The expanding biomedical applications of hybrid nanomaterials demand synthesis methods ensuring high purity and precise control over particle size and distribution. Here, we report the synthesis of raspberry-like Ta2O5-Au hybrid core-shell nanoparticles via in situ electron-beam radiolytic reduction of Au3+ions in the presence of polydopamine (PDA)-coated Ta2O5 cores. Synthesis was performed without the addition of chemical reducing agents, operated at room temperature, and allowed precise control over synthesis parameters, providing a sustainable and scalable route for hybrid nanoparticle production. We investigated the effects of oxide surface chemistry, radiation dose and dose rate, and HAuCl4 concentration on Au nanoparticles binding efficiency and particle size. UV-vis and TEM analyses revealed that reduction of Au+3 in the presence of Ta2O5@PDA cores yielded raspberry-like Ta2O5-Au hybrids with small and uniformly distributed Au nanoparticles, compared to rather large Au nanoparticles formed in core-free solutions. Surface chemistry critically influenced hybrid formation: unmodified Ta2O5 cores did not yield hybrids under alkaline conditions, whereas PDA-coated Ta2O5 cores successfully facilitated Au nanoparticle attachment. Increasing electron-beam dose enhanced surface-bound Au fraction from ti 32 % at 5 kGy to ti 82 % at 120 kGy, while increasing dose rate from 2.5 kGy/ min to 80 kGy/min at 40 kGy reduced the anchoring of Au nanoparticles from ti 78 % to ti 58 %. Post-irradiation pH changing to the Ta2O5@PDA isoelectric point enables complete Au nanoparticle binding by minimizing electrostatic repulsion. Au nanoparticle size was tunable from approximately 5-13 nm by varying dose and precursor concentration. The synthesized hybrids demonstrated higher computed tomography (CT) contrast than iohexol and Ta2O5, highlighting their promising potential as next-generation CT contrast agents.

Hybrid Ta2O5/Au nanoparticles (NPs) were synthesized by in situ radiolytic reduction of Au ions in a tantalum oxide hydrosol. For efficient Au binding, Ta2O5 NPs were preliminarily modified with a polydopamine (PDA) layer. This one-pot approach allows the monodispersed Au NPs to be directly anchored on the Ta2O5@PDA surface, which compares favourably with the conventional multi-stage method for synthesizing such structures.

New compounds consisting of 2,6-di-tert-butylphenol and isomeric pyridinecarboxamide moieties as well as their water-soluble hydrochlorides were synthesized. The compounds appeared to be potent antioxidants and radioprotectors, with no significant difference in activity between the pyridine bases and their salts. The cytotoxicity assay showed no significant toxic impact from any of the substances, making them promising candidates for further investigation. Antioxidant and radioprotective moiety Pyridinecarboxylic acid amide fragment

This paper reports synthesis and characterization of three new coumarin-fused NIR BODIPY dyes 16-18, - 18 , as well as the detailed study of their optical response to exposure with X-rays (up to 1000 Gy) in solvents of various nature. A strong reaction to irradiation (both in terms of absorption and fluorescence changing) is found in chlorinated solvents (CCl4 4 and CHCl3) 3 ) and acetonitrile, while no significant respond of the dyes is observed in toluene and propanol-1. Herewith, their responses turned out to be very versatile: a complex change in fluorescence (quenching of the main band accompanied by the flare-up in a new spectral region) is observed together with colorimetric reaction (e.g., the color of 17 changes from green to blue at 50-80 Gy, and then becomes pink closer to approximate to 350 Gy). In general, the dyes show good linearity in their response to irradiation up to approximate to 70-100 Gy and are quite sensitive. For example, the limit of detection (LOD) values for 18 are from 0.29 to 6.73. At the same time, the ratiometric fluorescent response of the compound 16 turns out to be linear over the entire range up to 1000 Gy (to date, this is the first BODIPY-based X-ray probe with optical response over such a wide dose range). Thus, the synthesized dyes seem to be promising for dosimetric support of radiation processing/sterilization procedures.

