| 1. |
- Degerstedt, Oliver, et al.
(författare)
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Quantitative imaging of doxorubicin diffusion and cellular uptake in biomimetic gels with human liver tumor cells
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Novel tumor-on-a-chip approaches are increasingly used to investigate tumor progression and potential treatment options. To improve the effect of any cancer treatment it is important to have an in-depth understanding of drug diffusion, penetration across the tumor extracellular matrix and cellular uptake. In this study, we have developed a miniaturized chip where drug diffusion and cellular uptake in different hydrogel environments can be quantified at high resolution using live imaging. Diffusion of doxorubicin was reduced in a biomimetic hydrogel mimicking tissue properties of cirrhotic liver and early stage hepatocellular carcinoma (362 ± 109 µm2/s) as compared to an agarose gel (571 ± 145 µm2/s, p = 0.0085). The diffusion was further lowered to 164 ± 33 µm2/s (p = 0.0023) by preparing the biomimetic gel in cell media instead of phosphate buffered saline. The addition of liver tumor cells (Huh7 or HepG2) to the gel, at two different densities, did not significantly influence drug diffusion. Clinically relevant and quantifiable doxorubicin concentration gradients (1-20 µM) were established in the chip within one hour. Intracellular increases in doxorubicin fluorescence correlated with decreasing fluorescence of the DNA-binding stain Hoechst 33342, and based on the quantified intracellular uptake of doxorubicin an apparent cell permeability (9.00 ± 0.74 x 10-4 µm/s for HepG2) was determined.
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| 2. |
- Andersson, Sara B. E., et al.
(författare)
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Effect of fluid velocity and particle size on the hydrodynamic diffusion layer thickness
- 2022
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier. - 0939-6411 .- 1873-3441. ; 180, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine the thickness of the hydrodynamic diffusion layer (h(HDL)) of three poor water-soluble compounds under laminar fluid flow using a single particle dissolution technique. The single particle dissolution experiments were performed in a flowing aqueous medium using four different fluid velocities (v), ranging from 46 to 103 mm/s. The particles used had an initial radius (r) of 18.8 to 52.3 mu m. The determined h(HDL) values were calculated from both dissolution experiments and computational fluid dynamics (CFD) simulation. In this study, single particle dissolution experiments gave, with one exception, h(HDL) values in the range of 2.09 to 8.85 mu m and corresponding simulations gave h(HDL) values in the range of 2.53 to 4.38 mu m. Hence, we found a semi-quantitative concordance between experimental and simulated determined h(HDL) values. Also, a theoretical relation between the dependence of hHDL on particle radius and flow velocity of the medium was established by a series of CFD simulations in a fluid velocity range of 10-100 mm/s and particle size (radius) range of 5-40 mu m. The outcome suggests a power law relation of the form h(HDL)alpha r(3/5)v(-2/5). In addition, the h(HDL) seems to be independent of the solubility, while it has a diffusion coefficient dependence. In conclusion, the hHDL values were determined under well-defined conditions; hence, this approach can be used to estimate the h(HDL) under different conditions to increase the understanding of the mass transfer mechanisms during the dissolution process.
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| 3. |
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| 4. |
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| 5. |
- Degerstedt, Oliver, et al.
(författare)
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Drug diffusion in biomimetic hydrogels : importance for drug transport and delivery in non-vascular tumor tissue
- 2022
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 172
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogels of varying complexity are routinely used as scaffolds and 3D structures for in vitro tumor models to increase physiological relevance within pre-clinical cancer research. Relatively simple hydrogels such as agarose are well characterised, meanwhile biomimetic gels containing collagen and fibrin(ogen) have been studied to a much lesser extent. In this study, hydrogels mimicking the biophysical characteristics of liver cancer progression were investigated in terms of their UV-properties and influence on diffusion coefficients of different substances. UV-imaging technology was used to both visualize and quantify the diffusion process in a simple and rapid way. In general, agarose gel diffusion agreed well with predictions using the Stokes-Einstein equation meanwhile the biomimetic gels reduced diffusion coefficients by up to 70%. For doxorubicin, spatio-temporal tissue concentration modelling was used to translate in vitro diffusion to the more clinical context of tumor penetration in a solid liver tumor supplied by arterial blood.
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| 6. |
- Edueng, Khadijah, et al.
