology. - : Scientific Research Publishing, Inc.. - 2158-7027 .- 2158-7043. ; 4:4, s. 343-350
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates the impact of biomechanical wear and abrasion on the antibiotic release profiles of hydroxyapa-tite (HA) coated fixation pins during their insertion into synthetic bone. Stainless steel fixation pins are coated with crystalline TiO2 by cathodic arc evaporation forming the bioactive layer for biomimetic deposition of Tobramycin con-taining HA. Tobramycin is either introduced by co-precipitation during HA formation or by adsorption-loading after HA deposition. The samples containing antibiotics are inserted into bone mimicking polyethylene foam after which the drug release is monitored using high performance liquid chromatography. This analysis shows that HA coating wear and delamination significantly decrease the amount of drug released during initial burst, but only marginally influence the sustained release period. Spalled coating fragments are found to remain within the synthetic bone material structure. The presence of HA within this structure supports the assumption that the local release of Tobramycin is not only ex-pected to eliminate bacteria growth directly at the pin interface but as well at some distance from the implant. Further-more, no negative effect of gamma sterilization could be observed on the drug release profile. Overall, the observed results demonstrate the feasibility of a multifunctional implant coating that is simultaneously able to locally deliver clinically relevant doses of antibiotics and an HA coating capable of promoting osteoconduction. This is a potentially promising step toward orthopaedic devices that combine good fixation with the ability to treat and prevent post-surgical infections.
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| 12. |
- Lilja, Mirjam, 1981-, et al.
(författare)
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Influence of microstructure and chemical composition of sputter deposited TiO2 thin films on in vitro bioactivity
- 2011
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Ingår i: Journal of materials science. Materials in medicine. - : Springer. - 0957-4530 .- 1573-4838. ; 22:12, s. 2727-2734
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Tidskriftsartikel (refereegranskat)abstract
- Functionalisation of biomedical implants viasurface modifications for tailored tissue response is agrowing field of research. Crystalline TiO2 has been provento be a bone bioactive, non-resorbable material. In contactwith body fluids a hydroxyapaptite (HA) layer forms on itssurface facilitating the bone contact. Thus, the path ofimproving biomedical implants via deposition of crystallineTiO2 on the surface is interesting to follow. In thisstudy we have evaluated the influence of microstructureand chemical composition of sputter deposited titaniumoxide thin films on the in vitro bioactivity. We find thatboth substrate bias, topography and the flow ratio of thegases used during sputtering affect the HA layer formed onthe films after immersion in simulated body fluid at 37C.A random distribution of anatase and rutile crystals, formedat negative substrate bias and low Ar to O2 gas flow ratios,are shown to favor the growth of flat HA crystal structureswhereas higher flow ratios and positive substrate biasinduced growth of more spherical HA structures. Thesefindings should provide valuable information when optimizingthe bioactivity of titanium oxide coatings as well asfor tailoring process parameters for sputtered-based productionof bioactive titanium oxide implant surfaces.
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| 13. |
- Lilja, Mirjam, 1981-, et al.
(författare)
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Photocatalytic and antimicrobial properties of surgical implant coatings of titanium dioxide deposited though cathodic arc evaporation
- 2012
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Ingår i: Biotechnology letters. - : Springer Science and Business Media LLC. - 0141-5492 .- 1573-6776. ; 41:6, s. 740-746
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured crystalline titaniumdioxide coatings deposited by cathodic arc evaporated on titanium grade five medical implant substrates were demonstrated to exhibit UV-induced photocatalytic activity that can be utilized to provide bactericidal effects against Staphylococcus epidermidis. The photocatalytic activity of the coatings was confirmedvia degradation of Rhodamine B under UV illumination.A 90 %reduction of viable bacteria was achieved in a clinically suitable time of only 2 min with a UVdose of 2.4 J delivered at 365 nm. These results areencouraging for the development of antimicrobialsurfaces in orthopedics and dentistry in order to prevent or treat post-surgical infections.
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| 14. |
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| 15. |
- Lilja, Mirjam, 1981-, et al.
