Search results

1

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

Atomic Force Microscopy and Quartz Crystal Microbalance Study of the Lectin-Carbohydrate Interaction Kinetics

100%

Lebed K., Kulik A., Forró L., Lekka M.

Acta Physica Polonica A

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2007

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vol. 111

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issue 2

273-286

EN

Two analytical methods, atomic force microscopy and quartz crystal microbalance, were applied to the study of the reaction kinetics occurring between concanavalin A and carboxypeptidase Y, presenting the specific lectin-carbohydrate recognition. The dissociation rate constants for concanavalin A-carboxypeptidase Y complex obtained using both atomic force microscopy and quartz crystal microbalance were of the same order of magnitude: k_{diss}=0.170± 0.060 s^{-1} and k_{diss}=0.095±0.002 s^{-1}, respectively. In addition, each method alone aided in determining other parameters characterizing the studied interaction. Quartz crystal microbalance permitted us to estimate the association rate (k_{ass}=(5.6 ±0.1)×10^4 M^{-1} s^{-1}) and the equilibrium (K_a=(0.59×0.01)×10^6 M^{-1}) constants for the binding process occurring between concanavalin A and mannose residues of carboxypeptidase Y under given experimental conditions. Atomic force microscopy in force spectroscopy mode enabled the determination of the energy barrier position of r=2.29±0.04 Å characterizing the dissociation of concanavalin A- carboxypeptidase Y molecular complex. The presented results show that both atomic force microscopy and quartz crystal microbalance can be used to determine quantitative parameters characterizing the specific molecular interaction. Both methods can be easily combined for complementary and/or alternative studies of a chosen molecular interaction. By preparing the samples in the same manner the direct comparison between the data obtained via atomic force microscopy and quartz crystal microbalance can be made.

3

Single-Bond Force Measured by Means of Scanning Force Microscopy

88%

Lekka M., Gryboś J., Lekki J., Stachura Z., Styczeń J.

Acta Physica Polonica A

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2002

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vol. 102

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issue 3

355-364

EN

The aim of this investigation was to determine the adhesion force as a function of calcium dichloride concentration in water. The studies were performed with two surfaces carrying opposite charge in water solution: mica - as a negatively charged surface and glass covered with poly-L-lysine - as a positively charged surface, the latter due to the presence of amino groups. The surfaces were immersed in a CaCl_2 solution in the range of concentration varied from 0 to 100 mM. The scanning force microscopy was applied to determine the adhesion force by measurements of the pull-off force. Additionally, the values of the single bond force were estimated basing on the Poisson distribution of the number of binding sites.

4

Scanning Force Microscopy Studies of Implanted Silicon Crystals

88%

Lekki J., Lekka M., Romano H., Cleff B., Stachura Z.

Acta Physica Polonica A

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1996

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vol. 89

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issue 3

315-322

EN

Scanning force microscope has been applied to investigate wear tracks produced during friction coefficient measurements of hard steel ball against ⟨111⟩ silicon crystals implanted with Ar ions. Such treatment causes the stable and significant decrease in friction, despite the total removal of implanted species from the wear track during friction. Scanning force microscope measurements of wear tracks topography supported the former hypothesis assuming the formation of post-implantation dense microcracks structure and subsequent propagation of this structure into the bulk. Such process assures small size of wear particles and a low friction coefficient value. Additionally the microfriction force measurement method was applied to determine the friction coefficient of Si_{3}N_{4} cantilever and a wear track in Si crystal.

5

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.

6

The Increase in Protein Contour Length Depends on Mechanical Unfolding Conditions

88%

Dąbrowska A., Lebed K., Lekka M., Kulik A., Forró L.

