1. The synthesis, surface analysis, and cellular response of titania and titanium oxynitride nanotube arrays prepared on TiAl6V4 for potential biomedical applicationsKatja Andrina Kravanja, Luka Suhadolnik, Marjan Bele, Uroš Maver, Jan Rožanc, Željko Knez, Maša Knez Marevci, Matjaž Finšgar, 2023, original scientific article Abstract: Titania nanotubes are gaining prominence in the biomedical field as implant materials due to their mechanical durability, nano-rough properties, and positive influence on cellular response. This work aimed to synthesize titania and titanium oxynitride (TieOeN) nano- tubular arrays on TiAl6V4 substrates using an anodic oxidation process followed by annealing in air or by additional nitridation in NH3 atmosphere. Different nanotubular layers of unique morphology and structure were fabricated and investigated using advanced surface analysis and biocompatibility tests. In-depth surface analysis was per- formed by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), 3D profilometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Cell testing using adipose- derived mesenchymal stem cells and human fetal osteoblasts demonstrated good cell viability, high proliferative capacity, and a favorable overall effect on cell morphology for the TieOeN nanotubes.
Keywords: surface analysis, XPS, AFM, tandem ToF-SIMS, titania nanotubes, Ti-O-N nanotubes, anodization
Published in DKUM: 07.05.2024; Views: 186; Downloads: 20
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2. In Vitro Bioelectrochemical Properties of Second-Generation Oxide Nanotubes on Ti–13Zr–13Nb Biomedical AlloyAgnieszka Stróż, Thomas Luxbacher, Karolina Dudek, Bartosz Chmiela, Patrycja Osak, Bożena Łosiewicz, 2023, original scientific article Keywords: anodizing, corrosion resistance, oxide nanotubes, Ti–13Zr–13Nb alloy, zeta potential
Published in DKUM: 04.04.2024; Views: 193; Downloads: 7
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3. Nanomaterials and their recent applications in impedimetric biosensingZala Štukovnik, Regina Fuchs-Godec, Urban Bren, 2023, review article Abstract: Impedimetric biosensors measure changes in the electrical impedance due to a biochemical process, typically the binding of a biomolecule to a bioreceptor on the sensor surface. Nanomaterials can be employed to modify the biosensor's surface to increase the surface area available for biorecognition events, thereby improving the sensitivity and detection limits of the biosensor. Various nanomaterials, such as carbon nanotubes, carbon nanofibers, quantum dots, metal nanoparticles, and graphene oxide nanoparticles, have been investigated for impedimetric biosensors. These nanomaterials have yielded promising results in improving sensitivity, selectivity, and overall biosensor performance. Hence, they offer a wide range of possibilities for developing advanced biosensing platforms that can be employed in various fields, including healthcare, environmental monitoring, and food safety. This review focuses on the recent developments in nanoparticle-functionalized electrochemical-impedimetric biosensors.
Keywords: impedimetric biosensor, electrochemical impedance spectroscopy, nanomaterials, metal nanoparticles, carbon nanofibers, carbon nanotubes, graphene oxide, quantum dots
Published in DKUM: 12.02.2024; Views: 6175; Downloads: 24
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4. On the role of anisotropy of membrane constituents on the elastic properties of highly curved lipid membranesŠarka Perutkova, 2017, doctoral dissertation Abstract: The primary objective of the thesis covers in the theoretical study the role of
anisotropic membrane components in the elasticity of highly curved biological
membranes. To show the importance of anisotropy, we focused on one
type of non-lamellar membrane self-assembly - the inverted hexagonal phase
and the membrane tubular protrusions with attached proteins. These two
structures represent excellent examples of highly curved structures in which
the anisotropy of molecules or small domains plays an important role. In
the first part of the thesis, we developed a theoretical model describing the
stability of the inverted hexagonal phase, which considers lipid anisotropy
and deviations from the circularity of the pivotal plane cross-section. We applied
a wedge-like model of phospholipid molecules, in which the phospholipid
molecule is described as a wedge, with the angle of the wedge increasing with
temperature. However, we also took into account the average orientation of
lipids by including the deviatoric bending energy contribution derived from
statistical physics. Theoretical predictions of our model showed that a crosssection
of the inverted hexagonal phase is an intermediate between a circle
and a hexagon, and that it has lower energy than the circular cross-section.
The results were in agreement with observations gathered by the small angle
X-ray scattering. By comparing our results with the experiments, we
predicted some values of the mean intrinsic curvature and the phospholipid
chain stiffness. In the second part of the thesis, we developed a theoretical
model, which describes the stabilisation of membrane nanotubes containing
attached anisotropic flexible rod-like proteins. We derived the free energy
of a vesicle with nanotube taking into account the rotational averaging of
the anisotropic attached proteins. We also added the entropy contribution
due to the non-homogeneous lateral distribution of proteins. Our theoretical
results showed that rod-like attached proteins and membrane domains
can stabilise the membrane tubular protrusions if we consider the protein/
domain anisotropy. Our results were also in agreement with experimental results
in which isotropic membrane constituents were found on the tips of the
nanotube or on the mother vesicle; however, the anisotropic membrane constituents
were detected along the nanotubes. Our results showed that rod-like
attached proteins and membrane domains can stabilise the membrane tubular
protrusions if we consider the protein/domain anisotropy. The anisotropy of membrane constituents can lower the membrane free energy in regions of high
curvature. The main aim of the thesis was to show that the anisotropy of
membrane constituents can lower the membrane free energy in regions of high
curvature and that the rotational averaging of anisotropic membrane components
should be considered in the evaluation of the membrane free energy at
highly curved membrane structures.
