7th International Conference on Nanomaterials - Research & Application
October 14th - 16th 2015 / Hotel Voronez I, Brno, Czech Republic, EU
Nanofibers are defined as fibres with sub-micron diameter. Due to their thickness they offer extremely large specific surface area. The most frequently mentioned ceramic material with nanofiber morphology is a titanium dioxide. The possibility of industrial use of TiO2 nanofibers is conditioned by a highly efficient continuous production technology. This is allowed by a modified Nanospider device. Titanium tetrabutoxide is used as the spinning solution. After spinning process, the nanofibrous layer consists from a mixture of organic and inorganic material, that’s why a subsequent calcination, where any organic components will be incinerated and pure titanium dioxide fibres with a crystalline structure are obtained, is necessary. In the present work a high resolution scanning electron microscope and X-Ray diffraction were used for the assessment of the structure of resulting TiO¬2 nanofibres.
Fibers prepared by electrospinning have a plenty of extraordinary properties. They have use for many applications across a wide range of fields in medicine and industry, which makes them a useful resource for innovations in various products and technologies. Large specific surface area is main advantage of these fibers. Usually the surface of nano/microfibers is almost smooth. Through the process parameters it is possible to obtain porous surface of individual fibres which leads to the pronounced increase in surface area. Variable technological process in nanofibers production, which allows us to design the shape and form of nanofiber structures upon request. Porous fibers may have a variety of uses in numerous applications because they show even larger specific surface area compared to smooth fibers. One of the possible method to evaluate the increase of the surface area is HR-SEM image analysis. The work demonstrates the usage of method enabling the assessment of porosity contribution to increase of micro/nanofiber surface area.
Fluorescence correlation spectroscopy (FCS) represents one of the most sensitive fluorescence techniques due to single molecule detection. Microrheology serves as a tool to study viscoelastic properties of microenvironment of observed particles. Particle tracking (or video) microrheology has its limitations especially due to the size of the particles. FCS is able to observe single molecules or particles and FCS autocorrelation function can be transferred to mean square displacement (MSD) of the particle. We used 30 nm fluorescently labelled particles to observe the movement of the particles in hyaluronan solutions with different molecular weight and different concentrations. Newtonian fluids were used to check the accuracy of measurements. Calculated MSD corresponded to theoretical values so the FCS method and 30 nm particles could be used to determine viscoelastic properties of non-newtonian fluids. We determined MSD as a function of time in greater extent of time when compared to dynamic light scattering (DLS) method or particle tracking microrheology.
AuNi nanoparticles (NPs) were prepared from HAuCl4 and acetylcetonate Ni(acac)2 by the solvothermal route of wet synthesis in oleylamine at 230C. The hexane suspension and the dry nanopowder of the Au-Ni nanoparticles were prepared. Chemical composition of as-synthesized AuNi NPs was obtained using inductively-coupled plasma-optical emission spectrometry (ICP-OES). The optical properties of nanoparticles were monitored using UV-Vis spectrophotometer. The hydrodynamic size of colloid nanoparticles was measured by dynamic light scattering (DLS). Size and shape of metal core of nanoparticles and morphology of aggregates were investigated by electron microscopy (SEM, TEM and HRTEM). Hydrodynamic size of AuNi NPs measured by DLS was compared with the metallic core size obtained by electron microscopy. The thermal properties of AuNi NPs were evaluated by differential scanning calorimetry (DSC) and temperature controlled X-ray diffraction method (t-XRD). The magnetization curves of the AuNi NPs were measured during the heating procedure up to 400C and cooling to room temperature. The fraction of organic matter was deduced from ICP-OES analysis and compared to TGA mass loss. The morphology of aggregate was observed as well as the phase transformation that undergoes at heating (t-XRD, DSC). The experimentally observed information on AuNi NPs was compared with the predicted phase diagram, which was obtained by CALPHAD approach respecting surface energy of the AuNi alloy.
