We report on strong X-ray-induced hydroxyl radical (^. $\mathrm{O}\mathrm{H}$ ) generation in an aqueous solution containing UV light pre-treated GdYVO₄:Eu³⁺ nanoparticles (L-GdYVO). The methods of optical spectroscopy were used to detect ^. $\mathrm{O}\mathrm{H}$ in the solutions. The complex nature of the mechanism of ^. $\mathrm{O}\mathrm{H}$ generation has been revealed and discussed. The experimental data obtained indicate that the mechanism of ^. $\mathrm{O}\mathrm{H}$ generation is associated with two main processes: (i) direct ^. $\mathrm{O}\mathrm{H}$ generation with the participation of thermalized h⁺ formed at X-ray irradiation, and (ii) X-ray-facilitated jumps of h⁺ formed in the nanoparticles’ (NPs’) valence band at UV light pre-treatment and trapped in local levels formed by random scattering potential. At the same time, for GdYVO₄:Eu³⁺ nanoparticles, which were not exposed to UV light before the X-ray irradiation (D-GdYVO), a strong radioprotective effect ascribed to the electron-donation properties of V⁴⁺ ions was observed. Thus, depending on the pre-treatment condition, we can change the redox properties of GdYVO₄:Eu³⁺ NPs in an opposite direction, which makes this nanomaterial a unique theranostic agent for radiation therapy (RT) enhancement, allowing the problem of radiation therapy (RT)-resistant hypoxic tumours to be overcome.

中文翻译：

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GdYVO4：Eu3 +纳米粒子在水溶液中X射线诱导的羟基自由基生成：主要机理

我们报道了强烈的X射线诱导的羟基自由基（^。 $\mathrm{Ø}\mathrm{H}$ ）生成的水溶液中包含紫外线预处理的GdYVO ₄：Eu ³⁺纳米粒子（L-GdYVO）。用光谱学方法进行检测^。 $\mathrm{Ø}\mathrm{H}$ 在解决方案中。机制的复杂性^。 $\mathrm{Ø}\mathrm{H}$ 世代已被揭示和讨论。获得的实验数据表明该机理的研究^。 $\mathrm{Ø}\mathrm{H}$ 生成与两个主要过程相关：（i）直接^。 $\mathrm{Ø}\mathrm{H}$ 通过在X射线照射下形成的热化h ⁺参与生成，以及（ii）在紫外线预处理下在纳米粒子（NPs）价带中形成的h ^+的X射线跃迁，并被局限在局部水平由随机散射电势形成。同时，对于在X射线辐照之前未暴露于紫外线的GdYVO ₄：Eu ³⁺纳米颗粒（D-GdYVO），归因于V ⁴⁺离子的电子给体性质的强辐射防护作用是观测到的。因此，根据预处理条件，我们可以更改GdYVO ₄：Eu ³⁺的氧化还原特性。 纳米粒子的方向相反，这使这种纳米材料成为增强放射治疗（RT）的独特治疗方法，从而克服了抗放射治疗（RT）的低氧肿瘤的问题。