Vasily Lavrentiev

Tunnel magnetoresistance in Co nanoparticle/Co–C60 compound hybrid system

A nanometer-scale hybrid film of Co particle/Co–C60 compound was prepared by alternate deposition of Co and C60 under UHV condition. All of Raman spectra, magnetization curves, and tunnel conductivity concluded that the hybrid system has a granular structure consisting of Co nanoparticles embedded in a Co–C60 compound matrix. The magnetoresistance ratio of 26% was obtained at 2K and 10kOe for the electron tunneling across the Co–C60 compound barrier. In addition, anomalously large bias voltage dependence was found in the magnetotransport properties.

Growth and Potential Damage of Human Bone-Derived Cells on Fresh and Aged Fullerene C60 Films

Fullerenes are nanoparticles composed of carbon atoms arranged in a spherical hollow cage-like structure. Numerous studies have evaluated the therapeutic potential of fullerene derivates against oxidative stress-associated conditions, including the prevention or treatment of arthritis. On the other hand, fullerenes are not only able to quench, but also to generate harmful reactive oxygen species. The reactivity of fullerenes may change in time due to the oxidation and polymerization of fullerenes in an air atmosphere. In this study, we therefore tested the dependence between the age of fullerene films (from one week to one year) and the proliferation, viability and metabolic activity of human osteosarcoma cells (lines MG-63 and U-2 OS). We also monitored potential membrane and DNA damage and morphological changes of the cells. After seven days of cultivation, we did not observe any cytotoxic morphological changes, such as enlarged cells or cytosolic vacuole formation. Furthermore, there was no increased level of DNA damage. The increasing age of the fullerene films did not cause enhancement of cytotoxicity. On the contrary, it resulted in an improvement in the properties of these materials, which are more suitable for cell cultivation. Therefore, fullerene films could be considered as a promising material with potential use as a bioactive coating of cell carriers for bone tissue engineering.

Growth and Potential Damage of Human Bone-Derived Cells Cultured on Fresh and Aged C60/Ti Films

Thin films of binary C60/Ti composites, with various concentrations of Ti ranging from ~ 25% to ~ 70%, were deposited on microscopic glass coverslips and were tested for their potential use in bone tissue engineering as substrates for the adhesion and growth of bone cells. The novelty of this approach lies in the combination of Ti atoms (i.e., widely used biocompatible material for the construction of stomatological and orthopedic implants) with atoms of fullerene C60, which can act as very efficient radical scavengers. However, fullerenes and their derivatives are able to generate harmful reactive oxygen species and to have cytotoxic effects. In order to stabilize C60 molecules and to prevent their possible cytotoxic effects, deposition in the compact form of Ti/C60 composites (with various Ti concentrations) was chosen. The reactivity of C60/Ti composites may change in time due to the physicochemical changes of molecules in an air atmosphere. In this study, we therefore tested the dependence between the age of C60/Ti films (from one week to one year) and the adhesion, morphology, proliferation, viability, metabolic activity and potential DNA damage to human osteosarcoma cells (lines MG-63 and U-2 OS). After 7 days of cultivation, we did not observe any negative influence of fresh or aged C60/Ti layers on cell behavior, including the DNA damage response. The presence of Ti atoms resulted in improved properties of the C60 layers, which became more suitable for cell cultivation.

Multitarget Sputtering of Piezoelectric Mixed Oxide Thin Films onto Flexible Substrates

Large area film deposition was performed by means of multitarget reactive magnetron sputtering from metallic targets (Pb, Ti, Zr) with a diameter of 200 mm onto Cu-coated Kapton® HN substrates. High-power pulse sputtering has been employed for the Zr-target (or alternatively for the Ti-target). Film composition profiles were evaluated by XPS and RBS. Piezoelectric properties were investigated by PFM.

Multitarget sputtering of PZT-containing mixed oxide thin films onto copper-coated Kapton substrates

Large area film deposition was performed by means of multitarget reactive magnetron sputtering from 200 mm diameter metallic targets (Pb, Ti, Zr) onto Cu-coated Kapton HN substrates. High-power pulse sputtering has been employed for the Zr-target (or alternatively for the Ti-target). Film composition profiles were evaluated by XPS and RBS. Piezoelectric properties were investigated by PFM.

Composition profiling of piezoelectric PZT thin films deposited onto Cu coated polymer substrates

In this work, we investigate the composition profile of nanocrystalline Pb(Zr, Ti)O3 (PZT) thin films deposited by means of reactive magnetron sputtering from 200 mm diameter metallic targets (Pb, Ti, Zr). High-power pulse sputtering has been employed for alternatively the Zr- or Ti-target. Composition analysis and profiling was performed by means of X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering (RBS). RBS data was recalibrated to exclude hydrogen content not determined by XPS. Advantages and drawbacks of both methods for PZT composition profiling are discussed.