Biodegradation of nanoparticles includes the destruction of a stabilizing coating and the accompanying change in interparticle interaction, as well as the direct destruction of the inorganic nuclei of particles. These processes lead to characteristic changes in the shape of the Mossbauer spectra of iron oxide nanoparticles. In this work, we investigated the in vitro biodegradation of Fe-57-based magnetic nanoparticles with the aid of Mossbauer spectroscopy. For this purpose, two types of magnetic nanoparticles enriched with the Fe-57 isotope were synthesized. Copolymer Pluronic F-127 and citric acid were used to stabilize nanoparticles in aqueous medium. Moreover, synthesized nanoparticles were analyzed by physicochemical methods and investigated for cytotoxicity. The study of magnetic nanoparticles biodegradation was performed on 4T1 cell culture (breast cancer). We measured Mossbauer spectra of nanoparticles incubated with 4T1 cells and spectra of control nanoparticle samples at different conditions. The analysis of spectra was carried out in the many-state relaxation model formalism. The study revealed that after 120-hours incubation of nanoparticles in cells, they did not undergo measurable changes typical of biodegradation processes. Nevertheless, we noted intense intracellular oxidation of ferrous iron of synthesized nanoparticles to the ferric phase. The results obtained indicate the possibility of using the obtained nanoparticles in Mossbauer in vitro studies.

In this work was proposed a new radiotherapy enhancement method consisting of the administration of magnetic nanoparticles into the cells with further irradiation with a gamma-ray beam. As a result, adjusting the energy distribution of a gamma-ray beam and 57 Fe abundance it is possible to achieve an extremely intensive electron emission because of a nuclear resonance. The produced conversion and Auger electrons can be used as an effective tool for DNA lesions production. We developed a Monte Carlo model for an electron and gamma emission by 57 Fe nucleus using the Geant4 program package. The parameters of a resonant absorption were taken from Mössbauer spectra of magnetite nanoparticles synthesized for the administration into live cells. The space distribution of the radiation dose showed an increase in the dose of 2–2.5 times in the case of the natural abundance and more than 50 times in the case of the 66 % enrichment of the nanoparticles.

Mössbauer spectroscopy in a weak static magnetic field and measurements of isothermal magnetization loops were used to study the effect of polymer coating of the γ-Fe 2 O 3 nanoparticles on the magnetic properties of concentrated ensembles of such nanoparticles. It was found that the individual coating of the nanoparticles by a ∼ 1 nm layer of the polymer leads to the observable changes in the shapes of the Mössbauer spectra and the magnetization curves of the ensembles. Modeling of the experimental magnetization curves in the classical Langevin model and analysis of the Mössbauer spectra in the generalized multi-level relaxation model revealed that the establishment of interparticle magnetic dipole interactions leads to both a ∼ 30 % increase in the magnetic anisotropy constant and a ∼ 35 % increase in the width of the hysteresis loop.

A theoretical analysis has been made and calculation procedures have been developed for describing the hyperfine structure of 151Eu Mössbauer spectra and the effect of double optical-gamma resonance (DOGR) in the presence of hyperfine quadrupole interaction with an arbitrary symmetry of the electric field gradient tensor. An experimental setup was designed for DOGR-effect observation, incorporating the pumping argon laser and the tunable dye laser combined with the Mössbauer spectrometer on a common platform. The Mössbauer absorption spectra of 151Eu3 +  nuclei in single crystals of europium pentaphosphate, EuP5O14, have been measured at T = 5 K and 80 K under the absence and presence of optical pumping tuned to the 7F\(_{0}-^{5}\)D0 electronic transition at the 578 nm wavelength. A simultaneous analysis of these spectra in terms of the spin Hamiltonian of hyperfine quadrupole interaction has allowed us to evaluate the DOGR-effect magnitude with the population of the excited (5D0) electronic state under optical pumping of about 10 %.