(författare)
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Photocatalytic and bioactive TiO2 thin films deposited by vacuum arc
- 2012
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Ingår i: European Cells & Materials. - Aberystwyth : University of Wales. - 1473-2262. ; 23:Suppl. 5, s. 48-
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Tidskriftsartikel (refereegranskat)abstract
- Improving biomedical implants via deposition of functionalised surface coatings is a growing field of research. With respect to implant surfaces, infections present a major problem, and result mostly from the contamination of the surface by bacteria during surgery. UV irradiation induced photocatalysis on crystalline TiO2 implant surfaces may present a promising way to decontaminate surfaces while at the same time providing a bioactive surface for enhanced tissue integration.
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| 16. |
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| 17. |
- Pochard, Isabelle, et al.
(författare)
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Amine-functionalised mesoporous magnesium carbonate : Dielectric spectroscopy studies of interactions with water and stability
- 2018
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Ingår i: Materials Chemistry and Physics. - : ELSEVIER SCIENCE SA. - 0254-0584 .- 1879-3312. ; 216, s. 332-338
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Tidskriftsartikel (refereegranskat)abstract
- A mesoporous magnesium carbonate (MMC) material that was first described in 2013 is currently being investigated for several industrial and life-science-based applications. In this paper, the effect of functionalising the surface of MMC with amine groups on the water interaction properties of the material is investigated in detail. Amine functionalisation enhanced the stability and water sorption-release properties of the material. This is explained by the low affinity between amine-functionalised MMC and water molecules, as attested by the high free/total water ratio shown by dielectric spectroscopy. This low affinity had an impact on the total amount of adsorbed water at low relative humidities (RHs) but not at high RHs. The functionalisation of MMC with amine groups also stabilised the material in moist environments, hindering spontaneous crystallisation. These results provide a more fundamental understanding of the water interaction properties of MMC and are also expected to facilitate optimisation of the stability of materials like this for novel drug formulations and other life-science applications, as well as for their use in humidity control.
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| 18. |
- Rostedt Punga, Anna, et al.
(författare)
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Flodvåg av långtidssjuka covid-19-patienter väntar
- 2020
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Ingår i: Dagens Nyheter. - : Dagens Nyheter. - 1101-2447. ; , s. 5-5
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Hittills har sjukvård och forskning fokuserat på de som är svårt sjuka i covid-19. Samhällsspridningen i Sverige gör att även primärvården måste förbereda sig på ett stort antal patienter med komplexa och långdragna symtom. Nu publiceras en av de första vetenskapliga fallbeskrivningarna av en långtidssjuk patient, skriver forskare vid Uppsala universitet.
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| 19. |
- Sörensen, Jan Henrik, et al.
(författare)
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Biomechanical and Antibacterial Properties of Tobramycin Loaded Hydroxyapatite Coated Fixation Pins
- 2014
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 102:7, s. 1381-1392
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the use of nanoporous, biomimetic hydroxyapatite (HA) coatings deposited on TiO2 coated fixation pins as functional implant surfaces for the local release of Tobramycin in order to prevent bacterial colonization. The impact of HA-coating thickness, coating morphology and biomechanical forces during insertion into synthetic bone on the drug loading and release properties are analyzed. The coatings are shown to exhibit bactericidal effects against Staphylococcus aureus in agar medium for a duration of 6 days after loading by adsorption with Tobramycin for only 5 min at elevated temperature and pressure. Furthermore, high performance liquid chromatography analysis shows a drug release in phosphate buffered saline for 8 days with antibiotic concentration remaining above the minimal inhibitory concentration for S. aureus during the entire release period. Biomechanical insertion tests into synthetic bone and conventional scratch testing demonstrate adhesive strength at the HA/TiO2 interface. Biocompatibility is verified by cell viability tests. Outgrowth endothelial cells, as well as primary osteoblasts, are viable and firmly attached to both HA and TiO2 surfaces. The results presented are encouraging and support the concept of functional HA coatings as local drug delivery vehicles for biomedical applications to treat as well as to prevent post-surgical infections.
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| 20. |
- Sörensen, Jan H, et al.
