| 1. |
- Eskilson, Olof, 1992-, et al.
(författare)
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Self-Assembly of Mechanoplasmonic Bacterial Cellulose-Metal Nanoparticle Composites
- 2020
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlagsgesellschaft. - 1616-301X .- 1616-3028. ; 30:40
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Tidskriftsartikel (refereegranskat)abstract
- Nanocomposites of metal nanoparticles (NPs) and bacterial nanocellulose (BC) enable fabrication of soft and biocompatible materials for optical, catalytic, electronic, and biomedical applications. Current BC-NP nanocomposites are typically prepared by in situ synthesis of the NPs or electrostatic adsorption of surface functionalized NPs, which limits possibilities to control and tune NP size, shape, concentration, and surface chemistry and influences the properties and performance of the materials. Here a self-assembly strategy is described for fabrication of complex and well-defined BC-NP composites using colloidal gold and silver NPs of different sizes, shapes, and concentrations. The self-assembly process results in nanocomposites with distinct biophysical and optical properties. In addition to antibacterial materials and materials with excellent senor performance, materials with unique mechanoplasmonic properties are developed. The homogenous incorporation of plasmonic gold NPs in the BC enables extensive modulation of the optical properties by mechanical stimuli. Compression gives rise to near-field coupling between adsorbed NPs, resulting in tunable spectral variations and enhanced broadband absorption that amplify both nonlinear optical and thermoplasmonic effects and enables novel biosensing strategies.
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| 2. |
- Stenqvist, Björn, et al.
(författare)
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Membrane permeability based on mesh analysis
- 2023
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 633, s. 526-535
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Tidskriftsartikel (refereegranskat)abstract
- The main function of a membrane is to control the exchange of matter between the surrounding regions. As such, accurate modeling of membranes is important to properly describe their properties. In many cases in both biological systems and technical applications, the membranes are composite structures where transport properties may vary between the different sub-regions of the membrane. In this work we develop a method based on Mesh analysis that is asymptotically exact and can describe diffusion in composite membrane structures. We do this by first reformulating a generalized Fick's law to include the effects from activity coefficient, diffusion coefficient, and solubility using a single condensed param-eter. We then use the derived theory and Mesh analysis to, in essence, retrieve a finite element method approach. The calculated examples are based on a membrane structure that reassembles that of the brick and mortar structure of stratum corneum, the upper layer of our skin. Resulting concentration profiles from this procedure are then compared to experimental results for the distribution of different probes within intact stratum corneum, showing good agreement. Based on the derived approach we further investigate the impact from a gradient in the fluidity of the stratum corneum mortar lipids across the membrane, and find that it is substantial. We also show that anisotropic organisation of the lipid mortar can have large impact on the effective permeability compared to isotropic mortar lipids. Finally, we examine the effects of corneocyte swelling, and their lateral arrangement in the membrane on the overall membrane permeability.
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| 3. |
- Topel, S. D., et al.
(författare)
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Cellulose acetate encapsulated upconversion nanoparticles – A novel theranostic platform
- 2021
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Ingår i: Materials Today Communications. - : Elsevier BV. - 2352-4928. ; 26
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Tidskriftsartikel (refereegranskat)abstract
- Luminescent upconversion nanoparticles (UCNPs) are of great interest in a wide range of nanotechnological applications, particularly in the biomedical area like imaging and therapy but their biocompatibility and stability pose major challenges hampering progression towards further pharmaceutical applications. Herein, we present a biocompatible theranostic platform enabling simultaneous diagnosis and drug delivery consisting of UCNPs encapsulated with cellulose acetate (CA), a biocompatible polymer. Luminescence properties of UCNPs in the developed theranostic platform remain stable even after encapsulation. The size of the CA capsules, ranging from micro- to nano-sized particles, can easily be tuned by adjusting the stirring rate during encapsulation. Doxorubicin, a well-known chemotherapeutic drug, onto the CA nanocapsules containing UCNPs (UCNP-CA nanocapsules) was loaded with up to ∼63 % efficiency and acid-induced release (∼47 %) obtained at pH 3.6 and 5.5. It was found that encapsulation decreased toxicity of UCNPs as confirmed in a cellular assay (L-929 and MCF-7 cell lines). Taken together, the developed UCNP-CA nanocapsules serve as a highly interesting novel theranostic platform, combining the biocompatible optical properties of UCNP, with reduced cell toxicity and drug encapsulating properties of CA. The proposed system could be subject for further refinement and exploration. © 2020 Elsevier Ltd
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| 4. |
- Gunnarsson, Maria, et al.
