X-ray photoelectron spectroscopy of hybrid 3T3 NIH cell structures with internalized porous silicon nanoparticles on substrates of various materials

The work is related to the study of a biohybrid material based on mammalian 3T3 NIH mouse fibroblast cells with immobilized porous silicon particles including nanocrystals about 10 nm in size by photoelectron spectroscopy. The influence of the surface material of the substrate on which the biohybrid material is grown on the possibility of conducting studies of the physico-chemical state of the developed surface is studied. Nickel as well as gold and titanium, known for their biocompatibility, were used as surface materials for cell growth and subsequent internalization of silicon particles. The method of optical microscopy in the reflected light mode was used to assess the distribution of cells on surfaces. It is shown that the nickel surface is not suitable for the synthesis and subsequent studies of biohybrid structures. At the same time, on the surface of gold and titanium, cellular material and structures based on it are available for measurements, including by photoelectron spectroscopy, a high-precision method for studying the atoms charge state and the physico-chemical state of the surface as a whole. The X-ray photoelectronic spectra show all the main components expected to be detected after drying and subsequent vacuuming of the studied objects: the surface material of the substrates and arrays of cell cultures grown on the substrates. No signal from silicon atoms was detected on the nickel surface. In the case of a gold surface, the proximity of the binding energies of the gold core levels (substrate) and silicon (internalized particles) leads to the fact that the signal of gold atoms, which is significant in its intensity, does not allow detecting a signal from silicon atoms, which is weaker in intensity. The signal of silicon atoms in biohybrid structures is reliably detected only when using titanium substrates, including for a control sample containing porous silicon nanoparticles without incubation in cells. Thus, it is shown that the surface of the titanium foil can be used for studies by photoelectron spectroscopy of a biohybrid material based on mammalian 3T3 NIH mouse fibroblast cells with immobilized porous silicon particles.The obtained result is important for high-precision diagnostics of the physico-chemical state of biohybrid materials and structures based on them with a low content of silicon atoms when solving problems of studying the compatibility and possibilities of using silicon nanomaterials for medical, including therapeutic and other applications

Electronic structure and composition of tin oxide thin epitaxial and magnetron layers according to synchrotron XANES studies

The materials of the tin-oxygen system and thin-film structures based on them are modern and actual for the creation of a wide range of electronic devices, for example, resistive gas sensors of high sensitivity and short response time with low energy consumption and high manufacturability. An important direction in the study of such materials and structures is the control of properties with variations in technological formation regimes. Information on the composition, local atomic and electronic structure of thin layers of the tin-oxygen system with varying approaches to their production is in demand. The work is devoted to the study of the electronic structure of thin layers of tin oxides obtained by modern methods of molecular beam epitaxy and magnetron sputtering. A study of the local partial density of electronic states in the conduction band by X-ray absorption near edge structure spectroscopy of tin and oxygen has been carried out. The data were obtained using high-intensity synchrotron radiation, which allows varying the monochromatized radiation quantum energy without loss in intensity, that is necessary to obtain high-resolution X-ray spectral data. It is shown that the composition, local atomic surrounding, electronic spectrum and their features depend on the technology of formation and storage conditions of the studied structures. Synchrotron X-ray spectroscopy data show the presence of intermediate oxides of the tin-oxygen system in the studied materials after prolonged storage in laboratory conditions. The data obtained indicate the possibility of controlled variation in the composition, local atomic surrounding and electronic spectrum of thin-film structures of tin oxides of small thickness. The results of the work can be used in the formation and subsequent modification of thin and ultrathin layers of tin oxides by magnetron sputtering and molecular beam epitaxy, as well as in their further application as active layers of microelectronics device