Keywords: Biomembranes, Lipid anisotropy, Inverted hexagonal phase, Rotational averaging, Rod-like proteins, Membrane nanotubes, Membrane
protein sorting
Published in DKUM: 25.05.2017; Views: 2372; Downloads: 109
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5. Qian, Jianguo(PRC-XIAM-SM); Zhang, Fuji(PRC-XIAM-SM): On the number of Kekulé structures in capped zigzag nanotubes. (English summary). - J. Math. Chem. 38 (2005), no. 2, 233--246.Sandi Klavžar, 2006, review, book review, critique Keywords: matematika, kemijska teorija grafov, Kekuléjeve strukture, popolno prirejanje, mathematics, chemical graph theory, perfect matchings, Kekulé structures, capped zigzag nanotubes, chemistry
Published in DKUM: 10.07.2015; Views: 1154; Downloads: 42
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7. Alignment of carbon nanotubes in nematic liquid crystalsPaul van der Schoot, Vlad Popa-Nita, Samo Kralj, 2008, original scientific article Abstract: The self-organizing properties of nematic liquid crystals can be used to aligncarbon nanotubes dispersed in them. Because the nanotubes are so much thinner than the elastic penetration length, the alignment is caused by the coupling of the unperturbed director field to the anisotropic interfacial tension of the nanotubes in the nematic host fluid. In order to relate the degree of alignment of the nanotubes to the properties of the nematic liquid crystal, we treat the two components on the same footing and combine Landau-deGennes free energies for the thermotropic ordering of the liquid crystal and for the lyotropic nematic ordering of carbon nanotubes caused by their mutually excluded volumes. The phase ordering of the binary mixture is analyzed as a function of the volume fraction of the carbon nanotubes, the strength of the coupling and the temperature. We find that the degree of ordering of the nanorods is enslaved by the properties of the host liquid and that it can be tuned by raising or lowering the temperature or by increasing or decreasing their concentration. By comparing the theory to recent experiments, we find the anchoring energy of multiwalled carbon nanotubes to be in the range from 10-10 to 10-7 N m-1.
Keywords: liquid crystals, nematic crystals, molecular dynamics, stability, elasticity, carbon nanotubes
Published in DKUM: 07.06.2012; Views: 2023; Downloads: 88
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8. Memory effects in randomly perturbed systems exhibiting continuous symmetry breakingMatej Cvetko, Milan Ambrožič, Samo Kralj, 2009, original scientific article Abstract: We studied pattern characteristics in randomly perturbed structures exhibitingcontinuous symmetry breaking. A Lebwohl-Lasher-type lattice model was used which described well the onset of orientational ordering of a system of rod-like objects. For example, such systems mimic the orientational ordering tendency in liquid crystals or in an ensemble of nanotubes. We set impurities to impose a random anisotropy type of disorder on the objects. Structural characteristics were studied as a function of concentration of impurities, interaction strength w between impurities and rod-like objects, external ordering strength and history of samples. We showed that the characteristic linear size of patterns and range of ordering strongly depend on the history of samples for weak enough strength w. The two-dimensional and three-dimensional simulations yielded qualitatively similar results.
Keywords: liquid crystals, memory effect, nanotubes, structural order, percolation
Published in DKUM: 07.06.2012; Views: 1757; Downloads: 114
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9. The vibrations of microbeams and nanotubesJurij Avsec, 2011, original scientific article Abstract: Temperature variations can significantly change the dynamic characteristics of macro-, micro- and nano-structures. In the presented article we have studied the microbeams and nanotubes under thermal effects. Microbeams and nanotubes will be very important in the future in the fields of MEMS and NEMS. For the physical explanation of vibrations of nanotubes classical mechanics is valid with some limitations. We have taken into account the influence of thermal force, axial force in rotating shaft and also gyroscopic effect. The effect of temperature-dependent material properties was considered primarily with respect to the temperature variations. On the basis of our analytical model it is possible to determine the vibrational characteristics in a very wide range of temperatures. In the presented paper it is shown for the first time in scientific literature the combined influence of temperature, gyroscopic effects and rotor speeds on shaft and beam vibrations.
Keywords: vibrations of microbeams, vibrations of nanotubes, rotor vibration, thermomechanics, nanomechanics
Published in DKUM: 05.06.2012; Views: 2352; Downloads: 37
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