Fullerenol nanoparticles as a new delivery system for doxorubicin

Doxorubicin is a very potent chemotherapeutic drug, however its side effects limit its clinical use. The aim of this research was to investigate the properties of a fullerenol/doxorubicin nanocomposite, its potentially cytotoxic and genotoxic effects on malignant cell lines, as well as its toxicity towards zebra fish embryos. Chromatographic, NMR and mass spectral analysis of the nanocomposite imply that interactions between doxorubicin and fullerenol are non-covalent bonds. The stability of the nanocomposite was confirmed by the use of atomic force microscopy, dynamic light scattering and transmission electron microscopy. The nanocomposite, compared to the free doxorubicin at equivalent concentrations, significantly decreased the viability of MCF-7 and MDA-MB-231 cells. The flow cytometry results indicated that doxorubicin-loaded fullerenol could remarkably increase the uptake of doxorubicin suggesting that fullerenol might be a promising intracellular targeting carrier for the efficient delivery of antitumor drugs into tumor cells. The nanocomposite also affected cell cycle distribution. A genotoxicity test showed that the nanocomposite at all examined concentrations on MCF-7 and at lower concentrations on MDA-MB-231 cells caused DNA damage. Consequently, cell proliferation was notably reduced when compared with controls. Results of the zebrafish embryotoxicity assay showed a decreased overall toxicity, particularly cardiotoxicity and increased safety of the nanocomposite in comparison to doxorubicin alone, as manifested by a higher survival of embryos and less pericardial edema

Mechanical and magnetic properties of composite materials with polymer matrix

Many of modern technologies require materials with unusual combinations of properties that cannot be met by the conventional metal alloys, ceramics, and polymeric materials. Material property combinations and ranges have been extended by the development of composite materials. Development of Nd-Fe-B/polymer composite magnetic materials has significantly increased interest in research and development of bonded magnets, since particles of Nd-Fe-B alloys are proved to be very suitable for their production. This study investigates the mechanical and magnetic properties of compression molded Nd-Fe-B magnets with different content of magnetic powder in epoxy matrix. Mechanical properties were investigated at ambient temperature according to ASTM standard D 3039-00. The obtained results show that tensile strength and elongation decrease with an increase of Nd-Fe-B particles content in epoxy matrix. The modulus of elasticity increases, which means that in exploitation material with higher magnetic powder content, subjected to the same level of stress, undergoes 2 to 3.5 times smaller deformation. Scanning Electron Microscopy (SEM) was used to examine the morphology of sample surfaces and fracture surfaces caused by the tensile strength tests. The results of SQUID magnetic measurements show an increase of magnetic properties of the investigated composites with increasing content of Nd-Fe-B particles

Analiza formiranja PVB-SiO2 nanokompozitnih vlakana pomoću elektrospining procesa

The poly (vinyl butyral)-silica (PVB-SiO2) nanofibers were obtained by the electrospinning process. The experiments were carried out with PVB solution in concentration of 10 wt.% where ethanol was used as the solvent. The silica nanoparticles were added in the solution in different contents of 1, 3 and 5 wt.% SiO2 and nanoparticles were modified with γ-aminopropyltriethoxysilane (AMEO silane). The impacts of the parameters of the electrospinning process and the silica nanoparticles on the produced PVB-SiO2 nanocomposite fibers were tested. The structures of the PVB-SiO2 nanocomposite fibers were investigated using optical microscopy and scanning electron microscopy (SEM). The morphology and distribution of the resulting nanofibers were analyzed using the software Image-Pro Plus. .Poli (vinil butiral)-silika (PVB-SiO2) nanovlakna su dobijena metodom elektrospininga. Eksperimenti su izvedeni u rastvoru 10 mas.% PVB-a u etanolu koji je korišćen kao rastvarač. Nanočestice silike su dodate sa različitim sadržajem od 1, 3 i 5 mas.% SiO2 i modifikovane γ-aminopropiltrietoksi silanom (AMEO silanom). Istražen je uticaj procesnih parametara elektrospininga na nanokompozitna vlakna PVB-SiO2. Struktura PVB-SiO2 nanokompozitnih vlakana je proučavana pomoću optičke mikroskopije i skenirajuće elektronske mikroskopije (SEM). Morfologija proizvedenih nanokompozitnih vlakana i njihova raspodela je analizirana u Image Pro Plus softveru.