The metal and oxide nanoparticles (NPs) containing various elements with high atomic number (Z) are considered as prospective sensitizers for the production of radicals upon X-ray irradiation of aqueous solutions, which can be used for different applications in medical treatment and material modification. The common basis for the sensitizing effect in oxygen-free systems is concerned with increase of the absorbed dose due to the presence of high-Z atoms (known as physical enhancement, relatively insensitive to the NP size). In this work we report the first experimental evidence for extra enhancement of the radical yield in a model oxygen-free aqueous organic system irradiated with X-rays (45 kVp) in the presence of W(VI) compounds, both in homogeneous solutions of Na2WO4 and in the form of ultra-small NPs of WO3. Meanwhile, in the case of larger WO3 NPs the radical yield is consistent with physical enhancement mechanism. In the case of systems containing HfO2 NPs only physical enhancement was observed, independent of the NP size. Unusually large enhancement of radical production and size effect for W(VI) in homogeneous and NP forms was tentatively attributed to the radiation-chemical processes involving intermediate formation of metastable W(V) due to reactions of hydrated electron.

A fundamental possibility of using the ability of low-molecular-weight DNA molecules to form optically active cholesteric liquid-crystalline dispersions (CLCDs) to estimate the efficacy of DNA-binding radioprotectors is studied. On the example of the well-known dye Hoechst 33 258, which interacts with DNA by the minor-groove-binding and has pronounced radioprotective properties, it is shown that the change in the amplitude of anomalous signal of circular dichroism of the CLCDs formed from DNA molecules preliminarily irradiated with X-rays in the absence and in the presence of the test compound makes it possible to estimate the value of its protective effect.

This paper reports the results of a detailed study of the optical response of boron difluoride curcuminoids to radiation exposure. Two lines of the dyes fundamentally different in structure (namely, symmetrical and asymmetrical) were tested. If the absorption responses of their solutions in chloroform to X-rays turns out to be quite close quantitatively (note that it has a very indicative visual manifestation – a gradual discoloration is observed in the dose range up to 300 Gy), the fluorescence ones differ notably: among other things, the former demonstrate much more sensitive reactions (the corresponding limit of detection values ​​differ by up to 2.36-fold). Nevertheless, in both parameters, these dyes generally show good linearity of the response as in classical coordinates (up to ≈ 100–150 Gy), as in semi-logarithmic ones (up to 1000 Gy). Since the main reason for such behavior seems to be the radiation-induced decomposition of the dyes, its possible scheme and corresponding “weak links” in the structure of the molecules (in other words, radiosensitive elements) are proposed for each case. For example, these include N(CH3)2 fragments at the ends of dimethylaminostyryl groups. It is precisely their detachment that determines the observed optical response of asymmetrical dyes. Thus, the results obtained provide some insight into the possibilities of controlling the sensitivity of organic dyes to irradiation by changing their structure.

The most important problem of atomic energy is the reprocessing of spent nuclear fuel and management of high-level radioactive waste (HLW). The separation of americium(III) from HLW remains a severe problem, the solution of which is necessary for the sustainable development of nuclear energetics. Two novel phenantrolinediamide ligands having methyl groups in the ortho-positions of the aryl fragments demonstrate record values for the separation factors of Am(III) and light lanthanides(III) including HLW imitator solution containing 10.7 g/L of lanthanides(III), 0.5 g/L of Pd, and 0.2 g/L of Zr in 3 mol/L nitric acid solution. They also have a high extraction equilibrium rate, high radiolytic stability, and fully reversible extraction, which allows americium back-extraction to be performed using dilute nitric acid. The mechanism of complexation using SC-XRD and DFT calculations was investigated to demonstrate the importance of formation complexes having a ligand:metal 2:1 ratio.

Исследована принципиальная возможность использования способности молекул ДНК низкой молекулярной массы образовывать оптически активные холестерические жидкокристаллические дисперсии (ХЖКД) для оценки эффективности ДНК-специфичных радиопротекторов. На примере широко известного красителя Hoechst 33258, взаимодействующего с ДНК по модели связывания в малой бороздке и обладающего выраженными радиозащитными свойствами, показано, что изменение амплитуды аномального сигнала кругового дихроизма ХЖКД, формируемых из молекул ДНК, предварительно облученных рентгеновским излучением в отсутствии и в присутствии исследуемого соединения, позволяет оценить величину его защитного действия.