(författare)
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Molecular Mobility in Keratin-Rich Materials Monitored by Nuclear Magnetic Resonance : A Tool for the Evaluation of Structure-Giving Properties
- 2023
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Ingår i: Biomacromolecules. - 1525-7797. ; 24:6, s. 2661-2673
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Tidskriftsartikel (refereegranskat)abstract
- Keratins are structural proteins that are abundant in human skin, nails, and hair, where they provide mechanical strength. In the present study, we investigate the molecular mobilities and structures of three keratin-rich materials with clearly different mechanical properties: nails, stratum corneum (upper layer of epidermis), and keratinocytes (from lower layer of epidermis). We use solid-state NMR on natural-abundance 13C to characterize small changes in molecular dynamics in these biological materials with close to atomistic resolution. One strong advantage of this method is that it detects small fractions of mobile components in a molecularly complex material while it simultaneously gives information on the rigid components in the very same sample. The molecular mobility can be linked to mechanical material properties in different conditions, including hydration or exposure to osmolytes or organic solvents. Importantly, the study revealed that the response to both hydration and addition of urea is clearly different for the nail keratin compared to the stratum corneum keratin. The comparative examination of these materials may provide a better understanding of skin diseases originating from keratin malfunction and contributes to the design and development of new materials.
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| 5. |
- James, Jeemol, et al.
(författare)
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Fluorescence Correlation Spectroscopy Combined with Multiphoton Laser Scanning Microscopy-A Practical Guideline
- 2021
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Multiphoton laser scanning microscopy (MPM) has opened up an optical window into biological tissues; however, imaging is primarily qualitative. Cell morphology and tissue architectures can be clearly visualized but quantitative analysis of actual concentration and fluorophore distribution is indecisive. Fluorescence correlation spectroscopy (FCS) is a highly sensitive photophysical methodology employed to study molecular parameters such as diffusion characteristics on the single molecule level. In combination with laser scanning microscopy, and MPM in particular, FCS has been referred to as a standard and highly useful tool in biomedical research to study diffusion and molecular interaction with subcellular precision. Despite several proof-of-concept reports on the topic, the implementation of MPM-FCS is far from straightforward. This practical guideline aims to clarify the conceptual principles and define experimental operating conditions when implementing MPM-FCS. Validation experiments in Rhodamine solutions were performed on an experimental MPM-FCS platform investigating the effects of objective lens, fluorophore concentration and laser power. An approach based on analysis of time-correlated single photon counting data is presented. It is shown that the requirement of high numerical aperture (NA) objective lenses is a primary limitation that restricts field of view, working distance and concentration range. Within these restrictions the data follows the predicted theory of Poisson distribution. The observed dependence on laser power is understood in the context of perturbation on the effective focal volume. In addition, a novel interpretation of the effect on measured diffusion time is presented. Overall, the challenges and limitations observed in this study reduce the versatility of MPM-FCS targeting biomedical research in complex and deep tissue-being the general strength of MPM in general. However, based on the systematic investigations and fundamental insights this report can serve as a practical guide and inspire future research, potentially overcoming the technical limitations and ultimately allowing MPM-FCS to become a highly useful tool in biomedical research.
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| 6. |
- James, Jeemol, et al.
(författare)
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Report on fluorescence lifetime imaging using multiphoton laser scanning microscopy targeting sentinel lymph node diagnostics.
- 2020
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Ingår i: Journal of biomedical optics. - 1560-2281. ; 25:7, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Sentinel lymph node (SLN) biopsy is an important method for metastasis staging in, e.g., patients with malignant melanoma. Tools enabling prompt histopathological analysis are expected to facilitate diagnostics; optical technologies are explored for this purpose.The objective of this exploratory study was to investigate the potential of adopting multiphoton laser scanning microscopy (MPM) together with fluorescence lifetime analysis (FLIM) for the examination of lymph node (LN) tissue ex vivo.Five LN tissue samples (three metastasis positive and two negative) were acquired from a biobank comprising tissues from melanoma patients. Tissues were deparaffinized and subjected to MPM-FLIM using an experimental MPM set-up equipped with a time correlated single photon counting module enabling FLIM.The data confirm that morphological features similar to conventional histology were observed. In addition, FLIM analysis revealed elevated morphological contrast, particularly for discriminating between metastatic cells, lymphocytes, and erythrocytes.Taken together, the results from this investigation show promise for adopting MPM-FLIM in the context of SLN diagnostics and encourage further translational studies on fresh tissue samples.
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| 7. |
- Kantere, Despoina, et al.
(författare)
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Label-free laser scanning microscopy targeting sentinel lymph node diagnostics: A feasibility study ex vivo
- 2020
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Ingår i: Translational Biophotonics. - : Wiley. - 2627-1850. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- This proof-of-concept, observational study investigates the potential for label-free, laser scanning microscopy to identify melanoma metastatic features in lymph node tissues ex vivo - exploring the translational potential targeting sentinel lymph node diagnostics. Ten lymph node samples, of which seven are positive for melanoma metastases and three negative, were obtained from a tissue biobank. Imaging data acquired using multiphoton microscopy ex vivo were compared with histopathological findings. Morphologic features characteristic for histopathologic diagnosis of melanoma metastasis were confirmed in the positive samples. Four of the samples were complementary studied with reflectance mode confocal microscopy; however, visualization was found restricted to fibrous structures in this case. To conclude, the results imply that multiphoton microscopy based on autofluorescence is a promising label-free technique for visualization of cellular features in lymph node tissues.