A novel approach to modeling and simulation of NTC thick-film segmented thermistors for sensor applications

This paper describes the design, modeling, simulation, and fabrication of thick-film segmented thermistors. These thermistors were printed on alumina using negative temperature coefficient 3K3 paste, composed of nanometer powder. Their room temperature resistance was measured versus the number of segments and electrode surface value for the fixed layer thickness and electrode spacing. After that, very large thermistors were printed to serve as both the powerful self-heaters and the heat loss sensors in the thermistor volume air flow meter and anemometer. For an application in AC bridges, impedance Z(f) and insertion loss S21 [dB] of the same largest segmented thermistor were measured using network analyzer HP8752A. Impedance modeling was performed using simple equivalent electrical circuit with circuit parameters estimated by fitting procedure (traditional approach), as well as using a commercial electromagnetic simulation program microwave office (MWO, novel approach). This was followed by the modeling of electrical current distribution over a number of segments done within the MWO. The results obtained from simulations and measurements were mutually compared

Procesiranje i nanomehanička svojstva filma blendi hitozan/polietilen-oksid

Chitosan-based films have found increasing implementation in a variety of fields, among which are as drug delivery carriers, in the packaging industry and as water purification filters. Therefore, in order to achieve mechanical integrity of such films while preserving processability and biocompatibility, chitosan-based films are fabricated in the forms of blends with poly(ethylene oxide) (PEO). A nano-indentation study was undertaken in order to investigate the nanomechanical properties and surface morphology of chitosan films in blends with various content of PEO. The results of differential scanning calorimetry, water uptake and nano-indentation revealed that films with an 80/20 blend ratio of chitosan/PEO showed the optimal values of reduced modulus and hardness. It appears that the incorporation of the synthetic PEO in chitosan films could lower the manufacturing costs while preserving the mechanical integrity of the films.Filmovi na bazi hitozana nalaze sve širu primenu u raznim oblastima između ostalog kao nosači lekova, u industriji ambalaže i kao filteri za prečišćavanje voda. Da bi se postigao mehanički integritet ovakvih filmova i zadržala procesabilnost i biokompatibilnost, filmovi na bazi hitozana pripremljeni su u formi blendi sa polietilen oksidom (PEO). Studija nanoindentacije urađena je u cilju proučavanja nanomehaničkih svojstava i površinske morfologije hitozanskih filmova u blendama sa različitim sadržajem PEO. Rezultati DSC-a, apsorpcije vode i nanoindentacije pokazali su da filmovi blendi sa odnosom 80/20 hitozana i PEO poseduju optimalne vrednosti redukovanog modula elastičnosti i tvrdoće. Pokazano je da dodavanje sintetičkog PEO u hitozanske filmove može smanjiti cenu proizvodnje i istovremeno zadržati mehanički integritet filmova

Whitening-dependent changes of fluorescence of extracted human teeth

Objective: To evaluate in vitro the fluorescence properties of extracted human teeth whitened with 40% hydrogen peroxide. Materials and Methods: A total of 28 extracted human teeth were pumiced for 1 minute using a low-speed dental handpiece and a disposable rubber cup. Pre-whitening fluorescence measurements (T0), maximum excitation (Ex(max)), maximum emission (Em(max)), and maximum intensity (I(max)10(8)), were performed using a spectrofluorometer. After T0 measurements, the teeth were whitened using the in-office method with 40% hydrogen peroxide, three times for 20 minutes. The fluorescence parameters were measured under the same conditions 7 and 14 days after bleaching (T1 and T2, respectively). Results: Ex(max) exhibited a broader range 7 days after whitening and decreased after 14 days. The Em(max) and I(max)10(8) displayed a narrower range after whitening. The mean Ex(max) differed significantly between the time points (F = 20.09. P LT .001). The corresponding analysis for the mean Em(max) differed significantly between the time points (F=16.69, P LT .001). The same was true for the mean I(max)10(8) (F = 9.69, P LT .001). Conclusions: Within the limitations of this study, whitening provoked statistically significant changes in fluorescence of the intact teeth in vitro

Improved Model of T-Type LC EMI Chip Filters Using New Microstrip Test Fixture

In this paper we present an improved model of the multilayered T-type electromagnetic interference chip LC filter for printed circuit board applications, and an improved measurement technique for characterization of such devices. Electrical parameters measurements of the same LC filter can vary for different measurement types. Because of that, we have developed new adaptation microstrip test fixture on printed circuit board for vector network analyzers' measurements of surface mount devices with three terminals. Two commercially available components, multilayer T-type LC filters, are measured and characterized using a vector network analyzer. The comparison of measurement data and simulation values of electrical equivalent circuit and electromagnetic model for two LC filters is further presented. The new improved model of T-type LC filters has provided better agreement between measurement and simulation

EM Simulator Analysis of Optimal Performance Thick-Film Segmented Thermistors versus Material Characteristics Selection

In this paper, an alternative approach to the analysis of thick-film segmented negative temperature coefficient thermistors based on the use of a commercial electromagnetic simulator tool is presented. The influence of the geometrical parameters and material characteristics of the used thermistor paste on the overall thermistor performance was analyzed and simulated. A physical model for the segmented thermistors is given in brief, together with experimental data. The diffusion of electrode metal into the thermistor layer was analyzed, simulated, and estimated. Obtained simulation results were compared with experimental results, and the validity of the adopted approach was verified