Science and research

Ionizing radiation represents one of the major health risks that must be assessed when planning long-term space missions with human crews. Protons are among the dominant components of galactic cosmic radiation and solar eruptions, with energies reaching up to 10²⁰ eV, and their abundance generally increases as energy decreases. Prolonged exposure to this type of radiation can lead to damage to biological tissues, posing a significant factor in evaluating health risks for astronauts. At the Institute of Medical Physics and Biophysics, research is being conducted to study the effects of low-energy protons on biological samples. Irradiation experiments on cell cultures allow for the analysis of cellular damage mechanisms and the evaluation of DNA repair capacity. Damage to cellular structures caused by ionizing radiation is a critical aspect not only in space research but also in medicine, particularly in relation to radiation therapy for cancer treatment. Studying these processes provides valuable insights into the biological consequences of proton radiation exposure, contributing to the development of protective measures for astronauts as well as the optimization of therapeutic approaches in oncology. This study focuses on conducting a series of irradiation experiments on cell cultures to evaluate the impact of physical parameters such as proton beam energy, exposure time, and source distance on the morphological and structural changes in cells. These experiments will enhance the understanding of ionizing radiation interactions with biological systems and contribute to expanding knowledge in the fields of radiobiology and space medicine.

We also deal with the use of other physical methods in the study of cells and tissues, mainly in terms of the presence of metals (iron, copper, ...) and other substances foreign to the body that accumulate in them for certain reasons (metabolic disorders, environmental pollution, ...). Recently, this has mainly been the study of the localization, distribution, structure and magnetic properties of iron in selected brain structures through various histological, immunohistochemical methods and mainly physical methods. We also use light (polarizing, fluorescence) and electron (scanning and transmission) microscopes with EDX analysis. Most recently, we use SQUID magnetometry and Mössbauer spectroscopy in the investigation of iron oxides.

Using transmission electron microscopy (TEM), we are able to observe ultrastructural changes in tissues and cells at the nanometer level.  

Scanning electron microscopy (SEM) with energy-dispersive analysis (EDX) makes it possible to investigate the structure and elemental composition of particles in cells and tissues.

The most abundant heavy metal, iron, is stored in human body mainly in the brain tissue. Iron is a fundamental cofactor of many different enzymes in the human body and it is needed therefore for normal neuronal function. It is well known that metal ions in substantia nigra (SN) are associated with neuromelanin structure in substantia nigra pars compacta. Neurons store iron in the form of ferrous ions which is linked with neurodegenerative diseases such as Alzheimer’s and Parkinson’s, Friedreich’s ataxia, and Huntington’s disease. Post-mortem brain tissue sections from SN were obtained during the autopsy to prepare tissue sections for the pathology diagnosis at the Institute of Pathological Anatomy of the Comenius University. Original samples of substantia nigra pars compacta were first investigated by light microscopy and SEM (scanning electron microscopy) with EDX (Energy-Dispersive X-ray spectroscopy) for qualitative analyses. Thin slices (5mm) of the brain sections were placed on 2 μm Mylar foil and then fixed on frame holders. X-ray spectra from the PIXE analysis using 3 MeV proton beam (1 – 2 mm spot in diameter) with the intensity of ~ 3 nA with the sample tissue were collected. Up to 30 spots were measured on each sample. Fe, Mn, Cr and Zn concentration distribution maps were created. Maps with highest observed values for individual elements are shown in the figure (gray color represents the background level of the measurement).

Published in Journal of Radioanalytical and Nuclear Chemistry

Pánik, J., Kopáni, M., Zeman, J., Ješkovský, M., Kaizer, J., Povinec, P. P., (2018), Determination of metal elements concentrations in human brain tissues using PIXE and EDX methods, Journal of Radioanalytical and Nuclear Chemistry, 318, 2313–2319, doi: 10.1007/s10967-018-6208-3.

In cooperation with Medical faculties of the Comenius University in Bratislava and Martin a rabbit brain slice samples were received to determine iron concentrations and map its distribution in the specimen. The aim of this study was to evaluate concentrations of iron in these samples on various spots. It is expected that the iron in the rabbit brain was produced by electromagnetic radiation similar to one generated in mobile telephones. The observed effects in the brain tissue may be due to electromagnetic radiation, which causes agglomeration of iron in the tissue.

Proton beam (3 MeV energy, 300 pA intensity and 1.5 mm diameter) was used for the analysis of 4 samples:

• Blank sample unexposed to electromagnetic (EM) radiation
• Sample denoted as “First sample”, exposed to EM radiation. High Fe concentration (up to 50 ppm)
• 2 samples, RB01 and RB02 exposed to EM radiation. Low Fe concentration (up to 5.5 ppm) 

A photograph of each sample was placed into the background of the Fe concentration maps. Dimensions of samples in millimeters are shown in the graphs. Fe concentration scale is different for the “First sample” because of much higher values compared to the other 3 samples.

Published in Bratislava Medical Journal