Acta Physica Polonica A

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2008

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vol. 113

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issue 2

753-762

EN

Many proteins in alive organisms have a domain structure providing them the possibility to reversible unfolding, which seems to play an essential role in those processes occurring in tissues which are controlled by mechanical cellular tension. In this work the atomic force microscopy was applied to investigate the mechanical properties of the single molecules of fibronectin, a protein participating in the important mechanical processes in extracellular matrix. The results showed that the conditions of mechanical stretching influence not only the force required to unfolding of a domain but also the increase in protein contour length induced by such unfolding event. Two mean values of the increase in length (called shortly the unfolding length) L_1 and L_2, were obtained and ascribed to unfolding of either the whole fibronectin domain of type III (L_2) or its fragment (L_1). Both unfolding lengths revealed similar dependence on the stretching conditions. This experimental observation of increase in unfolding length with increasing loading rate was successfully described with a combination of two theoretical models (Bell model and the worm-like-chain model), previously used separately in the analysis of protein unfolding. The general mechanical property of fibronectin domains was emphasized and proposed as a potential determinant of the cellular adhesion.

7

Local Adhesive Surface Properties Studied by Force Microscopy

88%

Lekka M., Lekki J., Marszałek M., Stachura Z., Cleff B.

Acta Physica Polonica A

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1998

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vol. 93

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issue 2

421-424

EN

Scanning force microscopy was used in the contact mode to determine the adhesion force between a mica surface and a silicon nitride tip. The measurements were performed in an aqueous solution of sodium and calcium chlorides. The adhesion force according to the Derjaguin-Landau-Verwey- Overbeek theory depends on the competition between two kinds of forces: van der Waals and electrostatic "double layer". Two different curves of adhesion force versus salt concentration were obtained from the experiment with monovalent and divalent ions. The tip-surface adhesion force was determined from a statistical analysis of data obtained from the force vs. distance retracting curves.

8

Study of Adhesion Interaction Using Atomic Force Microscopy

76%

Gryboś J., Pyka-Fościak G., Lebed K., Lekka M., Stachura Z., Styczeń J.

Acta Physica Polonica A

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2004

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vol. 105

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issue 5

501-510

EN

An atomic force microscope is a useful tool to study the interaction forces at molecular level. In particular the atomic force microscope can measure an unbinding force needed to separate the two single molecule complexes. Recent studies have shown that such unbinding force depends linearly on the logarithm of the applied loading rate, defined as a product of scanning velocity and the spring constant characterizing the investigated system (cantilever vs. surface). This dependence can be used to study the energy landscape shape of a molecular complex by the estimation of energy barrier locations and the related dissociation rates. In the present work the complex consisting of ethylene(di)aminetetraacetic acid and the bovine serum albumin was measured. The dependence between the unbinding force and the logarithm of the loading rate was linear. Using the Bell model describing the dissociation of the above molecules caused by the action of the external bond breaking force, two parameters were estimated: the dissociation rate and the position of the energy barrier needed to overcome during a transition from a bound to unbound state. The obtained results are similar to those obtained for a typical ligand-receptor interaction.

9

Structures in Multicomponent Polymer Films: Their Formation, Observation and Applications in Electronics and Biotechnology

64%

Budkowski A., Bernasik A., Moons E., Lekka M., Zemła J., Jaczewska J., Haberko J., Raczkowska J., Rysz J., Awsiuk K.

Acta Physica Polonica A

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2009

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vol. 115

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issue 2

435-440

EN

Several strategies to form multicomponent films of functional polymers, with micron, submicron and nanometer structures, intended for plastic electronics and biotechnology are presented. These approaches are based on film deposition from polymer solution onto a rotating substrate (spin-casting), a method implemented already on manufacturing lines. Film structures are determined with compositional (nanometer) depth profiling and (submicron) imaging modes of dynamic secondary ion mass spectrometry, near-field scanning optical microscopy (with submicron resolution) and scanning probe microscopy (revealing nanometer features). Self-organization of spin-cast polymer mixtures is discussed in detail, since it offers a one-step process to deposit and align simultaneously domains, rich in different polymers, forming various device elements: (i) Surface segregation drives self-stratification of nanometer lamellae for solar cells and anisotropic conductors. (ii) Cohesion energy density controls morphological transition from lamellar (optimal for encapsulated transistors) to lateral structures (suggested for light emitting diodes with variable color). (iii) Selective adhesion to substrate microtemplates, patterned chemically, orders lateral structures for plastic circuitries. (iv) Submicron imprints of water droplets (breath figures) decorate selectively micron-sized domains, and can be used in devices with hierarchic structure. In addition, selective protein adsorption to regular polymer micropatterns, formed with soft lithography after spin-casting, suggests applications in protein chip technology. An approach to reduce lateral blend film structures to submicron scale is also presented, based on (annealed) films of multicomponent nanoparticles.