(författare)
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Co-precipitation of Tobramycin into Biomimetically Coated Orthopedic Fixation Pins Employing Submicron-Thin Seed Layers of Hydroxyapatite
- 2014
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Ingår i: Current Drug Delivery. - : Bentham Science Publishers Ltd.. - 1567-2018 .- 1875-5704. ; 11:4, s. 501-510
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Tidskriftsartikel (refereegranskat)abstract
- Implant migration, loosening and cut-out as well as nosocomial infections are current problems during surgery. New innovative strategies to overcome these issues are emphasized in today's research. The currentwork presents a novel strategy involving co-precipitation ofTobramycin with biomimetic hydroxyapatite (HA) formation to produce implant coatings that may ensure controlled local drug delivery to prevent early bacterial colonization of the implant. A sub-micron thin HA layer served as seed layer for the co-precipitation process and allowed for incorporation of Tobramycin in the coating from a stock solution of antibiotic concentrations as high as 20 mg/ml. Concentrations from 0.5 to 20 mg/ml Tobramycin and process temperatures of 37 °C and 60 °C were tested to assess the optimal parameters resulting in a thin Tobramycin delivering HA coating on discs and orthopedic fixation pins. The coating morphology and thickness as well as drugrelease profile were evaluated via scanning electron microscopy and high performanceliquid chromatography. The coatings were found to deliver pharmaceutically relevant amounts of Tobramycinover a period as of12 days. To the best of our knowledge, this is the longest release period ever observed for a fast-loaded biomimetic implant coating. The presented approach may form thefoundation for development of combination device/antibiotic delivery vehicles tailored to meet well-defined clinical needs combatting infections and ensuring fast implant in-growth.
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| 21. |
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| 22. |
- Tammela, Petter, et al.
(författare)
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Asymmetric supercapacitors based on carbon nanofibre and polypyrrole/nanocellulose composite electrodes
- 2015
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Ingår i: RSC Advances. - 2046-2069. ; 5:21, s. 16405-16413
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Tidskriftsartikel (refereegranskat)abstract
- Asymmetric, all-organic supercapacitors (containing an aqueous electrolyte), exhibiting a capacitance of 25 F g-1 (or 2.3 F cm-2) at a current density of 20 mA cm-2 and a maximum cell voltage of 1.6 V, are presented. The devices contain a composite consisting of polypyrrole covered Cladophora cellulose fibres (PPy-cellulose) as the positive electrode while a carbon nanofibre material, obtained by heat treatment of the same PPy-cellulose composite under nitrogen gas flow, serves as the negative electrode. Scanning and transmission electron microscopy combined with X-ray photoelectron spectroscopy data show that the heat treatment gives rise to a porous carbon nanofibre material, topologically almost identical to the original PPy-cellulose composite. The specific gravimetric capacitances of the carbon and the PPy-cellulose electrodes were found to be 59 and 146 F g-1, respectively, while the asymmetric supercapacitors exhibited a gravimetric energy density of 33 J g-1. The latter value is about two times higher than the energy densities obtainable for a symmetric PPy-cellulose device as a result of the larger cell voltage range accessible. The capacitance obtained for the asymmetric devices at a current density of 156 mA cm-2 was 11 F g-1 and cycling stability results further indicate that the capacity loss was about 23% during 1000 cycles employing a current density of 20 mA cm-2. The present results represent a significant step forward towards the realization of all-organic material based supercapacitors with aqueous electrolytes and commercially viable capacitances and energy densities.
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| 23. |
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| 24. |
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| 25. |
- Vall, Maria, et al.
(författare)
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Amine-Modified Mesoporous Magnesium Carbonate as an Effective Adsorbent for Azo Dyes
- 2019
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:2, s. 2973-2979
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous magnesium carbonate (MMC) was evaluated as a potential candidate material for removal of dyes from textile industry wastewater. The adsorption property of MMC was analyzed for three different azo dyes: reactive black 5 (RB5), amaranth (AM), and acid red 183 (AR183). Further, the effect of porosity, amine modification, ionic strength, and pH was evaluated. MMC modified with 3-(aminopropyl)triethoxysilane (aMMC) showed consistently high uptake levels for all of the azo dyes tested; the uptake of RB5, AM, and AR183 was ∼360, ∼143 and ∼170 mg/g, respectively. The results demonstrated the importance of porosity and surface chemistry in the effective adsorption of the azo dye in aqueous systems. The uptake of RB5 and AM on aMMC was not significantly affected by pH (when varied between 4 and 10), although reduced uptake of RB5 and AM was observed at pH values <2 and >12. The addition of NaCl salt at concentrations up to 1000 mM had minimal effect on the high uptake of RB5 on aMMC. The uptake of AM by aMMC was reduced by approximately 20% in the presence of NaCl even at low concentrations. The uptake of AR183 by aMMC varied noticeably by changes in pH and no specific trend was observed. The presence of NaCl also adversely affected the uptake of AR183 on aMMC. The adsorption of the azo dye on aMMC was most likely driven by electrostatic interactions. We show here that aMMC is a potential candidate adsorbent for the effective removal of azo dyes from textile wastewaters.