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| 8. |
- Malak, Monika, 1993, et al.
(författare)
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Contribution of autofluorescence from intracellular proteins in multiphoton fluorescence lifetime imaging.
- 2022
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Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Multiphoton fluorescence lifetime imaging microscopy (MPM-FLIM) is extensively proposed as a non-invasive optical method to study tissue metabolism. The approach is based on recording changes in the fluorescence lifetime attributed to metabolic co-enzymes, of which nicotinamide adenine dinucleotide (NADH) is of major importance. However, intrinsic tissue fluorescence is complex. Particularly when utilizing two-photon excitation, as conventionally employed in MPM. This increases the possibility for spectral crosstalk and incorrect assignment of the origin of the FLIM signal. Here we demonstrate that in keratinocytes, proteins such as keratin may interfere with the signal usually assigned to NADH in MPM-FLIM by contributing to the lifetime component at 1.5ns. This is supported by a change in fluorescence lifetime distribution in KRT5- and KRT14-silenced cells. Altogether, our results suggest that the MPM-FLIM data originating from cellular autofluorescence is far more complex than previously suggested and that the contribution from other tissue constituents should not be neglected-changing the paradigm for data interpretation in this context.
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| 9. |
- Malak, Monika, 1993, et al.
(författare)
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Monitoring calcium-induced epidermal differentiation in vitro using multiphoton microscopy
- 2020
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Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 25:7, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- SIGNIFICANCE: Research in tissue engineering and in vitro organ formation has recently intensified. To assess tissue morphology, the method of choice today is restricted primarily to histology. Thus novel tools are required to enable noninvasive, and preferably label-free, three-dimensional imaging that is more compatible with futuristic organ-on-a-chip models. AIM: We investigate the potential for using multiphoton microscopy (MPM) as a label-free in vitro approach to monitor calcium-induced epidermal differentiation. APPROACH: In vitro epidermis was cultured at the air-liquid interface in varying calcium concentrations. Morphology and tissue architecture were investigated using MPM based on visualizing cellular autofluorescence. RESULTS: Distinct morphologies corresponding to epidermal differentiation were observed. In addition, Ca2+-induced effects could be distinguished based on the architectural differences in stratification in the tissue cultures. CONCLUSIONS: Our study shows that MPM based on cellular autofluorescence enables visualization of Ca2+-induced differentiation in epidermal skin models in vitro. The technique has potential to be further adapted as a noninvasive, label-free, and real-time tool to monitor tissue regeneration and organ formation in vitro.
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| 10. |
- Thomsen, Hanna, 1989, et al.
(författare)
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Increased antibiotic efficacy and noninvasive monitoring of Staphylococcus epidermidis biofilms using per-cysteamine-substituted γ-cyclodextrin - A delivery effect validated by fluorescence microscopy.
- 2020
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Ingår i: International journal of pharmaceutics. - : Elsevier BV. - 1873-3476 .- 0378-5173. ; 587
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Tidskriftsartikel (refereegranskat)abstract
- Limited and poor delivery of antibiotics is cited as one reason for the difficulty in treating antibiotic-resistant biofilms associated with chronic infections. We investigate the effectiveness of a positively charged, single isomer cyclodextrin derivative, octakis[6-(2-aminoethylthio)-6-deoxy]-γ-CD (γCys) to improve the delivery of antibiotics to biofilms. Using multiphoton laser scanning microscopy complemented with super-resolution fluorescence microscopy, we showed that γCys tagged with fluorescein (FITC) is uniformly distributed throughout live S. epidermidis biofilm cultures in vitro and results suggest it is localized extracellularly in the biofilm matrix. NMR spectroscopic data in aqueous solution confirm that γCys forms inclusion complexes with both the antibiotics oxacillin and rifampicin. Efficacy of γCys/antibiotic (oxacillin and rifampicin) was measured in the biofilms. While treatment with γCys/oxacillin had little improvement over oxacillin alone, γCys/rifampicin reduced the biofilm viability to background levels demonstrating a remarkable improvement over rifampicin alone. The strong synergistic effect for γCys/rifampicin is at this stage not clearly understood, but plausible explanations are related to increased solubility of rifampicin upon complexation and/or synergistic interference with components of the biofilm. The results demonstrate that designed cyclodextrin nanocarriers, like γCys, efficiently deliver suitable antibiotics to biofilms and that fluorescence microscopy offers a novel approach for mechanistic investigations.
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