Bisbenzimidazoles have a broad spectrum of potential applications: radioprotectors, drug delivery vectors, antiviral agents, etc. At the same time, they seem to be promising fluorescent probes for radiation measurements. Therefore, in the present work, a fluorescent response to X-ray irradiation of Hoechst 33258, one of the most widely known representatives of the bisbenzimidazole family, was studied for the first time. Irradiation of the dye was performed in aqueous and organic solutions (DMSO and glycerol), as well as in their mixtures. It is shown that the reaction of the dye to radiation exposure is very versatile and may be controlled by the solvent properties, which makes it possible to build relationships between the absorbed dose and a wide variety of parameters of its fluorescence signal. For example, irradiation may induce fluorescence quenching caused by the degradation of the dye, a change in the position of the fluorescence band maximum due to the modification of the dye molecules or to the radiation-induced changes in the properties of the medium, as well as a fluorescence flare-up mediated by the changes in pH.

High-energy accelerators are often used in oncological practice, but the information on the small-field dosimetry for the photon beams with nominal energy above 10 MV is limited. The goal of the present work was to determine the values of the output correction factor ( kQclin,Qreffclin,fref$k_{{Q}_{{\rm{clin}}},{Q}_{{\rm{ref}}}}^{{f}_{{\rm{clin}}},{f}_{{\rm{ref}}}}$ ) for solid-state detectors (Diode E, PTW 60017; microDiamond, PTW 60019), EBT3 film, and ionization chambers (Semiflex, PTW 31010; Semiflex 3D, PTW 31021; PinPoint, PTW 31015; PinPoint 3D, PTW 31016) in the small fields formed by 10, 15, 18, and 20 MV photon beams. The output correction factors were calculated by Monte-Carlo method using EGSnrc toolkit for six field sizes (from 0.5×0.5cm2$0.5 \times 0.5\ {\rm{cm}}^2$ to 10×10cm2$10 \times 10\ {\rm{cm}}^2$ ) for isocentric and constant source-to-surface distance (SSD) techniques. The decrease in the field size led to an increase in kQclin,Qreffclin,fref$k_{{Q}_{{\rm{clin}}},{Q}_{{\rm{ref}}}}^{{f}_{{\rm{clin}}},{f}_{{\rm{ref}}}}$ for ionization chambers, while for solid-state detectors and radiochromic film, kQclin,Qreffclin,fref$k_{{Q}_{{\rm{clin}}},{Q}_{{\rm{ref}}}}^{{f}_{{\rm{clin}}},{f}_{{\rm{ref}}}}$ were less than unity at the smallest field size. A larger sensitive volume of ionization chamber corresponded to a stronger deviation of output correction factor from unity: 1.847 (125 mm3 PTW 31010) versus up to 1.183 (16 mm3 PTW 31016) at the smallest field of 10 MV beam. The calculated output correction factors were used to correct the output factors for PTW 60017, PTW 60019, and EBT3. The deviation of the corrected output factor from the results of Monte-Carlo simulation did not exceed 3% in the fields from 1.0×1.0cm2$1.0 \times 1.0\ {\rm{cm}}^2$ to 4.0×4.0cm2$4.0 \times 4.0\ {\rm{cm}}^2$ for 10 and 18 MV beams. Thus, Diode E, microDiamond, and EBT3 film can be recommended for small-field dosimetry of high-energy photons.

The paper analyzes the features of the spatial and energy distributions of photons in depth, in radius and in energy for small fields created in water by narrow beams of high-energy bremsstrahlung radiation from medical accelerators and mono-directional, monoenergetic beams of photons. In particular, the relationship between the spatial dependences of the absorbed dose, total kerma, and ionization kerma is discussed. Using numerical simulation, the features of photon spectra in small fields at a depth of 10 cm in a water phantom for bremsstrahlung beams with maximum energies of 10, 15, 18 and 20 MeV were determined as applied to the design of Varian accelerator heads. It is shown that, in contrast to wide fields, the energy distribution of photons in these fields practically does not change within the central region of the field and strongly softens when leaving this region. With a decrease in the size of small fields from 4.04.0 to 0.50.5 cm, a certain hardening of the spectra is observed in the central region (the average energy increases by 2–4 %) and is much more significant outside this region. The work also determined the values of the clinical dimensions of small fields generated by high-energy beams of Varian accelerators of different energies in a water phantom at a depth of 10 cm, depending on the settings of the collimation system. This work was carried out with the financial support of the Russian Foundation for Basic Research and SITMA within the framework of scientific project No. 18-52-34008.