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| 26. |
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| 27. |
- Vall, Maria, et al.
(författare)
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Carbon dioxide adsorption on mesoporous magnesium carbonate
- 2019
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Ingår i: Energy Procedia. - : Elsevier. - 1876-6102. ; 158, s. 4671-4676
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous magnesium carbonate (MMC) was synthesized and tested for its ability to separate CO2 from N2. The pure gas CO2 uptake of MMC was around 1.5 mmol/g at 101 kPa, 0 °C. The N2 uptake under the same conditions was less than 0.1 mmol/g. Al(NO3)3, Al2O3, K2CO3 and KNO3 were introduced into the porous structure of MMC as additives. All of the additives tested increased the CO2 uptake of MMC and increased its selectivity towards CO2. The incorporation of 5 wt.% K2CO3 increased the CO2 uptake of MMC up to over 3.2 mmol/g. The ideally adsorbed solution theory was used to calculate the CO2 selectivity of MMC and MMC with additives for a hypothetical gas mixture that contained 15% CO2: 85% N2. The CO2 selectivity at 101 kPa (0 °C) was around 60. MMC with 5 wt.% K2CO3 had a CO2 selectivity of over 150 under the same conditions. Vacuum swing cyclic CO2 adsorption/desorption showed that the CO2 uptake on MMC with 5 wt.% K2CO3 decreased after each cycle. Heat regeneration (up to 250 °C, for 10 minutes) could recover most of the lost CO2 capacity after each cycle. Heat regeneration indicatively improved the cyclic performance of this adsorbent. MMC with 5 wt.% K2CO3 was the best performing adsorbent in this study and can potentially be further developed into a good CO2 adsorbent for temperature swing adsorption (TSA) processes.
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| 28. |
- Vall, Maria
(författare)
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Development of Nanoporous Inorganic Carbonates for Pharmaceutical and Environmental Applications
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mesoporous magnesium carbonate (MMC) is a highly porous, anhydrous material which can be synthesized without the use of templates. This thesis shows how post- and in synthesis modification of MMC can create porous inorganic carbonates suitable for different pharmaceutical and environmental applications. Controlled release of IBU was achieved by loading IBU onto amine modified MMC (aMMC). The amine coverage was varied and there was a clear correlation between the release rate of IBU and the amine coverage, the higher the amine coverage the slower the release rate. aMMC was also used to load salicylic acid (SA). SA was then released within 15 minutes in a phosphate buffer (pH 6.8). The cytotoxicity of aMMC was evaluated and it was found non-toxic for human dermal fibroblast cells with particle concentration up to 1000 µg/mL for 48 h of exposure. aMMC also showed a high adsorption capacity for three different types of anionic azo dyes; acid red 183, amaranth and reactive black 5. The addition of amine groups to the surface of MMC significantly increased the uptake of the three dyes tested. Composite materials were synthesized by combining the synthesis of MMC and the synthesis of highly porous amorphous calcium carbonate. The calcium magnesium carbonate composite materials were evaluated for their CO2 sorption capacity (at 650 °C) and their CO2 cyclic stability. Addition of Al(NO3)3 to the best performing composite further improved its cyclic stability and the composite maintained a high CO2 uptake over 23 sorption/desorption cycles. Composite materials were also made by adding Al2O3 and SiO2 nanoparticles to the synthesis liquid of MMC. This resulted in materials with Al2O3 and SiO2 incorporated into the porous MMC structure. The MMC materials with Al2O3 and SiO2 nanoparticles was then impregnated with Ni(NO3)2, calcined and used for catalytic conversion of syngas to natural gas. The material containing Al2O3 nanoparticles performed the best and had a CO conversion of close to 100% at 350°C as well as a high CH4 yield and selectivity.In this thesis porous inorganic carbonates have been developed and evaluated for their performance in different pharmaceutical and environmental applications.
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| 29. |
- Vall, Maria, et al.