Surface effects on bimetallic nanoparticles have been studying by Knudsen effusion mass spectrometry during slow heating by our research team for two years and this issue is a spontaneous continuation. This time we focused our attention on two Ag-Cu nanoparticle systems. Nanoparticles were synthesized in aqueous and non-aqueous environment and as a protective capping agent against nanoparticle coagulation polyvinyl alcohol and oleylamine were used. As follows from the measurements, the capping agent is quantitatively evaporated at elevated temperatures during the heating process. The other trend, which can be observed, is its simultaneous oxidation. A careful comparison of the measurements for both systems is performed and the results are summarized and discussed in view of previous studies. Study of surface processes is useful for understanding thermal stability and nature of nanoparticle systems.
We report on the formation of Schottky nanocontacts on wide bandgap semiconductors by the conductive tip in atomic force microscope. In-house developed electronics was incorporated in a commercial AFM/STM Veeco Multimode microscope to measure the current-voltage characteristics with PtIr-coated Si and Pt cantilevers. Ga+ focused ion beam and surface chemical treatments were applied to investigate their impact on the properties of nanoscale Schottky contacts on ZnO and GaN. The understanding of the electric charge transport at the nanoscale is essential for the application of semiconductor one-dimensional nanostructures. This work has been supported by the Czech Science Foundation project 15-17044S
In this paper, magnetic properties and interparticle magnetic interactions of the powder mixtures consisting of a ferromagnetic magnetite (mean particle size about 50 nm) and diamagnetic MgO (micrometric particles) are presented. Mixtures with concentrations of Fe3O4 from 10 to 80 wt. % were prepared using two methods: ultrasonic homogenization and manual mechanical mixing. Additionally, the powder mixtures were mechanically pressed in a specially developed device to produce samples in form of pills with the diameter of 10 mm. An EV9 MicroSense vibrating sample magnetometer (VSM) was used for measurements of the virgin curves and magnetization loops. Both measured quantities were used for construction of the Henkel plots that indicate the behavior of the magnetic interparticle interactions of prepared samples. We have discovered that the sample with 30 wt. % of Fe3O4 exhibited the most intensive interparticle interactions and at the same time the highest value of the remnant and saturation magnetization.
Light amplification by stimulated emission of radiation (laser) is a coherent and monochromatic beam of electromagnetic radiation that can propagate in a straight line with negligible divergence and occur in a wide range of wavelength, energy/power and beam-modes/configurations. As a result, lasers find wide applications in the mundane to the most sophisticated devices, in commercial to purely scientific purposes, and in life-saving as well as life-threatening causes. In the present contribution, we provide an overview of the application of lasers for thermal protection from the laser irradiation for protective clothing. In this paper, the impact of laser irradiation on aerogel particles in granular form which is embedded between glass and kevlar fabric was studied. 150 Flexi Marcatex laser instrument was used for this experiment with the new experimental set-up. The different mass of the aerogel was sandwiched between the glass and kevlar fabric to see how it resists the thermal radiation from laser rays. The surface temperature of kevlar fabric was recorded from the backside and was very obvious from the results that the surface temperature of kevlar fabric decreased with the increase in mass of aerogel. All data were statistically analysed in Matlab and Linear fit model was plotted with residuals to see the difference from observed and the fitted data.
Dendrimers are highly branched cascade polymers with regular structure which have been received by regular synthesis and related to a new class of polymer materials called «macromolecular nanoobjects». Dendrimers have been widely and successfully applied to fields of catalysis, medicinal chemistry, and nanotechnologies.
The investigation of standard thermodynamic properties of carbosilane dendrimers with different terminal groups in a wide temperature range by precision adiabatic calorimetry (AC) and DSC allows us to determine and analyze their dependences on composition and structure. The discovery of structural anomalies for carbosilane dendrimers of lower generations and high-temperature relaxation transitions (“nanosized effect”) for these of higher generations is a significant and important result of the calorimetric studies.
