Original title of the article: Palladium-103 as a theranostic Auger electron emitter: from cyclotron production to preclinical SPECT evaluation in murine and canine models

In oncology, targeted radionuclide therapy is one of the most promising treatment methods, as it localises cytotoxic radiation within tumour tissues with a high degree of specificity. Although the beta (β) and alpha (α) emitters used to date have demonstrated high efficacy, their tissue penetration ranges from micrometres to millimetres, which may cause collateral damage to surrounding healthy tissue as well. A new and alternative approach is the use of Auger-electron-emitting radioisotopes, whose tissue penetration is on the order of nanometres; they cause virtually no radiation damage to surrounding tissues, but only to those tumour cells where they have accumulated as a result of targeted accumulation. The energy released by β-emitting radionuclides is typically only sufficient to induce single-strand DNA breaks, whilst both α-particles and Auger electrons are capable of causing double-strand breaks. Cells are generally able to recognise and repair single-strand breaks, but double-strand breaks represent a critical form of damage that often leads to cell death (apoptosis) or the irreversible loss of viability. Just as with DNA damage to the cell nucleus, high-dose irradiation of the mitochondria within the cell is also lethal to the cell, and this effect can only be achieved with radiation having a sufficiently high linear energy transfer (LET) (very high energy transfer to the surrounding tissue over a very short distance). Az alfa-részecskék mutatják a legmagasabb LET-et (50–230 keV/µm), míg az Auger-elektronok egy köztes LET-tartományba esnek (4–26 keV/µm), ami jelentősen magasabb, mint a béta-részecskéké (≈0,2 keV/µm). Although they do not achieve the LET values of α-emitters, an important advantage of Auger electron emitters over α-emitting radionuclides in tumour therapy is their extremely short absorption range, as mentioned earlier, which makes them uniquely capable of inducing double-strand DNA breaks whilst sparing neighbouring healthy tissue.

In this article, we present our research into radiopharmaceuticals using the palladium-103 Auger electron emitter radioisotope. We begin with isotope production in the cyclotron, followed by isotope separation and purification, which is a revolutionary new technique based on the varying rates of evaporation of metals at extremely high temperatures. We incorporate the purified radioisotope into a molecule that is capable of selectively reaching cancer cells and accumulating there. These molecules are known as vector molecules. We have also tested these radioactively labelled molecules in animal experiments. This typically involves two phases: the first is the so-called small-animal model, for which we used mice. The second step involved experiments with ‘large-bodied’ animals, which are closer in size to humans; in our case, this was a Hungarian Vizsla. The results not only demonstrated selective accumulation, but also showed a temporary improvement in the dog with liver cancer, despite the relatively low dose of the substance. On the basis of our further findings published over the last two years, we have become a key member of the international organisation established to promote Auger electron therapy in Europe.

Original title of the article: Low-lying excited states in 46S and 47S

Most stable atomic nuclei – particularly those with an even number of protons and an even number of neutrons – are nearly spherical in their ground state; however, a significant proportion of atomic nuclei have a different, deformed shape. This deformed shape may be elongated cigar-shaped, flattened disc-shaped, or even a triaxially deformed ellipsoid resembling a kiwi. These shapes depend on the shell structure of the protons and neutrons, as well as on the collective interactions occurring within the nucleus.

The shape of an atomic nucleus is not always a fixed property. The same atomic nucleus can assume different shapes at excitation energies that are close to one another. This phenomenon is known as shape coexistence. In such cases, structures associated with spherical and deformed shapes, or even shapes deformed in different ways, may compete with each other. Tracking the evolution of nuclear shape can provide important information about the shell structure and collective motions of atomic nuclei.

In the chain of sulphur isotopes with proton number Z = 16, the shell structure changes significantly as the neutron number increases, leading to a weakening of the spherical shape and the emergence of deformed configurations. As we move through the sulphur isotopes with even numbers of neutrons, we encounter systems of various shapes, and near the neutron drip line, shape coexistence and enhanced collectivity may also develop.

Since the early 2000s, researchers at the HUN-REN Institute for Nuclear Research have been investigating the structure of neutron-rich atomic nuclei lying below the calcium isotopes in experiment using radioactive ion beams in leading European (GANIL, France) and Japanese (RIKEN) institutes in the framework of international collaborations. By analysing data collected during the latest gamma-spectroscopic measurements carried out at the RIKEN Radioactive Isotope
Beam Factory, several new gamma transitions have been assigned, and a number of excited states have been identified in sulphur nuclei with mass numbers 46 and 47, located near the neutron drip line. Based on the energies and quantum mechanical properties of the states, it was concluded that, in addition to the ground-state elongated cigar shape, a triaxial deformation is present in the nucleus S-46; this has been confirmed by modern theoretical calculations. 

