| 1. |
- Bauer, Brigitte, 1978, et al.
(author)
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Metal nanoparticles amplify photodynamic effect on skin cells in vitro
- 2011
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In: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. Optical Interactions with Tissue and Cells XXII; San Francisco, CA; 24-26 January 2011. - : SPIE. - 1605-7422. - 9780819484345 ; 7897
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Conference paper (other academic/artistic)abstract
- We report on an investigation aimed to increase the efficiency of photodynamic therapy (PDT) through the influence of localized surface plasmon resonances (LSPR's) in metal nanoparticles. PDT is based on photosensitizers that generate singlet oxygen at the tumour site upon exposure to visible light. Although PDT is a well-established treatment for skin cancer, a major drawback is the low quantum yield for singlet-oxygen production. This motivates the development of novel methods that enhance singlet oxygen generation during treatment. In this context, we study the photodynamic effect on cultured human skin cells in the presence or absence of gold nanoparticles with well established LSPR and field-enhancement properties. The cultured skin cells were exposed to protoporphyrin IX and gold nanoparticles and subsequently illuminated with red light. We investigated the differences in cell viability by tuning different parameters, such as incubation time and light dose. In order to find optimal parameters for specific targeting of tumour cells, we compared normal human epidermal keratinocytes with a human squamous skin cancer cell line. The study indicates significantly enhanced cell death in the presence of nanoparticles and important differences in treatment efficiency between normal and tumour cells. These results are thus promising and clearly motivate further development of nanoparticle enhanced clinical PDT treatment.
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| 2. |
- Bauer, Brigitte, 1978, et al.
(author)
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Modification and expulsion of keratins by human epidermal keratinocytes upon hapten exposure in vitro.
- 2011
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In: Chemical research in toxicology. - : American Chemical Society (ACS). - 1520-5010 .- 0893-228X. ; 24:5, s. 737-43
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Journal article (peer-reviewed)abstract
- Allergic contact dermatitis is the most prevalent form of human immunotoxicity. It is caused by reactive low molecular weight chemicals, that is, haptens, coming in contact with the skin where hapten-peptide complexes are formed, activating the immune system. By using sensitizing fluorescent thiol-reactive haptens, that is, bromobimanes, we show how keratinocytes respond to hapten exposure in vitro and reveal, for the first time in a living system, an exact site of haptenation. Rapid internalization and reaction of haptens with keratin filaments were visualized. Subsequently, keratinocytes respond in vitro to hapten exposure by release of membrane blebs, which contain haptenated keratins 5 and 14. Particularly, cysteine 54 of K5 was found to be a specific target. A mechanism is proposed where neoepitopes, otherwise hidden from the immune system, are released after hapten exposure via keratinocyte blebbing. The observed expulsion of modified keratins by keratinocytes in vitro might play a role during hapten sensitization in vivo and should be subject to further investigations.
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| 3. |
- Kirejev, Vladimir, 1984, et al.
(author)
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Novel nanocarriers for topical drug delivery: investigating delivery efficiency and distribution in skin using two-photon microscopy
- 2011
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In: Proc. SPIE, Multiphoton Microscopy in the Biomedical Sciences XI, editors: Ammasi Periasamy, Karsten König, Peter T. C. So, 23 January 2011. - : SPIE. ; 7903:1
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Conference paper (peer-reviewed)abstract
- The complex structure of skin represents an effective barrier against external environmental factors, as for example, different chemical and biochemical compounds, yeast, bacterial and viral infections. However, this impermeability prevents efficient transdermal drug delivery which limits the number of drugs that are able to penetrate the skin efficiently. Current trends in drug application through skin focus on the design and use of nanocarriers for transport of active compounds. The transport systems applied so far have several drawbacks, as they often have low payload, high toxicity, a limited variability of inclusion molecules, or long degradation times. The aim of these current studies is to investigate novel topical drug delivery systems, e.g. nanocarriers based on cyclic oligosaccharides - cyclodextrins (CD) or iron (III)-based metal-organic frameworks (MOF). Earlier studies on cell cultures imply that these drug nanocarriers show promising characteristics compared to other drug delivery systems. In our studies, we use two-photon microscopy to investigate the ability of the nanocarriers to deliver compounds through ex-vivo skin samples. Using near infrared light for excitation in the so called optical window of skin allows deep-tissue visualization of drug distribution and localization. In addition, it is possible to employ two-photon based fluorescence correlation spectroscopy for quantitative analysis of drug distribution and concentrations in different cell layers.
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| 4. |
- Rago, Gianluca, et al.
(author)
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Uptake of gold nanoparticles in healthy and tumor cells visualized by nonlinear optical microscopy
- 2011
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In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 115:17, s. 5008-16
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Journal article (peer-reviewed)abstract
- Understanding the mechanism underlying the interactions between inorganic nanostructures and biological systems is crucial for several rapidly growing fields that rely on nano-bio interactions. In particular, the further development of cell-targeted drug delivery using metallic nanoparticles (NP) requires new tools for understanding the mechanisms triggered by the contact of NPs with membranes in different cells at the subcellular level. Here we present a novel concept of multimodal microscopy, enabling three-dimensional imaging of the distribution of gold NPs in living, unlabeled cells. Our approach combines multiphoton induced luminescence (MIL) with coherent anti-Stokes Raman scattering (CARS) microscopy. Comparison with transmission electron microscopy (TEM) reveals in vivo sensitivity down to the single nanostructure. By monitoring the incorporation of NPs in human healthy epidermal keratinocytes and squamous carcinoma cells (SCC), we address the feasibility of noninvasive delivery of NPs for therapeutic purposes. While neutralizing PEG coating was confirmed to prevent NP integration in SCCs, an unexpectedly efficient integration of NPs into keratinocytes was observed. These results, independently validated using TEM, demonstrate the need for advanced surface modification protocols to obtain tumor selectivity for NP delivery. The CARS/MIL microscopy platform presented here is thus a promising tool for noninvasive study of the interaction between NPs and cell.
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| 5. |
- Simonsson, Carl, 1976, et al.
(author)
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Caged fluorescent haptens reveal the generation of cryptic epitopes in allergic contact dermatitis.
- 2011
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In: The Journal of investigative dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 131:7, s. 1486-93
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Journal article (peer-reviewed)abstract
- Allergic contact dermatitis (ACD) is the most prevalent form of human immunotoxicity. It is caused by skin exposure to haptens, i.e., protein-reactive, low-molecular-weight chemical compounds, which form hapten-protein complexes (HPCs) in the skin, triggering the immune system. These immunogenic HPCs are elusive. In this study a series of thiol-reactive caged fluorescent haptens, i.e., bromobimanes, were deployed in combination with two-photon fluorescence microscopy, immunohistochemistry, and proteomics to identify possible hapten targets in proteins in human skin. Key targets found were the basal keratinocytes and the keratins K5 and K14. Particularly, cysteine 54 of K5 was found to be haptenated by the bromobimanes. In addition, elevated levels of anti-keratin antibodies were found in the sera of mice exposed to bromobimanes in vivo. The results indicate a general mechanism in which thiol-reactive haptens generate cryptic epitopes normally concealed from the immune system. In addition, keratinocytes and keratin seem to have an important role in the mechanism behind ACD, which is a subject for further investigations.
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