In this work the standard thermodynamic properties for carbosilane dendrimers of the first-ninth generations with terminal allyl and butyl groups, some representatives of carbosilanecyclesiloxane dendrimers as well as fluorine contain carbosilane dendrimers high generations were determined in the range 6–650 K by AC and DSC. So, the temperature dependences of heat capacity, temperatures and enthalpies of physical transformations were detected and the values were discussed. The effect of the composition of the dendrimers under study on their thermodynamic properties was considered. For example, the regularities of changing the thermodynamic properties of these compounds on their generation number and molecular mass were detected.
The constituent groups of the dendrimers were selected and isotherms of the dependence of the thermodynamic functions of the dendrimers upon the number of these constituents groups, described with straight lines, were chosen.
Polyaromatic hydrocarbons are water and food pollutants of high concern. They are formed during incomplete oxidation of organic matter, and usually comprise the complex mixture of isomers. Rapid and reliable detection of polyaromatic hydrocarbons is needed to ensure the water and food safety.
Mixtures of polyaromatic hydrocarbons can be separated by thin layer chromatography – a cheap and robust analytical method. However, even if all the required standards are available, identification of different polyaromatic analytes only by their Rf values may be erroneous. Recently, hybrid thin layer chromatography – surface enhanced Raman spectroscopy (TLC-SERS) approach was successfully employed for the detection of ephedrine (DOI:10.1007/s00216-014-8380-9), Sudan I (DOI:10.1016/j.talanta.2015.05.003), and pesticides (DOI: 10.1016/j.talanta.2014.03.075). SERS fingerprints allow to identify the pollutants without the external or internal standards, thus improving the reliability of detection and excluding the need to keep highly toxic compounds at hand to perform the analysis.
In our work we obtain normal Raman and SERS spectra of polyaromatic hydrocarbons, either on reference aluminum foil substrates or directly on TLC plates. Relative simplicity of polyaromatic hydrocarbons opens the possibility to assign the bands in SERS spectra, and to discriminate analytes not only by known fingerprints, but by SERS spectra-based guesses for the unknown compounds.
ACKNOWLEDGEMENTS:
This work was supported by Russian Fund for Basic Research (grant 15-33-21069\15).
Conformational changes of humic acids in different aqueous solutions were studied by means of two novelty methods: high resolution ultrasound spectrometry (HRUS) and micro-rheology (R). Obtained results were compared with those of more coventional method of dynamic light scattering (DLS).
The HRUS method is based on the measurement of parameters of ultrasonic waves propagating through the sample. The attenuation describes the decay of the amplitude of the ultrasonic wave with the distance travelled. The velocity is the speed of this wave and is related to the wavelength and the frequency of oscillation of the deformation. It is determined by the density and elasticity of the sample, which is strongly influenced by the molecular arrangement. The R technics (in contrast to conventional rheology) relies on tracking the motions of the micro-sized tracer particles embedded in the sample. It can give information about a local inhomogeneity especially in the ultra-small scale materials.
Our results showed that the organization of particles in diluted and concentrated solutions of humic acids is different. The conformational arrangement was strongly influence both the concentration and the character of surrounding medium. The decrease in compressibility indicated the formation of a more rigid structure, which could lead to the decrease in the binding ability of humic acids. Changes in sizes of particles detected using DLS resulted in their different mobility and obtained micro-rheological parameters. It was confirmed that both novelty methods employed were very sensitive and could be utilized as indicators of conformational changes in humic systems.
A variety of metal reducing microbial tissues is known, under investigation and some already applied to harvest metals from their natural minerals. Microorganisms also possess the ability to produce well-designed catalysts with attractive properties due to nanoscaled materials with defined shape and composition including a protective coating by a one step procedure.