(författare)
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Effects of amine modification of mesoporous magnesium carbonate on controlled drug release
- 2017
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 524, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- (3-Aminopropyl)triethoxysilane (APTES) was used to modify the surface of mesoporous magnesium carbonate (MMC). The as-synthesized MMC had an average pore diameter of ∼5 nm, but amine grafting occurred preferentially on the walls of the largest MMC pores. Analysis of ibuprofen (IBU) loading and release showed that IBU remained stable in the amorphous phase in all the MMC and modified MMC samples. The kinetics of IBU release from the modified MMC were assessed and used to evaluate the effects of the different functional groups. The release rate showed that the release of IBU could be controlled by adjusting the amine surface coverage of MMC and also by changing the surface groups. It was concluded that the interaction between the grafted, functional groups in the modified MMC and the OH in the carboxyl groups of IBU was the most important factor for prolonging the release of the drug. These results are expected to lead to investigation of other as yet unexplored applications for MMC, including using it as a plastic additive and for gas separation.
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| 30. |
- Vall, Maria, et al.
(författare)
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Exploring the use of amine modified mesoporous magnesium carbonate for the delivery of salicylic acid in topical formulations: : in vitro cytotoxicity and drug release studies
- 2019
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Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 24:9
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Tidskriftsartikel (refereegranskat)abstract
- Salicylic acid (SA) has for a long time been used to treat various skin disorders due to its anti-inflammatory, bacteriostatic, and antifungal properties. In the present work, mesoporous magnesium carbonate (MMC), a promising drug carrier, was modified with 3-aminopropyl-triethoxysilane to enable loading of SA. The amine modified MMC (aMMC) was successfully loaded with 8 wt.% of SA via a solvent evaporation method. SA was later completely released from the carrier in less than 15 min. Furthermore, the cytotoxicity of the functionalized material was evaluated. aMMC was found to be non-toxic for human dermal fibroblast cells with particle concentration of up to 1000 µg/mL when exposed for 48 h. The presented results form the basis of future development of aMMC as a potential carrier for SA in dermatological applications.
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| 31. |
- Vall, Maria, et al.
(författare)
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Inorganic carbonate composites as potential high temperature CO2 sorbents with enhanced cycle stability
- 2019
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Ingår i: RSC Advances. - 2046-2069. ; 9:35, s. 20273-20280
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Tidskriftsartikel (refereegranskat)abstract
- A calcium magnesium carbonate composite (CMC) material containing highly porous amorphous calcium carbonate (HPACC) and mesoporous magnesium carbonate (MMC) was synthesized. CMCs with varying HPACC : MMC mol ratios and high BET surface area (over 490 m2 g−1) were produced. The CMCs retained the morphology shared by HPACC and MMC. All these materials were built up of aggregated nanometer-sized particles. We tested the CO2 uptake properties of the synthesized materials. The CMCs were calcined at 850 °C to obtain the corresponding calcium magnesium oxide composites (CMOs) that contained CaO : MgO at different mol ratios. CMO with CaO : MgO = 3 : 1 (CMO-3) showed comparable CO2 uptake at 650 °C (0.586 g g−1) to CaO sorbents obtained from pure HPACC (0.658 g g−1) and the commercial CaCO3 (0.562 g g−1). Over 23 adsorption–desorption cycles CMOs also showed a lower CO2 uptake capacity loss (35.7%) than CaO from HPACC (51.3%) and commercial CaCO3 (79.7%). Al was introduced to CMO by the addition of Al(NO3)3 in the synthesis of CMC-3 to give ACMO after calcination. The presence of ∼19 mol% of Al(NO3)3 in ACMO-4 significantly enhanced its stability over 23 cycles (capacity loss of 5.2%) when compared with CMO-3 (calcined CMC-3) without adversely affecting the CO2 uptake. After 100 cycles, ACMO-4 still had a CO2 uptake of 0.219 g g−1. Scanning electron microscope images clearly showed that the presence of Mg and Al in CMO hindered the sintering of CaCO3 at high temperatures and therefore, enhanced the cycle stability of the CMO sorbents. We tested the CO2 uptake properties of CMO and ACMO only under ideal laboratory testing environment, but our results indicated that these materials can be further optimized as good CO2 sorbents for various applications.
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| 32. |
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| 33. |
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| 34. |
- Welch, Ken, et al.
(författare)
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Bioactive and photocatalytically active surgical implant surfaces
- 2012
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Ingår i: Euro Bio-inspired Materials, International School and Conference on Biological Materials Science, 20-23 March.
