| 1. |
- Hossain, Shakhawath, et al.
(författare)
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Influence of Bile Composition on Membrane Incorporation of Transient Permeability Enhancers
- 2020
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8392 .- 1543-8384. ; 17:11, s. 4226-4240
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Tidskriftsartikel (refereegranskat)abstract
- Transient permeability enhancers (PEs), such as caprylate, caprate, and salcaprozate sodium (SNAC), improve the bioavailability of poorly permeable macromolecular drugs. However, the effects are variable across individuals and classes of macromolecular drugs and biologics. Here, we examined the influence of bile compositions on the ability of membrane incorporation of three transient PEs-caprylate, caprate, and SNAC-using coarse-grained molecular dynamics (CG-MD). The availability of free PE monomers, which are important near the absorption site, to become incorporated into the membrane was higher in fasted-state fluids than that in fed-state fluids. The simulations also showed that transmembrane perturbation, i.e., insertion of PEs into the membrane, is a key mechanism by which caprylate and caprate increase permeability. In contrast, SNAC was mainly adsorbed onto the membrane surface, indicating a different mode of action. Membrane incorporation of caprylate and caprate was also influenced by bile composition, with more incorporation into fasted- than fed-state fluids. The simulations of transient PE interaction with membranes were further evaluated using two experimental techniques: the quartz crystal microbalance with dissipation technique and total internal reflection fluorescence microscopy. The experimental results were in good agreement with the computational simulations. Finally, the kinetics of membrane insertion was studied with CG-MD. Variation in micelle composition affected the insertion rates of caprate monomer insertion and expulsion from the micelle surface. In conclusion, this study suggests that the bile composition and the luminal composition of the intestinal fluid are important factors contributing to the interindividual variability in the absorption of macromolecular drugs administered with transient PEs.
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| 2. |
- Jõemetsa, Silver, 1990, et al.
(författare)
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Independent Size and Fluorescence Emission Determination of Individual Biological Nanoparticles Reveals that Lipophilic Dye Incorporation Does Not Scale with Particle Size
- 2020
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 36:33, s. 9693-9700
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Tidskriftsartikel (refereegranskat)abstract
- Advancements in nanoparticle characterization techniques are critical for improving the understanding of how biological nanoparticles (BNPs) contribute to different cellular processes, such as cellular communication, viral infection, as well as various drug-delivery applications. Since BNPs are intrinsically heterogeneous, there is a need for characterization methods that are capable of providing information about multiple parameters simultaneously, preferably at the single-nanoparticle level. In this work, fluorescence microscopy was combined with surface-based two-dimensional flow nanometry, allowing for simultaneous and independent determination of size and fluorescence emission of individual BNPs. In this way, the dependence of the fluorescence emission of the commonly used self-inserting lipophilic dye 3,3′-dioctadecyl-5,5′-di(4-sulfophenyl)oxacarbocyanine (SP-DiO) could successfully be correlated with nanoparticle size for different types of BNPs, including synthetic lipid vesicles, lipid vesicles derived from cellular membrane extracts, and extracellular vesicles derived from human SH-SY5Y cell cultures; all vesicles had a radius, r, of ∼50 nm and similar size distributions. The results demonstrate that the dependence of fluorescence emission of SP-DiO on nanoparticle size varies significantly between the different types of BNPs, with the expected dependence on membrane area, r2, being observed for synthetic lipid vesicles, while a significant weaker dependence on size was observed for BNPs with more complex composition. The latter observation is attributed to a size-dependent difference in membrane composition, which may influence either the optical properties of the dye and/or the insertion efficiency, indicating that the fluorescence emission of this type of self-inserting dye may not be reliable for determining size or size distribution of BNPs with complex lipid compositions.
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| 3. |
- Jõemetsa, Silver, 1990, et al.