The comprehensive characterization of the latter material is a great challenge because of the complex matrix concerning the cultivation and the microorganisms itself. Well-known methods for the investigation and analytics on nanomaterials can be destructive to the gained catalyst and their surrounding material. Approaches to handle the characterization of bio-Pd-nanoparticles, analysis of their organic coating and studies to understand their stabilization mechanism will be shown in this presentation. Nanoparticle suspensions obtained from Shewanella oneidensis and by classical colloidal synthesis have been comparatively investigated using TEM, XRD, XPS, DLS, IR, NMR and Zeta-Potential measurement vs. pH.
Microbially produced noble metal catalysts show a remarkable similarity to their chemical analogues and can be a cost-efficient alternative without the usage of effective but toxic reducing reagents like boronhydrids. They have a great potential for electrochemical energy conversion or as catalyst in synthetic organic chemistry, depending on their elemental composition. The performance of the bio-Palladium-catalyst in an environmental relevant application, due the power in the dechlorination of persistent organic pollutants, has been already tested.
The aim of this work was study molecular and quantitative analysis of metal ion binding to humic acids (HAs). The object of our study were two various samples of HAs. HAs were isolated from South-Moravian lignite from the mine Mír (locality Mikulčice, Czech Republic) and compost which was obtained from the composting plant in Náměšť n. Oslavou, Czech Republic. Isolation of HAs was performed according to the procedure recommended by the International Humic Substances Society (IHSS). The reactivity (thermodynamics) of humic acids (HAs) and metals was studied by isothermal titration calorimetry (ITC). As model metals were chosen Cu (II) and Pb (II) ions. ITC was observed reaction enthalpy, Gibbs energy, enthropy and the amount of metal bound to a specific humic acid. The HAs were characterized and compared using spectroscopic techniques, including FTIR and liquid-state 13C NMR spectroscopy. Infrared spectroscopy is a useful technique in characterization of structure, functional groups and formation modes of HAs. 13C NMR spectra of HAs were obtained with a Bruker Avance III NMR spectrometer. For data analysis, the spectra were divided into chemical shift regions assigned to the following classes of chemical groups: alkyl C (0–45 ppm), O-alkyl C (45–106 ppm), aromatic C (106–165 ppm), and carbonyl and carboxyl C (165–220 ppm), respectively. Aromaticity (fa), hydrophilicity and hydrophobicity ratio (Hfi/Hfo) and biological activity (BiA) of HAs were calculated from the area of the NMR spectra.
The application of various nanoparticles expands abundantly in the last period. Nanoparticles are very famous in analytical chemistry but also in physics, biology and medicine. The most commonly used nanoparticles are gold nanoparticles (AuNP) and silver nanoparticles (AgNP). Second important group are colloidal semiconductor particles based on quantum dots (QD’s) effect. The most often used QD’s are soluble cadmium compounds of CdX formula (X = S, Se, Te). The solubility of these compounds can be increased covering the surface by organic compounds containing a thiol group (e.g. mercaptopropionic acid (MPA), glutathione (GSH) or L-cysteine (Cys)) wheretheir carboxyl group could ionize in a certain range of pH and thus the solubility of QD’s nanoparticles is increased. Their exceptional physico-chemical and optical properties as well as higher photostability compared with organic fluorophores can be used for development of new analytical methods for the detection and determination of ions and biologically and medically important molecules. This paper deals with application of QD-CdTe nanoparticles for analytical determination of Cu(II) and Pb(II) ions by means of laser-induced luminescence spectroscopy.
Raman spectroscopy is a commonly used analytical technique for identification of vibrational modes in molecular systems. It provides a fingerprint, by which specific molecule(s) can be identified. Raman spectroscopy can be performed at microscopic level using a Raman microscope by collecting spectra from a very small volume with lateral spatial resolution below one micron that is limited by light diffraction. In this contribution, we deal with Raman imaging. In the case of standard Raman microscopy, this technique is employed for examination of samples to obtain a 2D map of a small range of Raman shifts (direct Raman imaging) or thousands of spatially resolved Raman spectra from all over the field of view (hyperspectral imaging). Similar information can be obtained by using point illumination (e.g. in confocal configuration) and stage scanning.