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Konferensbidrag (refereegranskat)abstract
- Improving biomedical implants via deposition of functionalised surface coatings is a growing field of research. An enhanced bone-bonding capability by induction of hydroxyapatite (HA) formation on the implant surface is a critical characteristic of a bioactive implant coating. In the field of implants, infections present a major problem, and result mostly from the contamination of the implant surface by bacteria during surgery. There is a need for antibacterial surface treatments, which can prevent the bacterial colonization and biofilm formation without compromising the biocompatibility of the implant itself.Crystalline TiO2 is not only a bioactive, non-resorbable material, it also exhibits excellent superhydrophilic and photocatalytic properties when irradiated with UV light. Thus, UV irradiation induced photocatalysis on crystalline TiO2 implant surfaces may present an effective method for decontaminating implant surfaces.In our study we have evaluated the influence of the main deposition parameters in the cathodic evaporation process on the microstructure of TiO2 thin films and correlated these to the photocatalytic activity (PCA) and in vitro bioactivity of the coatings.Bioactivity of all as deposited coatings was confirmed by the growth of uniform layers of HA after 7 days in phosphate buffered saline at 37 °C. Comparison of the HA growth after 24 hours indicated enhanced HA formation on coatings with small titanium dioxide grains of the rutile and the anatase phase. The results from the PCA studies showed that coatings containing a mixed microstructure of both anatase and rutile phases, with small grain sizes in the range of 26-30 nm and with a coating thickness of about 250 nm, exhibited enhanced activity as compared to other microstructures and higher coating thickness. The results of this study should be valuable for the development of new bioactive implant coatings with photocatalytically induced on-demand antibacterial properties.
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| 35. |
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| 36. |
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| 37. |
- Afewerki, Samson, et al.
(författare)
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Combined Catalysis for Engineering Bioinspired, Lignin-Based, Long-Lasting, Adhesive, Self-Mending, Antimicrobial Hydrogels
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 14:12, s. 17004-17017
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Tidskriftsartikel (refereegranskat)abstract
- The engineering of multifunctional biomaterials using a facile sustainable methodology that follows the principles of green chemistry is still largely unexplored but would be very beneficial to the world. Here, the employment of catalytic reactions in combination with biomass-derived starting materials in the design of biomaterials would promote the development of eco-friendly technologies and sustainable materials. Herein, we disclose the combination of two catalytic cycles (combined catalysis) comprising oxidative decarboxylation and quinone-catechol redox catalysis for engineering lignin-based multifunctional antimicrobial hydrogels. The bioinspired design mimics the catechol chemistry employed by marine mussels in nature. The resultant multifunctional sustainable hydrogels (1) are robust and elastic, (2) have strong antimicrobial activity, (3) are adhesive to skin tissue and various other surfaces, and (4) are able to self-mend. A systematic characterization was carried out to fully elucidate and understand the facile and efficient catalytic strategy and the subsequent multifunctional materials. Electron paramagnetic resonance analysis confirmed the long-lasting quinone-catechol redox environment within the hydrogel system. Initial in vitro biocompatibility studies demonstrated the low toxicity of the hydrogels. This proof-of-concept strategy could be developed into an important technological platform for the eco-friendly, bioinspired design of other multifunctional hydrogels and their use in various biomedical and flexible electronic applications.
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| 38. |
- Afewerki, Samson, 1985-, et al.
(författare)
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In vitro high-content tissue models to address precision medicine challenges
- 2023
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Ingår i: Molecular Aspects of Medicine. - : Elsevier. - 0098-2997 .- 1872-9452. ; 91
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Tidskriftsartikel (refereegranskat)abstract
- The field of precision medicine allows for tailor-made treatments specific to a patient and thereby improve the efficiency and accuracy of disease prevention, diagnosis, and treatment and at the same time would reduce the cost, redundant treatment, and side effects of current treatments. Here, the combination of organ-on-a-chip and bioprinting into engineering high-content in vitro tissue models is envisioned to address some precision medicine challenges. This strategy could be employed to tackle the current coronavirus disease 2019 (COVID-19), which has made a significant impact and paradigm shift in our society. Nevertheless, despite that vaccines against COVID-19 have been successfully developed and vaccination programs are already being deployed worldwide, it will likely require some time before it is available to everyone. Furthermore, there are still some uncertainties and lack of a full understanding of the virus as demonstrated in the high number new mutations arising worldwide and reinfections of already vaccinated individuals. To this end, efficient diagnostic tools and treatments are still urgently needed. In this context, the convergence of bioprinting and organ-on-a-chip technologies, either used alone or in combination, could possibly function as a prominent tool in addressing the current pandemic. This could enable facile advances of important tools, diagnostics, and better physiologically representative in vitro models specific to individuals allowing for faster and more accurate screening of therapeutics evaluating their efficacy and toxicity. This review will cover such technological advances and highlight what is needed for the field to mature for tackling the various needs for current and future pandemics as well as their relevancy towards precision medicine.