10

Modification of Polymer Substrates with Extreme Ultraviolet - Potential Application in Cancer Cell Identification

64%

Ahad I., Pabijan J., Pogoda K., Hughes C., Bartnik A., Fiedorowicz H., Lekka M., Brabazon D.

Acta Physica Polonica A

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2018

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vol. 133

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issue 2

283-285

EN

During the last two decades, the development of laboratory scale extreme ultraviolet sources has been intensified due to growing interest in use of extreme ultraviolet photons for various applications in science and technology. In this study, we present a potential application of extreme ultraviolet sources for surface modification of polymers to be used as substrates for cancer cell identification. The surface modification of polytetrafluoroethylene (PTFE) polymer samples was performed by a lab scale compact laser-plasma extreme ultraviolet source based on a double-stream gas-puff target. The gas target was irradiated with a 3 ns/0.8 J Nd:YAG laser pulse at 10 Hz. Reference HCV29 non-malignant transitional epithelium and T24 bladder cancer cells adhesion and proliferation studies on pure and extreme ultraviolet sources modified PTFE surfaces were performed. The extreme ultraviolet modified surfaces demonstrated regular increase in cancer cell proliferation comparing to pristine sample. Initial results indicate that extreme ultraviolet treated substrates can facilitate the identification of cancer cells.

11

Contact Microscopy using a Compact Laser Produced Plasma Soft X-Ray Source

52%

Ayele M., Czwartos J., Adjei D., Wachulak P., Ahad I., Bartnik A., Wegrzynski Ł., Szczurek M., Jarocki R., Fiedorowicz H., Lekka M., Pogoda K., Gostek J.

Acta Physica Polonica A

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2016

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vol. 129

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issue 2

237-240

EN

Soft X-ray contact microscopy potentially allows imaging of wet living biological specimens at a spatial resolution higher than optical microscopy and without many of the constraints of scanning electron microscopy. In this paper, we present the development of a laboratory scale contact microscope that uses a laser produced plasma soft X-ray source. The source is based on a double-stream gas-puff target approach and it operates in the "water window" spectral range which enables to capture images of biological samples with a natural contrast. In the preliminary experiments the contact microscope system has been used for imaging of fixed and dried non-malignant HCV29 human bladder cell lines cultured on polymethyl methacrylate photoresists. The samples were exposed with 150 pulses of soft X-rays as an initial test to demonstrate the possibility of image formation. The soft X-ray contact images registered in the photoresists exhibit high resolution in the atomic force microscopy topography which indicates the potential application of soft X-ray contact microscopy in life science to examine small features as small as few tens of nm. The technique could also be used for living cell imaging with further optimization of the microscope system and development of a special specimen holder. The details of the soft X-ray contact microscopy technique and the experimental results are presented and discussed.

Refine search results

Energy Dissipation in the AFM Elasticity Measurements

Atomic Force Microscopy and Quartz Crystal Microbalance Study of the Lectin-Carbohydrate Interaction Kinetics

Single-Bond Force Measured by Means of Scanning Force Microscopy

Scanning Force Microscopy Studies of Implanted Silicon Crystals

Implementation of NSOM to Biological Samples

The Increase in Protein Contour Length Depends on Mechanical Unfolding Conditions

Local Adhesive Surface Properties Studied by Force Microscopy

Study of Adhesion Interaction Using Atomic Force Microscopy

Structures in Multicomponent Polymer Films: Their Formation, Observation and Applications in Electronics and Biotechnology

Modification of Polymer Substrates with Extreme Ultraviolet - Potential Application in Cancer Cell Identification

Contact Microscopy using a Compact Laser Produced Plasma Soft X-Ray Source