The goal of this work is to present a way of construction of a low-cost Raman microscope and its combination with large area scanning probe microscopy [1], which enables creation of 2D multispectral high accuracy Raman images. Moreover, the correlative AFM-Raman imaging enables the user to get more information from one specific large area of interest. In contrast to commercial systems our positioning system is traceable to primary standards of length and is able to perform measurements with higher spatial accuracy.
REFERENCES:
[1] Klapetek, P., et al. "Large area high-speed metrology SPM system.", Nanotechnology 26.6 (2015): 065501.
Carbon nanostructure materials have been extensively studied and found application in a wide range of science and engineering since the moment of their discovering. Carbon nanostructures such as nanodiamonds have unique structure. Nanodiamonds are chemically well-defined, and of high purity. Nanodiamonds are likely to share some of the unique properties of macroscopic diamond that are very attractive for a number of applications. The positron annihilation spectroscopy (PAS) is unique method for characterization of defects and pores of carbon nanostructure materials [1, 2].
As a source of the positron isotope 44Ti with the activity of 24.5 µCi was chosen. The 44Ti was placed between two copper capsules filled the compacted carbon powder. The method based on the interaction of positrons with electrons of sample. The time resolution of the system was 260 ps. The full information about spectrometry complex was presented at the article [3]. As the results of experiment the data about positron lifetime in compacted carbon powder and annihilation line Doppler broadening were taken.
REFERENCES:
1. A. Budziak, J. Dryzek, J. Krawczyk, P.M. Zielinski, Acta Physica Polonica A (2012) 117, 574.
2. K. Chakrabarti, P.M.G. Nambissan, C.D. Mukherjee, K.K. Bardhan, C. Kim, K.S. Yang, Carbon (2010) 44, 948.
3. R.S. Laptev, Y.S. Bordulev, V.N. Kudiiarov, A.M. Lider, G.V. Garanin, AMR (2014) 880, 134-140.
We present design and performance of our custom built metrology scanning probe microscope. The device is a national standard for nanometrology and is located in Czech Metrology Institute, regional branch Brno. The main idea for construction of such a device was to have a clear traceability chain and to overcome limitations in accuracy of commercial SPMs. The most critical component in our system is the 3D stage the position of which is monitored using six independent interferometers allowing for compensation of parasitic rotations in all three axes.
In our contribution we discuss the design of main components of the device and demonstrate that it is capable of resolving individual atomic steps on Si (111) surface having size of 0.3 nm.
In the last decades surface-enhanced Raman scattering (SERS) was investigated on the numerous gold and silver substrates including aggregated nanospheres, nanorods, nanostars, nanotubes and so on. Size and shape of the nanostructures used as the SERS substrate determine the enhancement factor of SERS and the spectral range in which SERS can be excited.
In our previous work, metal-halloysite SERS substrates were prepared by vacuum evaporation of different metals [Vinokurov et al., 2015. DOI: 10.1007/s11837-015-1494-5].
In this study, we have developed a SERS substrate by adsorption of gold nanostars on amino and mercapto-modified halloysite nanotubes. This substrate has several advantages: SERS performance is achieved not only by the surface roughness, but also by the hot spots between the particles close to each other, between the branches of nanostars and on the branches’ tips. Additionally, wet chemistry methods used for creating the SERS substrate are cheap and widely available. The gold nanostars were synthesized by method of Cheng et al., 2012 [DOI:10.1039/C1JM13937A]. As revealed by UV-Vis-NIR spectroscopy and transmission electron microscopy, the nanostars are unstable and change within few minutes to the spherical shape. In order to obtain the stable SERS substrate, the nanostars have to be stabilized, but without changes in their SERS activity.
It was found that the gold nanostars adsorbed on the modified halloysite nanotubes keep the initial shape and SERS activity. Nanostars-halloysite SERS substrates do not agglomerate, and could be concentrated or dried without loss of their useful properties.