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| 39. |
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| 40. |
- Ahrentorp, Fredrik, et al.
(författare)
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Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils
- 2017
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 427, s. 14-18
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Tidskriftsartikel (refereegranskat)abstract
- We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 mu m. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 mu L) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.
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| 41. |
- Akhtar, Sultan, et al.
(författare)
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Real-Space Transmission Electron Microscopy Investigations of Attachment of Functionalized Magnetic Nanoparticles to DNA-Coils Acting as a Biosensor
- 2010
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 114:41, s. 13255-13262
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Tidskriftsartikel (refereegranskat)abstract
- The present work provides the first real-space analysis of nanobead-DNA coil interactions. Immobilization of oligonucleotide-functionalized magnetic nanobeads in rolling circle amplified DNA-coils was studied by complex magnetization measurements and transmission electron microscopy (TEM), and a statistical analysis of the number of beads hybridized to the DNA-coils was performed. The average number of beads per DNAcoil using the results from both methods was found to be around 6 and slightly above 2 for samples with 40 and 130 nm beads, respectively. The TEM analysis supported an earlier hypothesis that 40 nm beads are preferably immobilized in the interior of DNA-coils whereas 130 nm beads, to a larger extent, are immobilized closer to the exterior of the coils. The methodology demonstrated in the present work should open up new possibilities for characterization of interactions of a large variety of functionalized nanoparticles with macromolecules, useful for gaining more fundamental understanding of such interactions as well as for optimizing a number of biosensor applications.
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| 42. |
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| 43. |
- Akhtar, Sultan, et al.
(författare)
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Visualization of functionalization of nano-particles and graphene in the TEM
- 2010
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Ingår i: Advanced Materials Workshop 2010.
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Konferensbidrag (refereegranskat)abstract
- Recently, the activity on functionalized nano-objects has strongly increased. Yet, there are, to our knowledge no techniques available that visualize the attachment of molecules to nano-entities such as nanoparticles and graphene. In this work, we show a methodology to analyse the attachment of molecules to nanoparticles and graphene. The difficulty of such transmission electron microscopy (TEM) characterization consists in the high beam sensitivity of these nanoobjects. We employed a high resolution- as well as diffraction contrast-imaging methods to characterize graphene. First, we have developed a method to measure the thickness of free-standing graphene-like layers. The refinement of these imaging techniques enabled the imaging of functionalized C60 (fullerene) on top of a few-layer graphene flake by TEM. We also developed a methodology to visualize the attachment of functionalized gold and magnetic nanoparticles (different sizes) to nonstained and unlabeled single strand DNA-coils. This technique can be used to understand the interaction of a large variety of functionalized nanoparticles with their solution environment and/or macromolecular structures for their large applications.
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| 44. |
- Alvebratt, Caroline, et al.
