Unusual enhancement of the radical production in the X-ray irradiated aqueous-organic systems containing W(VI) in homogeneous and nanoparticle forms

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 modific...

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Bibliographic Details
Published in:	Radiation physics and chemistry (Oxford, England : 1993) Vol. 222; p. 111812
Main Authors:	Shiryaeva, Ekaterina S., Vanina, Anzhelika I., Baranova, Irina A., Sanochkina, Elizaveta V., Kameneva, Svetlana V., Taran, Glafira S., Belousov, Alexandr V., Klechkovskaya, Vera V., Feldman, Vladimir I.
Format:	Journal Article
Language:	English
Published:	Elsevier Ltd 01-09-2024
Subjects:	EPR spectroscopy Nanoparticles Radicals Spin trapping Tungsten X-rays irradiation Nanoparticles X-rays irradiation Spin trapping Tungsten Radicals EPR spectroscopy
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Summary:	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. •Effect of X-ray irradiation on model aqueous organic systems was studied by spin trapping/EPR.•Increase of radical yield was found in the presence of Na2WO4 and WO3 nanoparticles.•The size effect on radical yield was observed for WO3 nanoparticles.•The effect was explained by combination of “physical” and “chemical” enhancement.•The radiation-chemical mechanism of the effect and its implications are discussed.
ISSN:	0969-806X 1879-0895
DOI:	10.1016/j.radphyschem.2024.111812