The ferrofluid, based on 57Fe isotope enriched Fe3O4 nanoparticles, was synthesized, investigated by Mössbauer spectroscopy method and injected transcranially in the ventricle of the rat brain. The comparison of the Mössbauer spectra of the initial ferrofluid and the rat brain measured in two hours and one week after the transcranial injection allows us to state that the synthesized magnetic 57Fe3O4 nanoparticles undergo intensive biodegradation in live brain and, therefore, they can be regarded as a promising target for a new method of radionuclide-free Mössbauer brachytherapy.

In order to extract a quantitative information about characteristics of the magnetic nanoparticles injected into a living organism it is necessary to define a model of the magnetic dynamics for fitting self-consistently the whole set of the experimental data, specifically, the evolution of Mössbauer spectral shape with temperature and external magnetic field as well as the magnetization curves. We have developed such a model and performed such an analysis of the temperature- and magnetic field-dependent spectra and magnetization curves of nanoparticles injected into mice. This allowed us to reliably evaluate changes in the characteristics of the residual particles and their chemical transformation to paramagnetic ferritin-like forms in different mouse organs as a function of time. Actually, the approach makes it possible to quantitatively characterize biodegradation and biotransformation of magnetic nanoparticles delivered in a body.

In order to extract quantitative information about characteristics of the magnetic nanoparticles in a media it is necessary to define a model of the magnetic dynamics for treating self-consistently the whole set of the experimental data, particularly, the evolution of Mossbauer spectral shape with temperature and external magnetic field as well as the magnetization curves. We have developed such a model and performed such an analysis of the temperature- and magnetic field-dependent spectra and magnetization curves by the example of nanoparticles injected into laboratory mice. This allowed us to reliably evaluate changes in the characteristics of the residual particles and their chemical transformation to paramagnetic ferritin-like forms in animals organs as a function of time. Actually, the approach makes it possible to quantitatively characterize biotransformation and biodegradation of magnetic nanoparticles delivered in a living organism.

Radionuclidic impurities of 210Po prepared by neutron irradiation of 209Bi via the 209Bi(n,γ)210Bi reaction were investigated. Following irradiation and ingrowth, a pure 210Po solution was obtained by sublimation and dissolution. Results were obtained by liquid scintillation (LS) counting, isotope dilution alpha (α)-spectrometry, and high-purity germanium gamma-ray spectrometry. No alpha-emitting (3–10 MeV) or gamma-emitting (30–3600 keV) impurities were detected, with calculated lower limits of detection for impurities of approximately 0.01% 210Po activity. LS spectra revealed no identifiable beta-emitting impurity. LS sources prepared using Opti-Phase ‘Hi Safe’ III and Opti-Fluor LS cocktails were stable over a 4-day multi-cycle counting period for 210Po dissolved in 0.1% trifluoracetic acid (pH ∼2, water fraction ∼2%). The radioactivity concentration determined by LS counting was verified by isotope dilution alpha spectrometry. These results suggest that neutron irradiation of 209Bi (followed by sublimation) can produce 210Po in a highly pure form that is suitable for radiopharmaceutical preparations.

Purpose: The increasing interest in a homogeneous Gaussian light beam profile for applications in ophthalmology i.g. photorefractive keratectomy (PRK) requests simple optical systems with low energy losses. Therefore, we developed the Light Shaping Beam Homogenizer (LSBH) working from UV up to mid-IR.Method: The irregular microlenses structure on a quartz surface was fabricated by using photolithography, chemical etching and chemical polishing processes. This created a three dimensional structure on the quartz substrate characterized in case of a Gaussian beam by random law distribution of individual irregularities tilts. The LSBH was realized for the 193 nm and the 2,94 mu m wavelengths. Simulation results obtained by 3-D analysis for an arbitrary incident light beam were compared to experimental results.Results: The correlation to a numerical Gaussian fit is better than 94% with high uniformity for an incident beam with an intensity modulation of nearly 100%. In the far field the cross section of the beam shows always rotation symmetry. Transmitance and damage threshold of the LSBH are only dependent on the substrate characteristics.Conclusions: Considering our experimental and simulation results it is possible to control the angular distribution of the beam intensity after LSBH with higher efficiency compared to diffraction or holographic optical elements.

Main specifications and technical solutions of the universal setup for laser assisted chemical vapor deposition are presented.