(författare)
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A Modified In Situ Method to Determine Release from a Complex Drug Carrier in Particle-Rich Suspensions
- 2018
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Ingår i: AAPS PharmSciTech. - : Springer Science and Business Media LLC. - 1530-9932. ; 19:7, s. 2859-2865
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Tidskriftsartikel (refereegranskat)abstract
- Effective and compound-sparing methods to evaluate promising drug delivery systems are a prerequisite for successful selection of formulations in early development stages. The aim of the study was to develop a small-scale in situ method to determine drug release and supersaturation in highly concentrated suspensions of enabling formulations. Mesoporous magnesium carbonate (MMC), which delivers the drug in an amorphous form, was selected as a drug carrier. Five model compounds were loaded into the MMC at a 1:10 ratio using a solvent evaporation technique. The μDiss Profiler was used to study the drug release from MMC in fasted-state simulated intestinal fluid. To avoid extensive light scattering previously seen in particle-rich suspensions in the μDiss Profiler, an in-house-designed protective nylon filter was placed on the in situ UV probes. Three types of release experiments were conducted for each compound: micronized crystalline drug with MMC present, drug-loaded MMC, and drug-loaded MMC with 0.01% w/w hydroxypropyl methyl cellulose. The nylon filters effectively diminished interference with the UV absorption; however, the release profiles obtained were heavily compound dependent. For one of the compounds, changes in the UV spectra were detected during the release from the MMC, and these were consistent with degradation of the compound. To conclude, the addition of protective nylon filters to the probes of the μDiss Profiler is a useful contribution to the method, making evaluations of particle-rich suspensions feasible. The method is a valuable addition to the current ones, allowing for fast and effective evaluation of advanced drug delivery systems.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Alvebratt, Caroline
(författare)
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Advanced Methods for Evaluation of the Performance of Complex Drug Delivery System
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Low oral bioavailability of drugs originating from poor aqueous solubility is a common issue in drug development. Various enabling formulations have been presented to circumvent this limitation, many making use of supersaturation. In these, the drug is delivered to the gastro-intestinal lumen in a high energy state e.g. in amorphous form or a liquid lipid vehicle. Concentrations surpassing the equilibrium solubility of the crystalline drug are achieved, which facilitate increased absorption for dissolution-rate limited compounds. Meanwhile the use of the enabling formulation can be beneficial to increase the bioavailability of poorly water-soluble drugs, in vitro evaluation of these systems remain challenging. Limited methods have also evaluated several different types of enabling formulation in the same experimental setup. The overall aim of this thesis was therefore to develop assays to study the performance of various complex drug delivery systems. In the first part, a small scale dissolution apparatus, the µDiss Profiler, was used to study drug release from drug-loaded mesoporous magnesium carbonate (MMC). A protective filter was developed to minimize particle interference on the UV-measurements, enabling studies of supersaturation from the amorphous carrier. In the second paper, lipids were adsorbed onto the MMC. A modified in vitro lipolysis setup was established and the samples were analyzed with nuclear magnetic resonance spectroscopy. A stability study of the lipid-loaded MMC was also performed. The methods developed in the first two projects provided an insight to events occurring in the intestinal lumen. The intestinal absorption has however been shown to be a complex interplay between dissolution-digestion and permeation. In the final two projects, two devices comprising of a donor (luminal) chamber and a receiver (serosal) chamber were studied (the µFLUX and the enabling absorption, ENA, device). The two chambers were separated by a semipermeable membrane (cell-based and/or phospholipid-based). A wide range of enabling formulations were evaluated in the two assays. As the exposure in the donor correlated poorly with the exposure in the receiver compartment, this emphasizes the importance of in vitro methods taking both the dissolution-digestion and permeation into account. The ENA results also predicted the in vivo performance in rats well. To conclude, several models have been established in the thesis to study the in vitro performance of enabling formulations, which will be valuable for screening of appropriate drug delivery systems.
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| 49. |
- Alvebratt, Caroline, et al.
(författare)
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An in vitro dissolution–digestion–permeation assay for the study of advanced drug delivery systems
- 2020
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 149, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- Advanced drug delivery systems (ADDS) are widely explored to overcome poor aqueous solubility of orally administered drugs. However, the prediction of their in vivo performance is challenging, as in vitro models typically do not capture the interplay between processes occurring in the gut. In additions, different models are used to evaluate the different systems. We therefore present a method that allows monitoring of luminal processing (dissolution, digestion) and its interplay with permeation to better inform on the absorption of felodipine formulated as ADDS. Experiments were performed in a µFLUX-apparatus, consisting of two chambers, representing the intestinal and serosal compartment, separated by Caco-2 monolayers. During dissolution–digestion–permeation experiments, ADDS were added to the donor compartment containing simulated intestinal fluid and immobilized lipase. Dissolution and permeation in both compartments were monitored using in situ UV-probes or, when turbidity interfered the measurements, with HPLC analysis.The method showed that all ADDS increased donor and receiver concentrations compared to the condition using crystalline felodipine. A poor correlation between the compartments indicated the need for an serosal compartment to evaluate drug absorption from ADDS. The method enables medium-throughput assessment of: (i) dynamic processes occurring in the small intestine, and (ii) drug concentrations in real-time.
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| 50. |
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