Original title of the article: Elastic α-scattering experiments on 88Sr to constrain the α-induced reaction cross-sections for weak-r-process studies

One of the aims of nuclear astrophysics is to investigate the formation of various chemical elements. The formation of isotopes with lower mass numbers is linked to the life and evolution of stars, whilst the formation of heavier elements (those beyond iron) is primarily associated with the final stages of a star’s life and its death. The study of these processes is important for understanding how the Universe works and for explaining the formation of our known universe. Since the behaviour of stars is fundamentally governed by the nuclear reactions taking place within them, understanding these reactions is also of fundamental importance. Using flexible α-particle scattering experiments, the relevant nuclear reactions can be described with a high degree of accuracy, and the results of measurements of the α-induced reaction cross-sections can also be verified.

In this work, we investigated a reaction that is important from the point of view of nuclear evolution, for which current measurements show a significant deviation from the generally well-established theoretical predictions. In our experiment, by studying the elastic scattering of alpha particles on 88Sr nuclei, we indirectly determined the cross-section of the 88Sr(α,n)91Zr reaction, which we compared with direct measurement results found in the literature.Our results are in excellent agreement with theoretical predictions, and we have not been able to reproduce the discrepancy observed in previous measurements.

The original title of the article: Effective mercury removal from water using aromatic isocyanides as reducing agents

Removing mercury from water is one of the most critical environmental challenges of our time. As part of our research group’s latest findings, we have developed an innovative chemical process that can extract this heavy metal from aqueous media in a manner that is far more sustainable than current industrial standards and without producing toxic byproducts.

Mercury enters the environment primarily through industrial and agricultural activities. One of the most serious problems in environmental chemistry is that inorganic mercury entering natural waters is converted by aquatic microorganisms into a much more dangerous organic compound, methylmercury. This form is easily incorporated into the vital tissues of living organisms and moves up the food chain. As it moves from microscopic aquatic organisms to fish, and from fish to top predators—including humans—its concentration continues to multiply, posing a serious health and environmental risk.

Due to the toxicity of mercury, extremely strict legal limits apply to its concentration in water. In accordance with EU regulations, under Hungarian Government Decree No. 5/2023 (January 12), the maximum permissible concentration of mercury in our drinking water is only 1 microgram per liter (1 µg/L). This limit is ten times stricter than the more widely known Hungarian limit for arsenic.

The regulations governing our rivers and lakes are even stricter than that. The problem is further exacerbated by drought conditions associated with climate change: as water supplies dwindle, pollutant concentrations may increase locally, thereby intensifying the toxic effects on ecosystems.

Munkánk megkezdésekor abból a problémából indultunk ki, hogy a jelenleg leginkább elterjedt ipari eljárások, pl. adszorpció, kicsapás és az ón(II)-kloriddal történő higanykivonás bár működőképesek, komoly környezetvédelmi kompromisszumot követelnek. A folyamat során ugyanis nagy mennyiségű, toxikus másodlagos hulladék: szennyezett szén vagy óniszap képződik, amelynek biztonságos elhelyezése újabb terhet ró a környezetre.

Kutatásunk során sikerült azonosítanunk egy új vegyületcsaládot, amely kiválóan alkalmazható az ipari technológiákban használt vizek higanymentesítésére. A vizsgált molekulák közül az ICAN (1-amino-5-izocianonaftalin) nevű vegyület bizonyult a legkiemelkedőbbnek. Az ICAN teljesen szelektív és sztöchiometrikus kémiai reakcióba lép a higanyvegyületekkel, elemi higany és aminvegyületek képződése közben. Munkánk során kidolgoztunk egy olyan eljárást, amellyel közel teljes mértékben el tudjuk távolítani a higanyt a vízből, gázzal, pl. levegővel való kihajtással. Kísérleteink igazolták, hogy a módszerünk már egészen kis anyagmennyiség felhasználásával is eléri a jelenleg használt ón-klorid hatékonyságát – megbízhatóan 1 µg/L alatti maradék higanyszintet produkálva – azonban a mérgező óniszap képződése nélkül.