ACKNOWLEDGEMENTS:
This work is supported by Ministry of Science and Education of Russian Federation (project 16.1812.2014/K)
Growing interest to characterization of nanoparticles (NPs) requires the development of advanced measurement techniques. Surface plasmon microscopy appears as a perfect tool for concentration analysis and study of binding processes. The method is based on the phenomenon of the surface plasmon resonance in a thin gold layer being illuminated by a laser light. A gold coated prism builds a face of a flow cell. Under resonance conditions the sensor layer effectively absorbs the light energy and surface plasmons are excited. NPs bound to the sensor interact with surface plasmons. That leads to the light emission, which is detected by a CMOS camera. If the NPs are sticking to the sensor at the first contact, the concentration of NPs in suspensions can be derived from the binding rate using a theoretical mass transport model. Binding rate measurements allow extracting information about NP binding mechanisms on the base of extended models.
The images measured using Scanning Thermal Microscopy (SThM) depend on both the thermal conductivity and surface topography of the sample. Commonly, the main goal of the measurement is to the study the material properties regardless of the actual surface morphology. The interaction between the tip and the sample leads to a certain value of thermal resistance at each given pixel. In order to understand the heat flow and further analyze the material properties the Finite Element Method has been used for modelling the measurement process. The geometry of the model comes from the topography channel or from the known pattern of the sample. This approach has been used to estimate the thermal conductivity of multiwalled carbon nanotubes (MWCNT's). There are three objects involved in the model - the tip, the carbon nanotube and the substrate. Still, there are unknown thermal contacts between all these objects and the simulation leads to rough estimation of the heat flow and thus some quantification of the carbon nanotube's thermal conductivity is calculated.
Scanning probe microscopy (SPM) belongs between most frequently used characterisation techniques for nanoscale topograhy of solid surfaces, including mapping of different physical quantities (electrical, thermal magnetic or optical properties). Present SPMs are capable to measure with sub-nanometer resolution, nanometer accuracy and in range up to few hundreds of micrometers; in special devices even in range up to millimeters. Even if the combination of large scanning range and high accuracy seems to be very attractive, SPMs are still considered as slow instruments comparing to other imaging techniques and such high spatial density measurements are even much slower. A solution is to measure with high data density only on sample areas that contain
information necessary for particular quantities that should be evaluated and to use low data density in all the other parts. To do this, we need to change the way how the data are acquired and how they are processed afterwards. We present an approach covering both these steps, forming an open source library for non-equidistant scanning, data previewing, storage and processing. During development we concentrated on library portability, applicability on different hardware and software platforms. Examples of library use on both synthetic and real data will be presented to show the SPM performance improvements.
New materials with high possible figure of merit ZT are of high interest as a promising candidates for thermoelectric applications such as energy harvesting. Miniaturization of such systems tend toward developing of the suitable characterization method with nanometer resolution ability. In our contribution, we present the development and experimental results of a simple scanning probe microscopy method for the relative thermal conductivity characterization. The possibility of the setup is demonstrated on the set of different thin thermoelectric layers grown from hot pressed targets by pulsed laser deposition on the reference Si substrate. All the measurements were performed on the commercial Veeco Multimode scanning AFM/STM microscope with home developed controller and by using PicoCal Inc. bolometer probes with tungsten resistive path. All the experiments were done in the air at the ambient condition. Additional sample treatment for the measurement will be also briefly described.
ACKNOWLEDGEMENTS:
The project has been supported by Czech Grant Agency under P108/13-33056S.
Last few decades have established the atomic force microscope (AFM) as an indispensable tool for high-resolution studies under native conditions. Recent tip-scanning AFM developments now offer an insight into the dynamics of macromolecular systems, while simultaneously offering a seamless integration with advanced optical microscopy.