Liquid crystals (LCs) can be promising for detection of ionising radiation (IR). However, there is little information about their interaction with IR and there are no systemic studies of the dosimetric application of LCs. In this communication, we show for the first time the capabilities of a new type of radiation detector - cholesteric liquid-crystalline dispersion (CLCD) of DNA obtained using polyethylene glycol (PEG) and salt indued condensation. Irradiation of the DNA CLCD samples with 0-100 kGy of 7.6 MeV bremsstrahlung led to significant change in their circular dichroism (CD): approximate to 5% and approximate to 12% increase in the signal was observed at 10 and 20 kGy, while in the range of 20-90 kGy the CD signal decreased linearly. Thus, detectors based on DNA CLCD could be of interest for such application of IR as material modification or radiation sterilisation. At the same time irradiation can help to stabilise dispersion particles and can be used to prevent their sedimentation. Unirradiated samples degraded within 24 h after preparation, while the irradiated ones were able to maintain the intensity of CD signal for more than 168 h.Schematic representation of the dual effect of radiation exposure the DNA CLCD.

Using cholesteric liquid-crystalline dispersion (CLCD) of DNA, we demonstrate that the molecularly organized systems may be used both for qualitative assessment of the degree of radiation-induced DNA damage, as well as for detection of radiation doses in a very wide range. The doses up to 500 Gy do not cause any significant changes in optical signals of DNA in solution. However, when irradiated molecules are used to prepare the CLCD by addition of crowding polymer, a clear correlation of its optical signals with an absorbed dose is observed. For example, at a dose of 500 Gy, a maximum drop in the circular dichroism (CD) signal for DNA solution and for CLCD formed from preliminary irradiated molecules is ≈20% and ≈700%, respectively. This approach can also be used to expand the dosimetric capabilities of DNA CLCD. Compared to the case of irradiation of ready-made DNA CLCD, formation of the dispersed system from irradiated DNA allows to increase its sensitivity by more than 2 orders of magnitude. A similar decrease in the CD signal (≈1.45-fold) is observed in these systems at the doses of 100 kGy and 200 Gy, respectively. This principal approach seems to be relevant for other biomolecules and molecularly organized systems.

Gold nanoparticles (GNPs) are promising radiosensitizers for cancer radiotherapy. Moreover, they can be used in the same way for radiation processing and sterilization. Such application of GNPs is of practical interest since it may significantly reduce the dose load and expand the application of radiation treatment. In the present study, the high radiosensitization effect of GNPs in relation to viral particles is demonstrated for the first time. The preparations of tobacco mosaic virus (TMV) are used as an experimental model, insofar as this virus has the same properties as animal and human ones but is safe for humans. Irradiation with 45 kVp X‐ray to the doses of 4 and 7 kGy leads to a decrease in the infectious activity of TMV virions up to 1.92‐ and 2.70‐fold, respectively. At the same time, irradiation in the presence of 0.4 mg mL −1 of 12 nm spherical GNPs increases the efficiency of virus inactivation up to 15‐ and 22‐fold. The GNPs enhance both the damage to capsid protein due to the enhanced generation of reactive oxygen species and genome RNA due to the emission of secondary radiation. These results show the great prospects of the application of high‐ Z nanoparticles in radiation treatment.