Az általunk fejlesztett eljárás egyik legfontosabb analitikai eredménye, hogy nemcsak ipari körülmények között, hanem a komplex, nagy sótartalmú tengervízben is rendkívül hatékonynak bizonyult. Ez a robusztusság azt mutatja, hogy az új technológia a jövőben nemcsak a hazai ivóvíz- és iparivíz-kezelésben hozhat áttörést, hanem globális szinten is eszközt adhat a szakemberek kezébe a szennyezett tengeri élőhelyek kármentesítésére.

The original title of the article: Comparative micro-XRF study of objects from the Hungarian conquest period of Hajdú-Bihar County, Hungary

The Age of the Hungarian Conquest understandably holds a special place in Hungarian history, but its significance is perhaps even greater when viewed in the context of European history. In recent years, scientific analysis of metal artifacts from the Age of the Hungarian Conquest found in Hungary and across Europe has begun, resulting in the publication of elemental analysis results for nearly 300 artifacts in various, primarily Hungarian-language publications. Our goal was to introduce this area to an international audience as well. While previous research was always limited to the artifacts from a single grave, cemetery, or archaeological site, we set out to use our investigations to provide a representative picture of the entire Hajdú-Bihar County. Accordingly, we selected artifacts from various types of objects, as well as from all types of cemeteries dating to the Hungarian Conquest period, for analysis. Microscopic examinations were performed using a Keyence VHX-6000 digital 3D microscope, and elemental composition was determined using a Bruker M4 TORNADO micro-XRF analyzer. Until now, objects have been classified primarily on the basis of their external characteristics or manufacturing techniques; however, we have attempted to base our comparison on scientific principles and have grouped them according to their elemental composition. Although the artifacts exhibited a high degree of heterogeneity within a single site, and it was not possible to clearly distinguish between finds from different periods of the Hungarian conquest based on their composition, there was a correlation between the artifacts’ function and their elemental composition.

We have supplemented the 300 artifacts examined so far in this project with data on 47 additional objects, thereby laying the foundation for a potential database. In the future, we plan to continuously expand the database and conduct a more comprehensive statistical analysis.

The original title of the article: An interstellar energetic and non-aqueous pathway to peptide formation

Outer space is a cold, rarefied, and inhospitable environment exposed to particle and photon radiation. Nevertheless, with the advancement of molecular astronomical methods, a multitude of complex chemical compounds have already been identified there. Simple molecules that freeze out in cold interstellar clouds, comets, interplanetary dust, or ice particles are not only broken down by cosmic radiation but can even be transformed into more complex molecules. Space chemistry investigates whether molecules essential for life can form in the unique environment of outer space, and if so, how—a question that touches on one of the most fundamental aspects of human curiosity.

During experimental work conducted at the AQUILA (ATOMKI-Queens University Ice Chamber for Laboratory Astrochemistry) and ICA (Ice Chamber for Astrophysics)/ Astrochemistry) facilities, we bombarded glycine samples—labeled with various isotopes and similar to interstellar ice—with proton beams at energies of 10 keV and 1 MeV. Glycine is the simplest protein-forming amino acid and has previously been detected in meteorites and comets. The purpose of the proton irradiation was to model the effects of cosmic rays and the solar wind under conditions typical of the environments found in interstellar clouds or young planetary systems. The samples were irradiated in an ultra-high vacuum at a temperature of 20 K.

During irradiation, we continuously monitored the chemical changes in the material using Fourier-transform infrared spectroscopy (FTIR) and detected, among other things, the formation of CO₂, CO, OCN⁻, as well as H₂O and D₂O molecules. The amide bands appearing in the infrared spectra indicated that peptide bonds were forming between glycine molecules. Peptides are the building blocks of proteins and are therefore directly linked to the chemical structure of living systems. High-resolution mass spectrometry analysis (ex situ) performed after irradiation ultimately confirmed the formation of the simplest dipeptide, glycyl-glycine.

This discovery significantly broadens our understanding of the origin of life. It shows not only that the fundamental molecules necessary for life can form even in outer space, in a purely radiative environment, but also—contrary to previous assumptions—that these processes do not necessarily require liquid water or an Earth-like environment.

The work was carried out within the framework of a broad international collaboration involving, in addition to the Institute for Nuclear Research, research groups from Aarhus University, Queen Mary University of London, Queen’s University Belfast, and the University of Kent. The results of the research were published in the journal *Nature Astronomy*, which underscores the international significance of the topic.