In this study, we non-invasively monitor and modify the kinetics of collagen type I fibrillogenses. Collagen type I has received a lot of attention over the last five decades, due to their large interactome, hierarchical structural and mechanical stability. We show that fast AFM imaging can be successfully applied to understand the real-time kinetics of collagen type I formation. By further modifying the used buffer compositions, pH value and potassium ion content, we demonstrate that we can accelerate the kinetics of the fibrillar nanomatrix formation and successfully study it with high spatial and temporal resolution.
Additionally we show the capability of combining AFM with super-resolution techniques to demonstrate the relation of cytoskeleton distribution and mechanical properties of HeLa cells. Alexa647 labeled microtubules are imaged with dSTORM, while the cell surface and mechanical information are measured in parallel by AFM.
The Finite Element Method (FEM) and its variants have been in use for mechanical modelling for a long time, even at micro- and nanoscale. Due to its principles, standard FEM is not convenient for problems involving large deformations of the material or presence of cracks and discontinuities. In recent decades, extensions of FEM have been developed to better cope with such difficulties, and new methods based on different methodologies have been introduced, with the Material Point Method (MPM) being one of them.
Using an open-source MPM engine, we will demonstrate application of the method to some problems of common interest and investigation, such as beam bending (used to determine properties of AFM cantilevers), nanopillar compression and nanoindentation.
The control of thermal transport is essential for many modern nanomaterials and necessary for the new generation microelectronics devices. The study and understanding of the heat flow across the nanomaterials is the main priority for the large spectrum of microelectronic industries. Unfortunately, quantitative measurements of thermal properties at nanoscale are still problematic, even with use of advanced techniques like Scanning Thermal Microscopy. Therefore, the molecular dynamics simulations can be helpful for the better description of thermal transport processes inside of nanomaterials.
This contribution represents the equilibrium molecular dynamics simulation (Green-Kubo relation) to predict the thermal transport properties (especially thermal conductivity) of nanomaterials. We focused on semiconductors (silicon) and insulators (diamond and polyethylene) and showed the difference between real and simulated value of thermal conductivity in dependence on temperature. Moreover, the effect of various inter atomic potentials (force fields) on the value of thermal conductivity was studied.
Nature and natural systems represent from the beginning of human being magnificent source of both basic raw materials as well as of an inspiration for majority of human driven processes and applications. Biopolymers, representing substances with indispensable role in natural ecosystems, can be listed as the proper example. One of the most important parameter of these substances is their stability, which nowadays still lacks for deeper research. The main aim of this work was to shed a new light on the area of natural substances ongoing aggregation and degradation processes especially in longer time scale. Even slight deviation of these natural substances, which are often used in industrial processes, as final products for distribution to customers or just in long-term research, can cause serious problems (e.g. different yield of product, bad purity or unfavourable property of obtained product, wrong directing of research…). All these effects are of course highly undesirable. This work is mainly focused on the optimization and deeper research on biopolymers stability using light scattering techniques. For purposes of experimental work the system of SEC-MALS was applied as crucial method providing the information about changes in molecular weight and particle size. Results were also compared and correlated with subsequent determination of particle size by means of dynamic light scattering and zeta potential using electrophoretic light scattering. The obtained experimental results showed good correlation between individual light scattering techniques and proved suitability of all presented light scattering methods for the purposes of biopolymers stability research.
Self-assembly techniques attracted a lot of interest in recent years due to its ability to form number of periodic surface patterns over large areas. This process is fast, very efficient and cost effective. By modifying surface pattern we can optimize polymer for specific use, from optical devices through particle sorting to flexible electronics. Today`s main challenge is find suitable materials capable of self-assembly and study how we can influence surface pattern to achieve best results.
In our work, we used formation of ripple-like patterns by wrinkling instability of poly-L-lactic foil with gold nanostructure initiated by annealing. Resulting structures showed significant degree of morphological orientation observed by atomic force, which in optimized cases resulted in electrical anisotropy. This reorganization of conductive gold on insulating polymer into metal nanowires can be also observed by zeta-potential measurements. Due to poly-L-lactic acid being biopolymer, these samples were also tested for cytocompatibility. NIH 3T3 fibroblasts were used and selected samples showed significantly higher adhesion and proliferation in comparison with PS mock.