In this study we have probed the role of different enhancement mechanisms of the nanosensitizers in the X-ray irradiated oxygen-free model aqueous organic systems containing "bare " gold nanoparticles (AuNPs) using the spin-trapping technique with electron paramagnetic resonance detection. The observed enhancement effect was found to be ca. 1.67 wp(-1) for the AuNPs with an average diameter of 18 nm and 45 kVp X-rays. The comparison with Monte Carlo simulation shows that the sensitizing effect of AuNPs in the X-ray irradiated oxygen-free aqueous organic systems could be attributed to the increasing absorbed dose due to high absorption cross-section of gold atoms. It implies that the radiation-chemical yield of hydroxyl radicals responsible for the oxidative damage in the absence of oxygen remains virtually unchanged in the presence of AuNPs. Also, no clear evidence was found for the dose rate effects upon variation of this parameter by more than an order of magnitude (0.06-1.21 Gy/s). In practical sense, these results urge the development of new efficient approaches for the radiation treatment of hypoxic media using nanoparticles.& nbsp;& nbsp;

In the present work Fo center dot rster resonance energy transfer (FRET) between DNA-specific fluorescent dyes Hoechst 33258 (Ht58; donor) and SYBR Green I (SG; acceptor) is compared in isotropic DNA solution and in its chole-steric liquid-crystalline dispersion (DNA CLCD). At a fixed donor concentration of 3.57 x 10-6 \M in the spatially ordered system, FRET starts at lower acceptor concentration than in the isotropic system and at the SG con-centration below 1.05 x 10-7 M, its efficiency in DNA CLCD is up to X4-fold higher than in DNA solution (3D -FRET vs. 1D-FRET). However, the maximum FRET efficiency is higher in isotropic solution (X70% vs. X50%, respectively) apparently due to the absence of steric restrictions on intermolecular interactions imposed by the dense packaging of the DNA molecules. In isotropic DNA solution FRET from Ht58 to SG is accompanied by the displacement of Ht58 from the minor-groove complex as the SG concentration increased, while the displacement of Ht58 in DNA CLCD seems to be limited. Using FRET between Ht58 and SG, the formation of DNA CLCD particles via stopped-flow method was investigated and for the first time the subsecond stage of the DNA CLCD particle formation, generation of "precholesteric" optically inactive nuclei, was demonstrated.

Nanoparticles (NPs) with a high atomic number (Z) are promising radiosensitizers for cancer therapy. However, the dependence of their efficacy on irradiation conditions is still unclear. In the present work, 11 different metal and metal oxide NPs (from Cu (ZCu = 29) to Bi2O3 (ZBi = 83)) were studied in terms of their ability to enhance the absorbed dose in combination with 237 X-ray spectra generated at a 30–300 kVp voltage using various filtration systems and anode materials. Among the studied high-Z NP materials, gold was the absolute leader by a dose enhancement factor (DEF; up to 2.51), while HfO2 and Ta2O5 were the most versatile because of the largest high-DEF region in coordinates U (voltage) and Eeff (effective energy). Several impacts of the X-ray spectral composition have been noted, as follows: (1) there are radiation sources that correspond to extremely low DEFs for all of the studied NPs, (2) NPs with a lower Z in some cases can equal or overcome by the DEF value the high-Z NPs, and (3) the change in the X-ray spectrum caused by a beam passing through the matter can significantly affect the DEF. All of these findings indicate the important role of carefully planning radiation exposure in the presence of high-Z NPs.

In recent years, members of the Coronaviridae family have caused outbreaks of respiratory diseases (MERS, SARS, and COVID-19). At the same time, the potential of radiation-induced inactivation of this group of viruses have been little studied, although radiation technologies can be widely used both in the processing of personal protective equipment and in the sterilization of vaccines. In the present work, the effect of 10 MeV electron beams and 7.6 MeV bremsstrahlung on the coronavirus infection pathogen (transmissible gastroenteritis virus) has been studied in vitro. In the given experimental conditions, irradiation with photons turned out to be more effective. The virus-containing suspension frozen at –86°C was the most resistant to radiation: the dose required for complete inactivation of the virus in this case was from 15 kGy, while for the liquid suspension and lyophilized form the sterilizing dose was from 10 kGy. At lower radiation doses for all samples during passaging in cell culture, residual infectious activity of the virus was observed. These differences in the efficiency of inactivation of liquid and frozen virus-containing samples indicate a significant contribution of the direct effect of radiation.