(författare)
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Molecular Lipid Films on Microengineering Materials
- 2019
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 35:32, s. 10286-10298
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we have systematically investigated the formation of molecular phospholipid films on a variety of solid substrates fabricated from typical surface engineering materials and the fluidic properties of the lipid membranes formed on these substrates. The surface materials comprise of borosilicate glass, mica, SiO2, Al (native oxide), Al2O3, TiO2, ITO, SiC, Au, Teflon AF, SU-8, and graphene. We deposited the lipid films from small unilamellar vesicles (SUVs) by means of an open-space microfluidic device, observed the formation and development of the films by laser scanning confocal microscopy, and evaluated the mode and degree of coverage, fluidity, and integrity. In addition to previously established mechanisms of lipid membrane–surface interaction upon bulk addition of SUVs on solid supports, we observed nontrivial lipid adhesion phenomena, including reverse rolling of spreading bilayers, spontaneous nucleation and growth of multilamellar vesicles, and the formation of intact circular patches of double lipid bilayer membranes. Our findings allow for accurate prediction of membrane–surface interactions in microfabricated devices and experimental environments where model membranes are used as functional biomimetic coatings.
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| 4. |
- Jõemetsa, Silver, 1990
(författare)
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Supported Lipid Membranes and Their Use for the Characterization of Biological Nanoparticles
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biological nanoparticles (BNPs) are nano-sized lipid vesicles of biological origin, which are involved in multiple biological processes. BNP characterization techniques are critical for improving the understanding of how these particles contribute to cellular communication, viral infections and drug-delivery applications. However, due to their small size (between 50 and 200 nm in diameter) and molecular heterogeneity, quantitative characterization of their physical, chemical and biological properties is demanding, especially since their large structural and compositional heterogeneity calls for methods with single nanoparticle resolution. To address this challenge, work in this thesis has been focused on investigating and using supported lipid bilayers (SLBs) and their two-dimensional fluidity as a platform for nanoparticle characterization. To investigate SLBs, we combined confocal microscopy with microfluidics to identify the mechanisms by which lipid vesicles are spontaneously converted into various types of planar membranes on a multitude of surfaces (Paper I) and found that most of the studied materials can support lipid film formation. In the context of SLB formation, specific focus was put on using total internal reflection fluorescence (TIRF) microscopy to monitor the kinetics of vesicle adsorption, rupture and spreading of individual SLB patches on glass (Paper II), revealing that the SLB formation process was driven by the autocatalytic growth and merger of multiple small SLB patches at appreciably high vesicle coverage. TIRF was also successfully employed to monitor lipid-enveloped drug permeation through an SLB formed on a mesoporous silica thin film (Paper III). The insights gained from investigating SLBs was also used for in depth characterization of BNPs using the surface-based flow-nanometry method, allowing for independent determination of size and fluorescence emission of individual BNPs tethered to a laterally fluid SLB formed on the floor of a microfluidic channel. This way we could demonstrate that the fluorescence emission from lipophilic dyes depends in a non-trivial way on nanoparticle size, and varies significantly between the different types of BNPs (Paper IV). The flow-nanometry concept was also used to elucidate the effect of vesicle size on their diffusivity on the SLB in the limit of few tethers (Paper V). The insights gained in this thesis work on lipid self-assembly at different surfaces and the possibility to use SLBs on silica for in-depth characterization of BNPs demonstrate this as a promising approach in the field of single nanoparticle analytics, which in future work will be possible to extend into a novel means to probe interactions between BNPs and cell-membrane mimics representing a near-native situation.
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| 5. |
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| 6. |
- Joyce, Paul, 1989, et al.