Our department has been studying high-current capillary discharge as a prospective XUV laser source since 1998. Among others we have built two experimental apparatuses CAPEX (since 1998) and CAPEX-U (since 2005). On both these devices we have observed lasing at 46.9 nm (Ne-like argon line). While the experimental apparatus CAPEX-U has laser-triggered spark gap, which enables exact synchronization with diagnostics or with other attached experiments, the apparatus CAPEX is capable to run at a higher repetition rate (up to ~ 1 Hz).
The experimental results of interaction of focused XUV laser beam (wavelength 46.9 nm) with Polymethylmethacrylate (PMMA) and GaAs samples will be presented. Proximity-standing golden grid showed on naturally-generated diffraction pattern that direct nanostructuring is possible.
Pulsed laser ablation (PLA) is a method that allows obtaining of nanoparticles of different materials – metals, oxides, binary systems, etc. The process of ablation can be performed either in pure liquid, or in the presence of different chemical additives (such as stabilizers, surfactants). In the first case it is possible to obtain “pure” nanoparticles, which is very useful for some applications, for example, in modelling of chemical and physical processes where additives can cause interference. But even in the absence of additional chemicals, nanoparticles can react with the liquid, dissolved gases, with each other. Thus, it is necessary to investigate and control their structure and composition.
Many different analytical methods can give information of structure and composition of obtained nanoparticles, including electron microscopy, X-ray diffraction, spectroscopy, and others. But obtaining of information on objects under study using express, cheap, and sensitive electrochemical methods is of a high interest. This work deals with an attempt of using voltammetry for characterization of nanoparticles. “Pure” nanoparticles of different metals were adsorbed from their dispersions on an indicator electrode, and obtained signals gave the information on studied samples.
ACKNOWLEDGEMENTS:
The work is performed within the state assignment of Russian Ministry of Education and Science (Assignment #2014/223, Project code #1347).
In this study, the structural morphology and magnetic effects of magnetic ZnFe2O4 nanoparticles loaded with the cancer-fighting drug doxorubicin hydrochloride (DOX-HCl) were investigated. These nanoparticles have been found to have potential biomedical applications in targeted drug-delivery systems. The zinc ferrite nanoparticles were prepared by a chemical coprecipitation method and coated with chitosan. The nanoparticles were loaded with DOX-HCl and their surfaces improved by folic acid, which can be activated to target specific cancer cells. The specific absorption rate (SAR) values of the ZnFe2O4-chitosan-DOX-HCl nanoparticles were investigated at a frequency of 200 kHz and 1.5 kA/m amplitude in order to obtain Brownian relaxation time parameters. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and ultraviolet-visible spectrophotometry (UV-Vis) were used to characterize the bulk properties of these nanoparticles. In addition, the impact of the nanoparticles under an alternating current (AC) magnetic field and their heat-generation ability were investigated using an experimental setup. The average nanoparticle size was found to be 8.5 nm. Magnetic hysteresis loops confirmed the superparamagnetism of the nanoparticles. The saturation magnetization was 6 emu/g. UV-Vis was used to measure the amount of drug loaded onto the nanoparticles. The amount of drug absorption was significantly higher after 12 hour, totaling 75%. The specific absorption rate parameter was 80.66 W/g, and the Brownian relaxation time was 188 10–9 s.
Rod-like mesoporous TiO2-SiO2 particles were synthesized by coating of large pore mesoporous silica by a TiO2 layer. First, due to avoid collapsing of pores by TiO2 layer, large pore mesoporous silica by using Hexane as a pore expander was prepared. Then, the synthesized particles were coated with TiO2 by stirring them in a TiO2 solution for 1 hour. The prepared materials were characterized by X-ray diffraction (XRD), Small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and N2 adsorption–desorption experiments. The results show that anatase phase is distributed on the mesoporous SiO2 particles.