Veronika Kazikova
@sav.sk
Department of Biophysics, Institute of Experimental Physics
Slovak Academy of Sciences
Scopus Publications
Scopus Publications
Veronika KAŽIKOVÁ, Július VIDA, Petr RYŠÁNEK, Martin KORMUNDA, Pavla ČAPKOVÁ, and Tomáš HOMOLA
TANGER Ltd.
Polyvinylidene fluoride (PVDF) polymeric nanofibers deposited by roller electrospinning on polypropylene nonwoven fabric were treated with atmospheric pressure plasma to hydrophilize its surface. Diffuse coplanar surface barrier discharge (DCSBD) was employed to generate low-temperature atmospheric plasma in ambient air. Changes in wettability were determined by evaluating water contact angles before and after plasma treatment for various treatment times. The effect of aging of plasma-treated surfaces stored in laboratory conditions was studied in the course of storage time. The chemical composition of the surfaces was determined by X-ray photoelectron spectroscopy (XPS) which showed a decrease in carbon and an increase in oxygen atomic concentrations. Subsequently, significant differences in loading of iron oxide nanoparticles between treated and untreated PVDF samples were observed by scanning electron microscopy.
Jana Kubacková, Gergely T. Iványi, Veronika Kažiková, Alena Strejčková, Andrej Hovan, Gabriel Žoldák, Gaszton Vizsnyiczai, Lóránd Kelemen, Zoltán Tomori, and Gregor Bánó
AIP Publishing
Jana Kubackova, Veronika Kazikova, Gabriel Zoldak, Zoltan Tomori, and Gregor Bano
SPIE
Two-photon absorption polymerization (2PP) is a versatile lithographic method for building three-dimensional microdevices with sub-diffraction resolution and tunable elasticity. Using 2PP of organo-ceramic hybrid OrmoComp (trimethylolpropane triacrylate), we prepared microsized polymeric cantilevers consisting of the surface-anchored micropillar, long elastic neck and spherical head. A typical microcantilever has the length of 30 micrometers and thickness of 1-2 micrometers. To investigate the mechanical properties of our elastic microcantilever, we applied a laser optical trapping force on the head of the cantilever and bent the head from its equilibrium position. After switching off the laser trap, the head returns to the equilibrium position. The time-dependent restoring trajectory of the head was recorded by a fast video-tracking technique (500 fps) and subjected to the custom-made drift-correcting image analysis. We find that the microcantilever relaxation process is well-described by a single-exponential relaxation curve with a time constant of 16.5 ± 1.2 ms. Assuming a highly overdamped regime, theoretical calculations yielded an apparent Young´s modulus for our OrmoComp microstructure of 1 MPa, which is 3-orders of magnitude smaller than the reported value for the bulk material (~1 GPa). The possible reasons for such discrepancy are discussed.
Zoltan Tomori, Veronika Kazikova, Jana Kubackova, and Gregor Bano
SPIE
Elastic micro-cantilever of 30-micrometer size is repeatedly deflected/released by optical tweezers trap, recorded by a high-speed camera (500 frames/sec) and subsequently processed off-line. This paper evaluates the position detection methods of the cantilever head, which is distorted by a diffraction pattern. We developed and tested four methods in our VideoAnalyser software - radial extremes, Hough transform, local corner tracking, and voting normal lines. The time dependence of the head position contains the information about the properties of both: cantilever material and the surrounding environment. Averaging of aligned graphs corresponding to individual cycles significantly improves the signal-to-noise ratio.
Jaroslava Joniová, Veronika Kažiková, Emmanuel Gerelli, Gregor Bánó, and Georges Wagnières
SPIE-Intl Soc Optical Eng
Abstract. Models mimicking the endogenous production of protoporphyrin IX (PpIX), as well as its fluorescence, are of high interest for applied and fundamental studies in the fields of cancer detection by fluorescence imaging, photodynamic therapy (PDT), and photobiomodulation (PBM). Here, we present and describe optical properties of the yeast-based models able to produce PpIX endogenously after the administration of 5-aminolevulinic acid (ALA) and/or 2,2’-bipyridyl. As their optical properties have an important impact on the spatial distribution of the fluence rate in these liquid models, their absorption and reduced scattering coefficients were determined to be between 400 and 808 nm for two yeast solutions previously described by our group. These coefficients were derived from measurements of the total reflectance and light penetration depth using a dedicated Monte Carlo simulation. We observed that absorption and scattering coefficients were smaller than those of soft tissues at all wavelengths. This work will enable the production of a low-cost optical phantom loaded with appropriate amounts of light-absorbing and -scattering particles to mimic tumors containing PpIX, offering a useful tool to optimize the spectral and radiometric design of certain cancer photodetection setups.
M. Orendáč, E. Čižmár, V. Kažiková, A. Orendáčová, A. Řezníčková, Z. Kolská, and V. Švorčík
Elsevier BV
Abstract Electron-spin resonance of high-density polyethylene treated by Ar plasma at 300 K was performed in X-band at temperatures from 2.1 K to 290 K. The observed spectra suggest presence of allyl radicals, whereas the central peak may be attributed to polyenyl radicals or dangled bonds. Pronounced narrowing of the resonance line observed above glassy temperature of polyethylene may be ascribed to thermally activated motional effect with the activation energy E a / k B = 160 K. The absence of strong exchange interactions is suggested by negligible exchange narrowing found at 2.1 K. The suggestion is supported by the analysis of the temperature dependence of the intensity at low temperatures, which is explicable assuming the coexistence of non-interacting radicals and S = 1/2 dimers with a distribution of antiferromagnetic couplings varying from 2 K to nominally 25 K.