(författare)
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Long-term physical (in)stability of spray-dried amorphous drugs: relationship with glass-forming ability and physicochemical properties
- 2019
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Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 11:9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This study shows the importance of the chosen method for assessing the glass-forming ability (GFA) and glass stability (GS) of a drug compound. Traditionally, GFA and GS are established using in situ melt-quenching in a differential scanning calorimeter. In this study, we included 26 structurally diverse glass-forming drugs (i) to compare the GFA class when the model drugs were produced by spray-drying with that when melt-quenching was used, (ii) to investigate the long-term physical stability of the resulting amorphous solids, and (iii) to investigate the relationship between physicochemical properties and the GFA of spray-dried solids and their long-term physical stability. The spray-dried solids were exposed to dry (<5% RH) and humid (75% RH) conditions for six months at 25 °C. The crystallization of the spray-dried solids under these conditions was monitored using a combination of solid-state characterization techniques including differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. The GFA/GS class assignment for 85% of the model compounds was method-dependent, with significant differences between spray-drying and melt-quenching methods. The long-term physical stability under dry condition of the compounds was predictable from GFA/GS classification and glass transition and crystallization temperatures. However, the stability upon storage at 75% RH could not be predicted from the same data. There was no strong correlation between the physicochemical properties explored and the GFA class or long-term physical stability. However, there was a slight tendency for compounds with a relatively larger molecular weight, higher glass transition temperature, higher crystallization temperature, higher melting point and higher reduced glass transition temperature to have better GFA and better physical stability. In contrast, a high heat of fusion and entropy of fusion seemed to have a negative impact on the GFA and physical stability of our dataset.
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| 7. |
- Edueng, Khadijah, et al.
(författare)
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Supersaturation Potential of Amorphous Active Pharmaceutical Ingredients after Long-Term Storage
- 2019
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 24:15
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Tidskriftsartikel (refereegranskat)abstract
- This study explores the effect of physical aging and/or crystallization on the supersaturation potential and crystallization kinetics of amorphous active pharmaceutical ingredients (APIs). Spray-dried, fully amorphous indapamide, metolazone, glibenclamide, hydrocortisone, hydrochlorothiazide, ketoconazole, and sulfathiazole were used as model APIs. The parameters used to assess the supersaturation potential and crystallization kinetics were the maximum supersaturation concentration (Cmax,app), the area under the curve (AUC), and the crystallization rate constant (k). These were compared for freshly spray-dried and aged/crystallized samples. Aged samples were stored at 75% relative humidity for 168 days (6 months) or until they were completely crystallized, whichever came first. The solid-state changes were monitored with differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. Supersaturation potential and crystallization kinetics were investigated using a tenfold supersaturation ratio compared to the thermodynamic solubility using the µDISS Profiler. The physically aged indapamide and metolazone and the minimally crystallized glibenclamide and hydrocortisone did not show significant differences in their Cmax,app and AUC when compared to the freshly spray-dried samples. Ketoconazole, with a crystalline content of 23%, reduced its Cmax,app and AUC by 50%, with Cmax,app being the same as the crystalline solubility. The AUC of aged metolazone, one of the two compounds that remained completely amorphous after storage, significantly improved as the crystallization kinetics significantly decreased. Glibenclamide improved the most in its supersaturation potential from amorphization. The study also revealed that, besides solid-state crystallization during storage, crystallization during dissolution and its corresponding pathway may significantly compromise the supersaturation potential of fully amorphous APIs.
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| 9. |
- Gråsjö, Johan, 1962-, et al.
(författare)
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Ion mobility and gel complex structure in dodecyl trimethylammonium/polyacrylate gel complexes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In the present study dielectric spectroscopy and small angle x-ray scattering were employed to evaluate temperature dependent ionic mobility and structural features in a dodecyltrimethylammonium/polyacrylate gel complex. A gradually transition of the gel complex from a structure exclusively consisting of discrete micelles arranged on a hexagonal close-packed lattice at 25 °C to a structure mainly consisting of a hexagonal phase of long rod-like micelles at ~ 65 °C was revealed. As well it was found that the mobility of the dodecyltrimethylammonium surfactant ions increased with an increasing fraction of hexagonal phase domains, something which was most likely due to a “residence time-hopping distance” mechanism of monomer ions moving between the micelles. The present findings should be useful for the understanding of the gel structure influence on the mechanisms for surfactant transport and shell formation in surfactant polyion gel complexes.
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| 10. |
- Gråsjö, Johan, 1962-
(författare)
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Molecular Arrangement, Electronic Structure and Transport Properties in Surfactant Gel- and Related Systems Studied by Soft X-ray and Dielectric Spectroscopy
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns studies of aqueous soft matter systems, especially surfactant micelle systems.The aim has been to study the molecular arrangement and electronic structure of the constituents of, as well as transport properties in such a system. The molecular arrangement and electronic structure has been studied by means of X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray spectroscopy (RIXS). The transport properties have been investigated by low-frequency dielectric spectroscopy (LFDS) and small angle X-ray scattering (SAXS) as well as a theoretical modelling. The latter was based on Fick’s laws of the release from binary surfactant system and was validated by experiments.The RIXS and XAS measurements show the electronic structure in bulk water and the influence of the chemical surrounding of the water molecule in bulk water and of the water molecules confined in a micelle lattice. The spectra are highly dependent on the molecular arrangement in such systems. For glycine and sodium polyacrylate RIXS and XAS spectra show features which are unique for carboxyl and carboxylate groups and such measurements can thus be used for fingerprinting.The LFDS and SAXS measurements show a strong correlation between structure in a surfactant/poly-ion system and apparent mobility of surfactants. This conclusion is in line with earlier observations.By the theoretical modelling a predictive model for the surfactant release from a binary surfactant micelle system has been obtained and the importance of different factors for surfactant release has been further clarified.
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