(författare)
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Enhancing the cellular uptake and antibacterial activity of rifampicin through encapsulation in mesoporous silica nanoparticles
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- An urgent demand exists for the development of novel delivery systems that efficiently transport antibacterial agents across cellular membranes for the eradication of intracellular pathogens. In this study, the clinically relevant poorly water-soluble antibiotic, rifampicin, was confined within mesoporous silica nanoparticles (MSN) to investigate their ability to serve as an efficacious nanocarrier system against small colony variants of Staphylococcus aureus (SCV S. aureus) hosted within Caco-2 cells. The surface chemistry and particle size of MSN were varied through modifications during synthesis, where 40 nm particles with high silanol group densities promoted enhanced cellular uptake. Extensive biophysical analysis was performed, using quartz crystal microbalance with dissipation (QCM-D) and total internal reflection fluorescence (TIRF) microscopy, to elucidate the mechanism of MSN adsorption onto semi-native supported lipid bilayers (snSLB) and, thus, uncover potential cellular uptake mechanisms of MSN into Caco-2 cells. Such studies revealed that MSN with reduced silanol group densities were prone to greater particle aggregation on snSLB, which was expected to restrict endocytosis. MSN adsorption and uptake into Caco-2 cells correlated well with antibacterial efficacy against SCV S. aureus, with 40 nm hydrophilic particles triggering a ~2.5-log greater reduction in colony forming units, compared to the pure rifampicin. Thus, this study provides evidence for the potential to design silica nanocarrier systems with controlled surface chemistries that can be used to re-sensitise intracellular bacteria to antibiotics by delivering them to the site of infection.
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| 7. |
- Joyce, Paul, 1989, et al.
(författare)
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TIRF Microscopy-Based Monitoring of Drug Permeation Across a Lipid Membrane Supported on Mesoporous Silica
- 2021
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Ingår i: Angewandte Chemie - International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 60:4, s. 2069-2073
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent demand for analytic approaches that enable precise and representative quantification of the transport of biologically active compounds across cellular membranes. In this study, we established a new means to monitor membrane permeation kinetics, using total internal reflection fluorescence microscopy confined to a ≈500 nm thick mesoporous silica substrate, positioned underneath a planar supported cell membrane mimic. This way, we demonstrate spatiotemporally resolved membrane permeation kinetics of a small-molecule model drug, felodipine, while simultaneously controlling the integrity of, and monitoring the drug binding to, the cell membrane mimic. By contrasting the permeation behaviour of pure felodipine with felodipine coupled to the permeability enhancer caprylate (C8), we provide evidence for C8-facilitated transport across lipid membranes, thus validating the potential for this approach to successfully quantify carrier system-induced changes to cellular membrane permeation.
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| 8. |
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| 9. |
- Lubart, Quentin, 1989, et al.
(författare)
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High throughput size-determination and multiplexed fluorescence analysis of single biological particles in a nanofluidic device
- 2019
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Ingår i: 23rd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2019. ; , s. 1420-1421
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Konferensbidrag (refereegranskat)abstract
- Biological nanoparticles, such as exosomes and viruses, are responsible for a multitude of important functions, but methods to characterize them on the single particle level are rare. We here present a nanofluidic platform for multi-parametric characterization of biological nanoparticles with high throughput. The device consists of feeding microchannels and an array of ~100 nanochannels where the nanoparticles can be characterized. We determine the size by analyzing the Brownian motion of the particles and quantify their content based on fluorescence imaging of up to three different colors. We successfully benchmark our method against existing techniques, such as Nanoparticle Tracking Analysis (NTA).
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| 10. |
- Mapar, Mokhtar, 1983, et al.
(författare)
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Spatiotemporal Kinetics of Supported Lipid Bilayer Formation on Glass via Vesicle Adsorption and Rupture
- 2018
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 9:17, s. 5143-5149
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Tidskriftsartikel (refereegranskat)abstract
- Supported lipid bilayers (SLBs) represent one of the most popular mimics of the cell membrane. Herein, we have used total internal reflection fluorescence microscopy for in-depth characterization of the vesicle-mediated SLB formation mechanism on a common silica-rich substrate, borosilicate glass. Fluorescently labeling a subset of vesicles allowed us to monitor the adsorption of individual labeled vesicles, resolve the onset of SLB formation from small seeds of SLB patches, and track their growth via SLB-edge-induced autocatalytic rupture of adsorbed vesicles. This made it possible to perform the first quantitative measurement of the SLB front velocity, which is shown to increase up to 1 order of magnitude with time. This effect can be classified as dramatic because in many other physical, chemical, or biological kinetic processes the front velocity is either constant or decreasing with time. The observation was successfully described with a theoretical model and Monte Carlo simulations implying rapid local diffusion of lipids upon vesicle rupture.
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