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Energy Dissipation in the AFM Elasticity Measurements

100%
Klymenko O., Wiltowska-Zuber J., Lekka M., Kwiatek W.
Acta Physica Polonica A
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2009
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vol. 115
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issue 2
548-551
EN
Nowadays, it is well established that changes of cell stiffness observed by atomic force microscopy are linked with the cell cytoskeleton. Its structural and functional alterations are underlying major diseases such as cancer, inflammation or neurodegenerative disorders. So far, the use of atomic force microscopy is mostly focused on the determination of the Young modulus using the modified Hertz model. It can quantitatively describe the elastic properties of living cells, however, its value is burdened by the fact that cells are neither isotropic nor homogeneous material. Often, during the atomic force microscopy measurements, the hysteresis between the loading and unloading curves are observed which indicates the dissipation of an energy. In our studies, the index of plasticity was introduced to enumerate such effect during a single loading-unloading cycle. As the results show, such approach delivers an additional parameter describing the mechanical state of cell cytoskeleton. The analysis was performed on test samples where the mechanical properties of the melanoma cells were changed by glutaraldehyde and cytochalasin D treatments. The non-treated cells were compared with fibroblasts.
2
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Implementation of NSOM to Biological Samples

88%
Prauzner-Bechcicki S., Wiltowska-Zuber J., Budkowski A., Lekka M., Rysz J.
Acta Physica Polonica A
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2012
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vol. 121
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issue 2
533-538
EN
Near-field scanning optical microscopy is a technique providing images of structures with spatial resolution better than λ/2, which is undetectable in far-field where the Abbe law of limiting resolution is critical. In parallel to the optical imaging, topography maps are also acquired. Near-field scanning optical microscopy measurements can be performed both in air and liquid environments. The later makes the technique very useful for biomaterials analysis offering information that could not be obtained with other methods. Our work presents the results of recent studies on application of near-field scanning optical microscopy to imaging of cells in air as well as in physiological buffers. Differences in cell's topography and morphology have been noticed between two cell lines from human bladder non-malignant (HCV29) and malignant (T24) cancers. Presented results are part of the research that characterizes physiological changes of cells depending on stage of cancer.
3
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Applications of Comet Assay for the Evaluation of Genotoxicity and DNA Repair Efficiency in Nanomaterials Research

76%
Panek A., Błażewicz M., Frączek-Szczypta A., Adamczyk J., Wiltowska-Zuber J., Paluszkiewicz C.
Acta Physica Polonica A
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2018
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vol. 133
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issue 2
280-282
EN
The single cell gel electrophoresis method, known as comet assay, is a rapid and sensitive technique for testing novel chemicals and nanoparticles for genotoxicity, monitoring environmental contamination with genotoxins and human biomonitoring. In our studies we check the applicability of this method for the evaluation of biocompatibility of modified (MWNF) and non-modified multi-walled carbon nanotubes (MWNT) as well as potential genotoxicity of mercury(II) nitrate. The obtained results enabled us to conclude that the presence of Hg(NO₃)₂ (p<0.001) and MWNT (p<0.04) cause a significantly higher level of DNA damage in comparison to functionalised nanomaterials MWNF. It was implied that for the three investigated agents only mercury significantly enhanced genotoxic effect of X-ray exposure (p<0.001) and inhibition of radio-induced DNA damage repair. On the contrary, the presence of MWNF have no influence on cellular repair efficiencies, while incubation with MWNT causes apoptosis and consequently results in lack of attached cells. In conclusion, our results confirmed the genotoxicity of mercury and non-modified carbon nanotubes as well as the biocompatibility of modified nanotubes. Additionally, we proved the usefulness of comet method for the evaluation of genotoxicity and DNA repair under the influence of different compounds and nanomaterials.
4
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Comparison of Methods in Studies of Cell Death Mechanisms

76%
Borkowska A., Nowakowski M., Miszczyk J., Lipiec E., Wiltowska-Zuber J., Rawojć K., Kwiatek W.
Acta Physica Polonica A
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2018
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vol. 133
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issue 2
263-266
EN
While studying the influence of ionizing radiation or certain chemical agents on cells, it is crucial to not only determine cytotoxicity, but also to follow cell death mechanisms. There are different methods to screen processes of cell death and still very important question remains unanswered about differences in results that could be caused by various experimental steps in procedures. Based on literature review two protocols of cell death determination were compared. First protocol regarded collecting cells floating in medium before trypsinization and following centrifugation of them. In the second protocol floating cells were discarded and attached ones were stained and fixed. In all experiments three different untreated cell lines (A172, DU145 as cancer cell lines and in comparison, fibroblasts (FB CCL 110), as a non- cancerous cell line) were used to test applied protocols. Cells were cultured and death processes were examined at different time points up to 120 h. Compared protocols showed statistically significant differences, especially in terms of necrosis, which was higher when included floating cells from culture medium and then centrifuging them. Therefore, presented results show importance of choosing a valid experimental procedure in case of evaluating cells viability and types of cell death pathways quantitatively.
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